DK201670317A1 - A method of and a system for determining a concentration of at least one preselected ion type and/or an element thereof - Google Patents

Abstract

The invention relates to a method of determining a concentration of at least one preselected ion type and/or an element of the preselected ion type in an aqueous sample fluid. In an embodiment the method comprises concentrating the preselected ion type of said aqueous sample fluid using 5 ion exchanger material and subjecting the concentrated preselected ion type to NMR measurements using an NMR spectroscope, collecting NMR data from the NMR measurements and correlating the collected NMR data to calibration data to determine the concentration of the preselected ion type and/or the element 10 of the preselected ion type in the aqueous sample fluid. The invention also relates to a The NMR system suitable for performing the method

Description

A METHOD OF AND A SYSTEM FOR DETERMINING A CONCENTRATION OF LEAST ONE PRESELECTED ION TYPE AND / OR AN ELEMENT THEREOF

TECHNICAL FIELD

The invention relates to a method and a system for determining a concentration of a component in an aqueous sample fluid. The method and system is particularly suitable for determining the concentration of one or more ions and / or one or more elements in an aqueous fluid, such as a lake water, waste water, process water and similar.

BACKGROUND ART

Concentrations of components in aqueous fluids such as waste water, drinking water, ground and surface water are determined today using different methods. For example, a standard method of determining common inorganic anions in environmental waters in the US is the use of ion chromatography.

Such methods generally require the use of large and expensive ion chromatographs and are generally very time consuming and labor consuming to perform.

Also laboratory analysis of the compounds in waste water by gas chromatography or mass spectrometry (GC / MS) is often applied to determine a concentration of selected components in an aqueous fluid.

Very often the component (s) that are / are relevant to the concentration determination is / are present in very small amounts which makes the concentration determinations very difficult, expensive and / or time consuming and often the determinations are rather inaccurate.

WO2015070874 discloses a method for determining at least one quality parameter, such as a concentration in an aqueous fluid using NMR spectroscopy. To increase the concentration of the relevant isotope to be measured by NMR the aqueous fluid is first subjected to a cross-flow filtration into a cross-flow filter, separating the aqueous fluid into a permeate fraction and a retentate fraction and thereafter performing NMR reading on the retentate fraction using an NMR spectroscope, collecting NMR data from the NMR reading and correlating the collected NMR data to calibration data to determine the at least one quality parameter of the aqueous fluid. For example, crossflow filtration may result in a 10 fold increase in concentration resulting in a factor of 100 reduced NMR reading time and / or a corresponding reduction in signal to noise level.

DISCLOSURE OF INVENTION

The object of the present invention is to provide an alternative method for determining a concentration of at least one preselected ion type and / or an element thereof in an aqueous sample fluid, which method is fast, reliable and very cost effective.

In an embodiment of the invention it is an object to provide a method for determining a concentration of at least one preselected ion type and / or an element thereof where the method can distinguish between preselected ion types and / or elements with a high accuracy and low noise.

In an embodiment of the invention it is an object to provide a system suitable for carrying out an alternative method for determining a concentration of at least one preselected ion type and / or an element thereof in an aqueous sample fluid, which method is fast, reliable and very cost effective and where the system can be applied to distinguish between preselected ion types and / or elements with a high accuracy and low noise.

These and other objects have been solved by the invention or embodiments thereof as defined in the claims and as described herein below.

It has been found that the invention or embodiments thereof have a number of additional advantages which will be apparent to the skilled person from the following description.

The method of the invention for determining a concentration of at least one preselected ion type and / or an element of the preselected ion type in an aqueous sample fluid comprises concentrating the preselected ion type of the aqueous sample fluid using ion exchanger material and subjecting the concentrated preselected ion type to NMR measurements using an NMR spectroscope. The method further comprises collecting NMR data from the NMR measurements and correlating the collected NMR data to calibration data to determine the concentration of the preselected ion type and / or the element of the preselected ion type in the aqueous sample fluid.

By concentrating the preselected ion type of the aqueous sample fluid using ion exchanger material prior to the NMR readings, the desired ion types can be concentrated while at the same time other non-desired ions or components are not concentrated. Such unwanted ions or components may be substantially removed or concentrated to a lesser degree. A completely new method of preparing the sample prior to NMR reading has been provided, where the ions in question may be separated into desired fractions thereby increasing the accuracy of the concentration determination and / or reducing the NMR reading time and / or allowing the use. of an NMR spectroscope with a lower magnetic field which reduces both the cost and the required space for the NMR spectrometer. In an embodiment the NMR system including the NMR spectrometer may be portable which is very beneficial e.g. for determining the concentration of an ion type and / or an element thereof at different positions of lakes, watercourses and / or rivers.

The term "ion type" means a specific ion or a group of ions having at least one element in common, such as a nitrogen containing ions or sulfur containing ions.

The term "element" means a chemical element.

The term "substantially" should herein be taken to mean that ordinary product variances and tolerances are comprised.

It should be emphasized that the term "comprising / comprising" when used herein is to be interpreted as an open term, i.e. it should be taken to specify the presence of specifically stated feature (s), such as element (s), unit (s), integer (s), step (s) component (s) and combination (s) thereof, but does do not preclude the presence or addition of one or more other stated features.

Throughout the description or claims, the singular encompasses the plural unless otherwise specified or required by the context.

Reference made to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment. Further, the skilled person will understand that particular features, structures, or characteristics may be combined in any suitable manner within the scope of the invention as defined by the claims.

Nuclear magnetic resonance - abbreviated NMR - is a phenomenon that occurs when the nuclei of an isotope in a magnetic field absorb and re-emit electromagnetic radiation. The emitted electromagnetic radiation has a specific resonance frequency which depends on the strength of the magnetic field and the magnetic properties of the isotope. NMR allows the observation of specific quantum mechanical magnetic properties of the atomic nucleus. Many scientific techniques exploit NMR phenomena to study molecular physics, crystals, and non-crystalline materials through NMR spectroscopy. NMR is also routinely used in advanced medical imaging techniques, such as magnetic resonance imaging (MRI). NMR measurement is performed by NMR spectroscopy and comprises using the NMR phenomenon to study materials e.g. for analyzing organic chemical structures. NMR spectroscopy is well known in the art and has for many years been applied to laboratory measurements in particular where other measurement methods could not be used. NMR spectroscopy is performed using an NMR spectrometer. Examples of spectrometer are e.g. described in US 6,310,480 and in US 5,023,551. A spectrometer comprises a unit for providing a magnetic field e.g. a permanent magnet assembly as well as a transmitter and a receiver for transmitting and / or receiving RF frequency pulses / signals. The RF receiver and RF transmitter are connected to an antenna or an array of RF antennae, which may be in the form of transceivers capable of both transmitting and receiving. The spectrometer further comprises at least one computing element, hereinafter referred to as a computer.

The intensity of nuclear magnetic resonance signals and hence the sensitivity of the technique depends on the strength of the magnetic field, and generally the NMR spectrometer applied for quantitative determination should have relatively large magnets - often electro or permanent magnets. The smaller the magnetic field, the more noise and accordingly the more measurements and time of NMR reading are required to obtain a desired accuracy.

General background of NMR formation evaluation can be found, for example in U.S. 5,023,551. A general background description of NMR measurement can be found in "NMR Logging Principles and Applications" by George R. Coates et al., Halliburton Energy Services, 1999. See in particular chapter 4.

Although 'NMR reading' in the following will often be used in singular to describe the invention, it should be noted that the singular term 'NMR reading' also includes a plurality of NMR readings unless otherwise specified. NMR reading means performing NMR spectroscopy on the sample in question.

The terms 'NMR reading' and 'NMR Measurement' are used interchangeably. The phrase "NMR accumulated reading time" means the total time for performing one or more NMR readings to obtain NMR data for at least one isotope to determine the concentration of at least one preselected ion type and / or element thereof from the aqueous fluid.

In an embodiment of the invention, the method comprises: • providing the ion exchanger material comprising exchange sites for the at least one preselected ion type; • passing a volume of VinflUent of the aqueous sample fluid through the ion exchanger material; and • subjecting the ion exchanger material to the NMR measurements and determining the concentration of the preselected ion type and / or the element of the preselected ion type in the aqueous sample fluid based on the collected NMR data and the volume VinflUent of the aqueous sample fluid .

In this embodiment, the NMR measurements are performed directly on the ion exchanger material with the captured ion type (s). Furthermore, a very accurate and specific determination of the concentration of the preselected ion type (s) and / or element (s) thereof may be achieved.

Advantageously the ion exchanger material is arranged at a reading zone of the NMR spectrometer prior to initiating the passage of the aqueous fluid through the NMR spectrometer, thereby monitoring the amount of captured ion types while pumping the volume of VinfiUent of the aqueous sample fluid through the ion exchanger material and it may be ensured that breakthrough is not reached.

The term "breakthrough" is herein used to mean the point at which the ion exchanger material cannot adsorb further ions of interest (i.e. those to be analyzed by NMR) and the ion exchanger material is exhausted.

The term "throughput" or "throughput volume" means the amount (volume) of aqueous fluid passed through the ion exchanger material prior to exhaustion of the ion exchanger material.

In the embodiment where the ion exchanger material is arranged in the reading zone of the NMR spectrometer, the ion exchanger material is advantageous of a material which has known and well defined NMR characteristics, such that the isotopes within the ion exchanger material do not affect the concentration determination. Thus, it is desired that the ion exchanger material does not comprise isotopes which are identical to or substantially indistinguishable from the isotopes measured on performing the concentration determination.

In a preferred embodiment the method comprises • providing the ion exchanger material comprising exchange sites for the at least one preselected ion type, • passing a volume of VinflUent of the aqueous sample fluid through the ion exchanger material; and • stripping off adsorbed ions from the ion exchanger material using a volume Veiution of an aqueous elution fluid, • performing the NMR measurements on the elution fluid, and • determining the ion concentration in the aqueous sample fluid based on the ratio of the volume of VinflUent of the aqueous sample fluid relative to the volume Veiution of the elution fluid.

The volume of the elution fluid is less than the volume of the aqueous sample fluid.

It has been found to be beneficial that the ion exchange process provides an enrichment rate of at least 2 of the preselected ion type (s) (ie a double concentration), such as an enrichment rate 3 to about 2000. Thus, in an embodiment the volume Veiution of the elution fluid is up to about 50% of the volume of VinfiUent of the aqueous sample fluid, such as up to about 25%, such as up to about 10%, such as from about 0.0005% to about 5%.

The preselected ion type (s) may in principle be any kind of ion type (s) comprising at least one NMR detectable isotope.

In an embodiment the at least one preselected ion type comprises at least one atom of an element selected from arsenic, antimony, boron, cadmium, chromium, cobalt, copper, lead, manganese, mercury, nickel, nitrogen, phosphorus, potassium, selenium, silver, thallium or zinc.

In an embodiment the at least one preselected ion type comprises at least one atom of an element selected from the transition metals or post transition metals.

In one embodiment, the method is used to determine the concentration of one or more heavy metals. This method is particularly advantageous for measuring waste water and or water from lakes, watercourses and / or rivers.

In an embodiment the at least one preselected ion type comprises a cation. Suitable examples of cations may comprise cations selected from metal cations, alkali metal cations alkaline earth metal cations and / or poly atomic cations.

In an embodiment the at least one preselected ion type comprises a cation selected from ammonium (NH4 +), aluminum (Al3 +), arsenic (As3 +), arsenic (As5 +), barium (Ba2 +), boron (B3 +), calcium (Ca2 +), cadmium (Cd2 +) chromium (III) (Cr3 +), chromium (IV) (Cr4 +), copper (I) (Cu +), copper (II) (Cu2 +), ion (II) (Fe2 +), ion (III) (Fe3 + ), lead (II) (Pb2 +), lead (IV) (Pb4 +), lithium (Li +), manganese (II) (Mg2 +), manganese (III) (Mn3 +), mercury (I) (Hg2 +), mercury (II ) (Hg2 + 2), silver (Ag +), sodium (Na +), strontium (Sr2 +), tin (II) (Sn2 +), tin (IV) (Sn4 +) and / or zinc (Zn2 +).

In an embodiment the at least one preselected ion type comprises an anion.

Suitable examples of anions may comprise anions selected from halogen ions, oxoanions, anions from organic acids, and / or polyatomic anions.

In an embodiment the at least one preselected ion comprises an anion selected from aluminum silicate (AISi032) azide (N3 ″), bicarbonate (HC03 ′), bromide (Br) (borate (B033 ′), carbonate (C032), bisulfate (HS04)) , bisulfite (HS03 '), chlorate (CI03'), chloride (CI-), chromate Cr042 '), cyanide (CN'), dichromate (Cr2072) dihydrogen phosphate (H2PO4 '), fluoride (F "), hydrogen phosphate ( HP042 '), Iodide (Γ), Metasilicate (Si032'), Nitrate (N03 '), Nitride (N3'), Nitrite (N02 '), Perchlorate (CI04'), Permanganate (Mn04 '), Phosphate (P043') , silicate (Si04 '4), sulfate (S042'), sulfide (S2 '), sulfite (S032'), selenite (Se032 ') and / or selenate (Se042').

In an embodiment the at least one preselected ion type comprises ions comprising the element N, such as two or more of ammonium (NH4 +), nitrate (N03 '), nitride (N3') and nitrite (N02 '). In this embodiment, the total concentration of the element N may be determined or the individual concentrations of the ions may be determined, e.g. using different ion exchanger material for the various ions and / or by eluting the ions by separate eluting fluid - e.g. separate eluting fluid having different pH value or ionic strength.

Several of the nitrogen ions are difficult to distinguish from each other by NMR measurement because the tops representing the 14N or 15N isotopes of nitrogen in the respective ions are relatively close to each other along the spectral band - i.e. delta PPM is relatively small, and distinguishing the various N containing ions from each other with high accuracy may require a relatively high magnetic field and / or a relatively long reading time. By separating the ions using ion exchanger material, the respective ions may be read separately thereby reducing the requirement for high magnetic field and long reading time.

The ion exchanger material may be of any type having capture sites for the preselected ion type (s), such as zeolites or resin with desired capture sites.

Advantageously ion exchange material is in the form of ion exchange resin, such as ion exchange resin comprising a support structure which is insoluble in the aqueous sample.

An ion exchange resin is typically a polymeric material, such as polystyrene with electrically charged sites forming capture (exchange sites) sites for the preselected ion (s).

Synthetic ion exchange resins are usually cast as porous beads with considerable external and pore surface where ions can attach. The resin is advantageously crosslinked to a desired degree to ensure high mechanical strength of the bead while simultaneously ensuring a high capacity and a fast ion exchange (also referred to as the time required to reach equilibrium conditions).

The total capacity of an ion exchange resin is defined as the total number of chemical equivalents available for exchange per unit weight or unit volume of resin.

The more highly crosslinked a resin, the more difficult it becomes to introduce additional functional groups. Thus, a too highly crosslinked resin may have a relatively low capacity.

Further the desired crosslinking degree may also depend on the size of the preselected ion type (s) because a high crosslinking may reduce the diffusion time for relatively large ions.

The physical size of the resin beads is advantageously selected to provide a desired high flow while simultaneously ensuring that substantially all of the preselected ion type (s) are captured by the ion exchanger material. Suitable sizes of ion exchange resin beads include sizes of about 0.01 - 2 mm in average diameter measured using laser diffraction.

Advantageously, the ion exchanger material comprises support structure such as polystyrene having functional groups bonded thereto. The functional groups are selected to form ion exchange sites for the at least one preselected ion type. In an embodiment, the functional groups may form cationic capture sites, and may include, for example, carboxylic acid groups or sulfonic acid groups, such as sodium polystyrene sulfonate or poly (acrylamido-N-propyltrimethylammonium chloride). In an embodiment the functional groups may form anionic sites, and may for example include secondary, ternary and / or quaternary amino groups such as polyethylene amine or trimethylammonium groups.

An embodiment of the ion exchanger material is a chelating resin, preferably comprising functional groups selected from iminodiacetic acid, aminophosphonic, thiourea and / or 2-picolylamine. An example of a chelating resin is Amberlite IRA743 which is a macroporous styrenic resin with methyl glucamine functionality. The active group is essentially a weak base (tertiary amine) with a "sugar tail"

Chelating resins are particularly suitable for capturing ions comprising lead, copper, zinc, aluminum, cadmium, nickel, cobalt, magnesium, barium, boron, strontium, iron and / or mercury. Suitable chelating resins include the resin marketed by Polysciences, Inc., marketed under the tradename "Purolite ®".

In an embodiment the ion exchange resin is in the form of a membrane and / or in the form of a bed of beads.

The amount of ion exchanger material is selected in dependence on the expected concentration and the preselected ion type (s) such that a desired concentration for NMR measurement can be obtained.

The amount of ion exchanger material is, for example, from about 0.0001 to about 0.1 L per L VinflUent of the aqueous sample fluid, such as from about 0.0005 to about 0.01 L per L VinflUent of the aqueous sample fluid.

The ion exchanger material may comprise a cation exchanger material, an anion exchanger material or any combination or mixtures thereof.

Where several types of anion exchanger material or several types of cation exchanger material are used these several types may be mixed or kept separately. In an embodiment the ion exchanger material comprises a mixture of several types of anion exchanger material or a mixture of several types of cation exchanger material. The several types of ion exchange material may have capture sites for different ions, which may be eluted in separate elution fluids for separate concentration determinations.

In an embodiment the ion exchanger material comprises two or more ion exchanging sub units arranged in parallel or in series. The two or more ion exchanger sub units may be equal or different from each other with respect to size, shape and / or ion exchanger material. The method can be used in a variety of different ways to determine the desired concentration (s)

In an embodiment the ion exchanger material comprises two or more ion exchanger sub units arranged in series, the two or more ion exchanger sub units comprising at least one anion exchanger sub unit and at least one and at least one cation exchanger sub unit. Thereby cation and anion may be captured by respective ion exchange resin and be eluted separately from each other.

In an embodiment the ion exchanger material comprises the two or more ion exchanger sub units arranged in parallel, the two or more ion exchanger sub units comprising at least one anion exchanger sub unit and at least one cation exchanger sub unit.

In an embodiment the ion exchanger material comprises the two or more ion exchanger sub units arranged in parallel, while the two or more ion exchanger sub units comprise mixed anion exchanger material and cation exchanger material. In this embodiment, it may be desired to arrange the ion exchanger material in an electrodeionization for electrically assisted elution of captured ions.

The electrodeionization for electrically assisted elution of captured ions may e.g. be performed according to the methods described in US 2015/0225267, US 2010/0096269, US 2006/0266651 and / or EP 2 112 125.

Advantageously the volume of the aqueous sample fluid is selected to be less than a calculated or determined volume of the aqueous fluid for reaching breakthrough - i.e. less than the throughput volume. Preferably, to maintain a security margin, the volume of the aqueous sample fluid is selected to be less than about 80% or less of the calculated volume to ensure that breakthrough of the preselected ion type is not reached. To ensure effective concretion, the aqueous sample fluid is advantageously selected to be at least about 30% of the calculated volume to ensure that breakthrough of the preselected ion type is not reached.

For example, the calculated volume of the aqueous fluid for reaching breakthrough volume of the aqueous sample fluid may be obtained by estimating a concentration of the preselected ion type and calculating the volume of the fluid required for reaching breakthrough of the preselected ion type based on the estimated concentration of the preselected ion type.

For example, the determined volume of the aqueous fluid for reaching breakthrough may be obtained by NMR measurement, preferably the breakthrough is determined by performing NMR measurement on the aqueous sample fluid after passing the ion exchanger material (the effluent), determining when an NMR signal caused the preselected ion type is detected and determines the volume of the aqueous fluid for reaching breakthrough as the volume that has passed the ion exchanger material until the breakthrough.

Advantageously, the volume of VinflUent of the aqueous sample fluid is selected relative to the type and amount of ion exchanger material, preferably such that at least about 10% of an exchange capacity of the ion exchanger material is used. Generally it is desired to use as much as possible of the exchange capacity of the ion exchanger material, while still holding a security margin to breakthrough. In an embodiment at least about 40% of the exchange capacity of the ion exchanger material is used, more preferably such that from about 50% to about 80% of the exchange capacity of the ion exchanger material is used.

For example, the volume of the aqueous sample fluid is from about O.lvL to about 1000 L, such as from about 10 to about 500 L, such as from about 25 L to about 300 L.

The amount of elution fluid is less than the amount of aqueous sample fluid as described above.

The amount of elution fluid is advantageously kept as low as possible while simultaneously ensuring a substantially full elution of the captured ions on the ion exchanger material.

For a given ion exchanger material and a given preselected ion type, the optimal amount of elution fluid may be determined.

In an embodiment the ion exchanger material comprises an anionic ion exchanger material having a pKa value and the elution fluid having a pKa higher than the pKa value of the anionic ion exchanger material, preferably the elution fluid is an aqueous solution of caustic soda (NaOH). , caustic potash (potassium hydroxide KOH), Ammonia (NH3), Sodium carbonate (soda ash, Na2CO3) and / or lime (calcium hydroxide, Ca (OH) 2). The elution fluid passed through the ion exchanger material may gradually or stepwise increase in pKa value such that different ions or amounts thereof are eluted at different pKa values.

In an embodiment the ion exchanger material comprises a cationic ion exchanger material having a pKa value and the elution fluid having a pKa lower than the pKa value of the cationic ion exchanger material, preferably the elution fluid is an aqueous solution of hydrochloric acid (HCI). , Sulfuric acid (H2S04) nitric acid (HN03) acetic acid (CH3COOH) and / or citric acid (C6H807). The elution fluid passed through the ion exchanger material may gradually or stepwise decrease in pKa value such that different ions or amounts thereof are eluted at different pKa values.

The elution may be performed in co-flow or in counter flow through the ion exchanger material.

To ensure full elution the elution fluid may be recirculated through the ion exchanger material preferably for two or more times and / or for a predetermined time, such as for 1 minute or more, such as for 10 minutes or more, such as up to one hour.

To ensure full elution the ion exchanger material may be subjected to stirring at least for a selected time while in contact with the elution fluid. The stirring may be performed by rotating or shaking the container comprising the ion exchanger material. In addition, it may be ensured that the elution fully wets the ion exchanger material and does not find shortcuts through the ion exchanger material.

Advantageously, the elution fluid is passed directly from the ion exchanger material and into the NMR spectroscope to perform the NMR measurement (s), preferably on the elution fluid in flow state through the NMR measurement zone. Thereby the NMR system can be provided as a very compact system. A flow sensor is advantageously arranged for determining the elution fluid through the NMR measurement zone.

The elution fluid may have an elution profile which is not constant and the NMR system is advantageously configured to determine the elution profile to determine the total amount or average amount of the preselected ion type (s) in the elution fluid.

In an embodiment, the elution fluid or portions thereof are temporarily collected in an intermediate space prior to being passed to the NMR spectroscope to perform the NMR measurement (s). Thereby the elution fluid or portions thereof may be intermixed to achieve substantial homogeneity with respect to the preselected ion type (s).

The intermediate space may preferably be a space within a piston pump for pumping the elution fluid to the NMR spectroscope. Thus when the piston pump is operating the elution fluid is intermixed by the induced turbulence.

In an embodiment the ion exchanger material consists essentially of anion ion exchanger material and the volume Veiution of elution fluid is elution fluid for stripping off adsorbed anions from the anion exchanger material.

In an embodiment the ion exchanger material consists essentially of cation exchanger material and the volume Veiution of elution fluid is elution fluid for stripping off adsorbed cation from the cation exchanger material.

In an embodiment the ion exchanger material comprises both anion exchanger material and cation exchanger material, preferably in the form of two or more ion exchanger sub units, and the volume Veiution of elution fluid is elution fluid for stripping off adsorbed cation from the cation exchanger material or the volume Veiution of elution is elution fluid for stripping off adsorbed anions from the anion exchanger material.

In an embodiment where the ion exchanger material comprises both anion exchanger material and cation exchanger material and the method comprises • passing the volume of VinflUent of the aqueous sample fluid through the ion exchanger material comprising the anion exchanger material and the cation exchanging resign • stripping off adsorbed anions and cations using electrodeionization from the anion and cation exchanger material using a volume Veiution of an aqueous anion + cation elution fluid, • performing the NMR measurements on at least one of the anion elution and the cation elution fluid using the NMR spectroscope, volume Veiution of the anion + cation elution fluid is less than the volume of Vinfiuent of the aqueous sample fluid.

The NMR measurements may comprise reading at least one NMR readable isotope comprised in the at least one preselected ion. In an embodiment of the NMR measurements, companies read a plurality of NMR readable isotopes.

The NMR measurements may comprise NMR reading of one or more of the isotopes 4Η, 10B, UB, 13C, 14N, 15N, 160, 19F 23Na, 27AI, 29Si 31P, 33S, 35CI, 37CI, and 39K, 41K, 43Ca, 47Ti , 49Ti, 50V, 51V, 53Cr, 55Mn, 57Fe, 59Co, 61Ni, 63Cu, 65Cu, 67Zn, 69Ga, 71Ga, 75As, 77Se, 79Br, 81Br, 83Kr, 85Rb, 87Rb, 87Sr, 89Y, 91Zr, 93Nb, 95Mo , 97Mo, 105Pd, 107Ag, 109Ag, luCd, 113Cd, 117Sn, 119Sn, 115Sn, 121Sb, 135Ba, 137Ba 177Pb, 199Hg, 201Hg, 207Pb, preferably the method comprises a plurality of readings of one or more of 13C, 14N, 19F 23Na, 31P, 35CI, 37CI, 39K, 79Br, and 81Br.

Advantageously, the NMR measurements comprise NMR reading of one or more heavy metal isotopes, such as isotopes of Pb, Fig and / or Cd.

In an embodiment of the NMR measurements, a plurality of consecutive NMR readings comprise one or more NMR readable isotopes preferably comprising at least one of 13C, 14N, 19F, 23Na, 31P, 35CI, 39K, 79Br, and 81Br.

In an embodiment the NMR measurements comprise NMR reading of 35CI and / or 37CI and the method comprises determining the concentration of one or more Cl containing ions in the aqueous sample fluid.

The concentration of the at least one preselected ion type in the aqueous sample fluid may be determined by generating NMR data from the NMR measurements and correlating the NMR data to calibration data and determining the concentration of the preselected ion type (s) and / or the element (s) thereof in the aqueous sample fluid, preferably at least one preselected ion type in the aqueous sample fluid is determined by generating NMR data from the NMR measurements and correlating the NMR data calibration data and determining the concentration of the preselected ion type (s) in the used elution fluid and determining the concentration of the preselected ion type (s) in the aqueous sample fluid by adjusting for the ratio of the volume VinflUent relative to the volume Veiution ·

The method may in an embodiment comprise determining the concentration of at least one element of the at least one ion, the at least one element being preferably selected from arsenic, antimony, boron, cadmium, chromium, cobalt, copper, lead, manganese, mercury , nickel, nitrogen, phosphorus, potassium, selenium, silver, thallium or zinc.

The method may comprise performing control readings.

In an embodiment the method comprises performing NMR readings on unfiltered (not passed through the ion exchanger material) fluid sample of the aqueous fluid at predetermined interval. To obtain an accurate result, the reading time of the unfiltered aqueous fluid is advantageously longer than the reading time of filtered aqueous fluid. By comparing the resulting determined concentration it can be verified whether the method is operating as desired.

The NMR measurements may comprise simultaneously subjecting the elution fluid to a magnetic field B, and a plurality of pulses of radio frequency energy E (RF pulses) and receiving relaxation signals from excited nuclei, preferably the relaxation signals comprise a free induction decay (FID). spectrum. TFIE NMR reading may e.g. be performed as described in WO 2015/148529.

For example, the NMR measurements may comprise subjecting the elution fluid to proton decoupling pulses and / or polarization pulses during at least part of the NMR reading.

The NMR measurements may comprise enhancing signal to noise of the data spectra by subjecting the elution fluid to a pulse configuration providing polarization and / or proton decoupling of atoms of one or more compounds in the sample.

The NMR measurements may comprise enhancing signal to noise of the data spectra by subjecting the elution fluid to a pulse configuration comprising at least one of DEPT (Distortionless Enhancement by Polarization Transfer), DEPTQ (DEPT with retention of Quaternaries), HSQC (Heteronuclear Single

Quantum Coherence), INEPT (Insensitive Nuclei Enhanced by Polarization Transfer), BIRD (Bilinear Rotation Decoupling Pulses), TANGO (Testing for Adjacent Nuclei with a Gyration Operator) or NOE (Nuclear Overhauser Effect).

The NMR measurements may be performed in a magnetic field of up to about 25 Tesla, such as from about 0.3 Tesla to about 15 Tesla, such as from 0.3 to about 2.5 Tesla, such as up to about 1.5 Tesla. It has been found that where the aqueous sample flow is concentrated and optionally fractionated by ion exchanging the method of the invention ensures that a very accurate and reliable concentrate determination which may additionally be obtained relatively fast even when using a relatively low magnetic field, e.g. 2.5 Tesla or less or even 1.5 Tesla or less. Thereby the method is very economically advantageous.

The method may in principle be used on any type of aqueous fluid, such as drinking water; waste water, such as industrial waste water, hospital waste water or municipal waste water; lake water; swimming pool water or aquaculture water.

The invention also relates to an NMR system suitable for determining a concentration of at least one preselected ion type and / or an element thereof in an aqueous sample fluid.

The NMR system comprises an amount of ion exchanger material, an NMR spectrometer, a digital memory storage, a calibration map comprising calibrating data for calibrating NMR data obtained by the NMR spectrometer and a computer programmed to analyze the NMR data obtained by the NMR spectrometer using the calibration map and performing a determination of the concentration of the at least one preselected ion.

Advantageously the NMR system comprises an ion exchange apparatus comprising ion exchanger material. The ion exchange apparatus advantageously comprises the ion exchanger material in a suitable container, such as a cartridge for performing the ion exchange. The ion exchanger material may e.g. be arranged in the container as an ion exchange bed for co-flow or counter-flow. In an embodiment the ion exchange apparatus comprises an electrodeionization module. The ion exchange apparatus is advantageously coupled to the NMR spectrometer, such that the ion exchanger material is arranged in a reading zone of the NMR spectrometer or the ion exchange apparatus is coupled to the NMR spectrometer to provide a liquid flow path from the ion exchanger material to a reading zone of the NMR spectrometer, preferably in a direct in-line configuration.

In an embodiment of the ion exchange apparatus, a co-flow apparatus is the aqueous sample fluid and the elution fluid passing the ion exchanger material with the same flow direction.

In an embodiment of the ion exchange apparatus, a counter-flow apparatus is the aqueous sample fluid and the elution fluid passing the ion exchanger material with opposite flow direction.

In an embodiment of the ion exchange apparatus is an electrodeionization apparatus and the ion exchanger material is a mixture of anion resin and cation resin, the electrodeionization apparatus preferably comprises a stack of adjacent and alternatively arranged ion exchanger material chambers and elution fluid chambers, separated by alternately arranged cation exchange membranes and anion exchange membranes and a set of DC electrodes located on either sides of the stack of chambers.

The NMR system is advantageously configured to perform the method described above. In an embodiment the computer is programmed to control the NMR spectrometer, the ion exchange apparatus and at least one pump for performing one or more of the methods described above.

The NMR system advantageously comprises a flow analyzer. The flow analyzer may be adapted to determine at least one of the amount of the aqueous sample fluid flowing through the ion exchanger material, the amount of the elution fluid flowing through the ion exchanger material, the velocity of the aqueous sample fluid flowing through the ion exchanger material, the velocity of the aqueous sample fluid flowing through the ion exchanger material.

All features of the inventions and embodiments of the invention as described herein including ranges and preferred ranges may be combined in various ways within the scope of the invention, unless there are specific reasons not to combine such features.

Brief description of the drawings

The above and / or additional objects, features and advantages of the present invention will be further elucidated by the following illustrative and nonlimiting description of embodiments of the present invention, with reference to the appended drawings.

FIG. 1 is a table of different concentrations which may be obtained by embodiments of the method of the invention.

FIG. 2 is a table showing maximum admissible amount of heavy metals in drinking water.

FIG. 3 is a table showing standards for certain waste waters.

FIG. 4 is a schematic illustration of a first embodiment of the NMR system of the invention.

FIG. 5 is a schematic illustration of a second embodiment of the NMR system of the invention.

FIG. 6 is a schematic illustration of a third embodiment of the NMR system of the invention.

FIG. 7 is a schematic illustration of a fourth embodiment of the NMR system of the invention.

FIG. 8 is a schematic illustration of a fifth embodiment of the NMR system of the invention.

FIG. 9 is a schematic illustration of a sixth embodiment of the NMR system of the invention.

FIG. 10 is a schematic illustration of a seventh embodiment of the NMR system of the invention.

FIG. 11 is a schematic illustration of an eight embodiment of the NMR system of the invention.

Figs. 12, 13, 14 and 15 show different elution profiles.

The figures are schematic and may be simplified for clarity. Throughout the same reference numerals are used for identical or corresponding parts.

Further scope of applicability of the present invention will become apparent from the description given hereinafter. Flowever, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are provided by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art. the art from this detailed description.

The table of FIG. 1 is a list of examples of target elements and target ion types for which the concentration in an aqueous sample fluid e.g. as listed in the table may be determined. The table illustrates which ions the exchanger material may have capture sites for and which isotopes may be read by the NMR spectrometer. For example, to determine the concentration of Al element in a waste water aqueous fluid, the ion exchanger material may have capture sites for Al3 + and optionally for AIS1O32 '- i.e the ion exchanger material may comprise both an anionic resin and a cationic resin.

The table of FIG. 1 provides a number of examples, but it should be understood that the table in non exhaustive and many other concentrations may be determined according to the invention as defined in the claims and / or as described herein.

FIG. 2 lists the maximum admissible amount of heavy metals in drinking water for a number of national and international organizations.

Heavy metals are natural components of the Earth's crust. To a small extent they enter our bodies via food, drinking water and air. As trace elements, some heavy metals (e.g. copper, selenium, zinc) are essential to maintain the metabolism of the human body. However, at higher concentrations they can lead to poisoning. Heavy metal poisoning could, for instance, result from drinking-water contamination (e.g. lead pipes) and water supply by industrial and consumer waste, or even from acidic rain breaking down soils and releasing heavy metals into streams, lakes, rivers, and groundwater.

Heavy metals tend to bioaccumulate which makes it even more important to ensure that the maximum admissible amount of heavy metals in drinking water is not exceeded, and thus it is also important to monitor the concentration of heavy metals in drinking water. The method of the present invention is highly suitable and very effective for determining the concentration of heavy metal in drinking water. An embodiment of the NMR system may advantageously be permanently or temporarily installed in a drinking water reservoir for monitoring the concentration of one or more heavy metals in the drinking water. As seen in the table of Fig. 2, the maximum admissible amount of the respective heavy meals is very low which means that very small amounts need to be determined in a fast and reliable way. This task is solved by the method and system described herein.

The contaminants found in wastewater are varied and numerous and may include, for example, organic material, pathogens, metals, salt, ammonia, pesticides, pharmaceuticals, and endocrine disrupters. Many of the contaminants, such as heavy metals, are harmful to both humans and the environment. Others, such as nitrates and phosphorus, may be deleterious if the effluent is being discharged to receive waters but may be advantageous in certain concentrations if the effluent is going to be reused for agricultural irrigation. Therefore, it is important to know and preferably monitor the concentration of various contaminants in the wastewater before it is discharged to the environment.

The table of FIG. 3 shows maximum levels of total dissolved solids (TDS) and heavy metal salts in wastewater.

Total dissolved solids comprise inorganic salts (principally calcium, magnesium, potassium, sodium, bicarbonates, chlorides and sulfates) found in wastewater. Effluents with high levels of TDS are not suitable for irrigation or landscaping because many plants are intolerant of the chlorides and the TDSs may leach into the groundwater. Effects with high levels of TDS are also not desirable for industry giants because they will cause corrosion and incrustation.

The method of the present invention is highly suitable and very effective for determining one or more contaminants in wastewater. An embodiment of the NMR system may advantageously be permanently or temporarily installed to monitor the concentration of one or more contaminants in the wastewater optionally in connection with a waste water cleaning plant.

The first embodiment of the NMR system of the invention shown in FIG. 4 comprises an inflow pipe 1 leading to a valve A comprising at least three settings, a first setting where fluid from the inflow pipe 1 is passed directly via a pipe 2a to an NMR spectrometer 4 from where the fluid may be passed further via pipe 2b to a not shown waste reservoir, a second setting where the fluid from the inflow pipe is passed further to an ion exchanger material in an ion exchange module 5 and a third setting for elution where elution fluid may pass from the ion exchange module 5 to the NMR spectrometer 4.

On the opposite side of the ion exchange module 5, the module 5 is in fluid connection with a valve B which has at least two settings, a first setting where fluid which has passed through the ion exchanger material of the ion exchange module is passed to a sample outflow pipe 6 eg for being discharged or for being sent to a cleaning plant, and a second setting where an elution fluid is passed from a not shown elution reservoir and via elution fluid inflow pipe 7 to the ion exchange module 5 in backflow though the ion exchanger material.

The NMR system comprises at least one pump not shown. The pump or pumps may be positioned anywhere suitable for pumping the fluid (s).

In one embodiment, one pump is used to pump both the aqueous sample fluid directly to the NMR spectrometer and the elution fluid, such pump may, for example, be positioned on pipe 2b between the NMR spectrometer 4 and the waste reservoir not shown. An additional pump may be applied for pumping the aqueous sample fluid through the ion exchange module.

In one embodiment the NMR system comprises one pump for pumping the aqueous sample fluid - e.g. positioned at the aqueous sample fluid inflow pipe 1, and one pump for pumping the elution fluid - e.g. positioned at the elution fluid inflow pipe 7.

The NMR system advantageously further comprises at least one flow analyzer as described above.

In use the valve A is in its second setting and valve B is in its first setting. A volume of solvent of the aqueous sample fluid is pumped via the inflow pipe 1 through the ion exchanger material in the ion exchange module 5 and out through the aqueous sample fluid outflow pipe 6.

Thereafter valve A is switched to its third setting and valve B is switched to its second setting. A volume of an aqueous elution fluid is now pumped via the elution fluid inflow pipe 7 and backflow through the ion exchanger material in the ion exchange module 5 and into the NMR spectrometer 4 for being measured in a NMR measurement zone not shown. NMR spectrometer 4. Thereafter the elution fluid may be discharged via pipe 2b.

The measuring circle may be repeated if desired.

At desired intervals, valve A may be switched to its first setting and unfiltered portion of aqueous fluid may be pumped directly to NMR spectrometer 4 for NMR measurements. This may advantageously be performed immediately before the volume of VinfiUent of the aqueous sample fluid is pumped via the inflow pipe 1 through the ion exchanger material in the ion exchange module 5, whereby the NMR spectrometer may read on the unfiltered aqueous fluid while the volume of VinflUent of the aqueous sample fluid is pumped through the inflow pipe 1 and through the ion exchanger material into the ion exchange module.

The second embodiment of the NMR system of the invention shown in FIG. 5 comprises an aqueous sample fluid inflow pipe 11 for inflow of an aqueous sample fluid and an elution fluid inflow pipe 17 for inflow of an elution fluid, both inflow pipes 11, 17 leading to a valve A, comprising at least two settings, a first setting where fluid from the aqueous sample fluid inflow pipe 11 is passed via pipe 15a to an ion exchanger material in an ion exchange module 15 and a second setting where elution fluid is passed from the elution fluid inflow pipe 17 and via pipe 15a to the ion exchange module 15 for elution of captured ions.

From the ion exchange module 15 the fluid may be passed through the ion exchange module outflow pipe 15b to a valve B which has two settings including a first setting where the fluid is passed from the ion exchange module outflow pipe 15b via pipe 12a to an NMR spectrometer 14. A piston pump 18 is in fluid connection via pipe 12c with the NMR spectrometer 14 for pumping the fluid. The piston pump 18 preferably has a narrow orifice inlet to assist fluid mixing inside the piston pump space. A second setting of valve B provides a flow path backwards from NMR spectrometer 14 via pipes 12a and 12b to a reservoir not shown, such as a waste reservoir, a giant reservoir or a discharge reservoir.

The NMR system advantageously further comprises at least one flow analyzer as described above. A typical use sequence is as follows:

The valve A is set in its first setting and valve B is set in its first setting. A volume of the aqueous sample fluid is pumped via the inflow pipe 11 and pipe 15a through the ion exchanger material into the ion exchange module 15 and out of the ion exchange module 15 and through pipes 15b, 12a and 12c to the space in the piston pump 18. Not all of the filtered fluid needs to be collected in the space of piston pump 18, some of the aqueous sample fluid may remain in pipes 12a and 12c or in the NMR spectrometer.

In a variation thereof, the aqueous sample fluid is recirculated e.g. up to 10 times through the ion exchange module 15 via a not shown bypass pipe leading from the pipe ion exchange module outflow pipe 15b prior to being collected temporarily in the piston pump 18 and to the inflow pipe 15a.

After the volume of the aqueous sample fluid has passed through the ion exchange module 15 one or more times, the valve B is switched to its second position and the piston pump it switched to backward pumping for emptying the pump 18, the NMR spectrometer 15 and the pipes 12a, 12c to the reservoir via pipe 12b.

Thereafter valve A is switched to its second setting and valve B is switched back to its first setting. A volume Veiution of an aqueous elution fluid is now pumped via the elution fluid inflow pipe 17 and pipe 15a through the ion exchanger material in the ion exchange module 15 for eluting the captured ions and further out of the ion exchange module 15 and via pipes 15b , 12a and 12c to the space in the piston pump 18. Not all of the elution fluid needs to be collected in the space of the piston pump 18, some of the aqueous sample fluid may remain in the pipes 12a and 12c or in the NMR spectrometer. However, in a preferred embodiment substantially all of the elution fluid or substantially all of the elution fluid containing eluted ions is collected in the piston pump space. Since the piston pump space is well defined this defined volume of space may be used to determine the volume of the elution fluid. The NMR spectrometer 14 may be switched on during the elution phase to determine an elution profile and to ensure that substantially all of the collected ions are eluted. Preferably, the NMR spectrometer 14 is switched on at least for measuring the elution fluid containing the elution peak of the preselected ion types.

In the space of the piston pipe 18 the elution fluid is intermixed to be substantially homogeneous with respect to ion concentration.

If desired also the elution fluid may be recirculated through the ion exchange module 15 in the same way as the aqueous sample fluid.

After the volume Veiution of the aqueous elution fluid has passed through the ion exchange module 15 one or more times, the valve B is switched to its second position and the piston pump it switched to backward pumping for emptying the pump 18 to the reservoir via the NMR spectrometer 14 while at the same time the NMR spectrometer 14 is switched on to perform NMR measurement on the elution fluid comprising the preselected ion type (s).

The NMR spectrometer is connected to a not shown computer comprising a calibration map and programmed to calculate the concentration of the at least one preselected ion type and / or element thereof in the aqueous sample fluid. The computer is advantageously also programmed to operate the NMR system for carrying out the described method.

The third embodiment of the NMR system of the invention shown in FIG. 6 comprises an aqueous sample fluid inflow pipe 21 leading to a valve D with two settings, where the first setting via secondary inflow pipe 21b leads to a valve A. An elution fluid inflow pipe 27 for inflow of an elution fluid also leads to the valve A. The valve A comprises at least two settings, a first setting where fluid from the aqueous sample fluid inflow pipe 21a, 21b is passed via pipe 25a to an ion exchanger material in an ion exchange module 25 and a second setting where elution fluid is passed from the elution fluid inflow pipe 27 and via pipe 25a to the ion exchange module 25 for elution of captured ions.

From the ion exchange module 25 the fluid may be passed through the ion exchange module outflow pipe 25b to a valve B which has two settings including a first setting where the fluid is passed from the ion exchange module outflow pipe 25b via pipe 22a, 22a 'to An NMR spectrometer 24. A piston pump 28 is in fluid connection via pipe 22c with the NMR spectrometer 24 for pumping the fluid.

The piston pump 28 preferably has a space within a nozzle for temporarily collection of fluid. A second setting of valve B provides a flow path backwards from NMR spectrometer 24 via pipes 22a, 22a 'and 22b to a reservoir not shown.

The valve D has a second setting where the aqueous fluid is passed through a third inflow pipe section 21c to a valve C positioned at the pipe sections 22a, 22a 'between valve B and the NMR spectrometer 24. The valve C has a first setting where fluid can pass from the ion exchange module 25 to the NMR spectrometer 24 and a second setting where aqueous fluid can pass from the inflow sections 21a, 21c and directly to the NMR spectrometer 24.

The NMR spectrometer comprises a bypass circuit 29 such that fluid may be circulated through a measuring zone of the NMR spectrometer 24. The NMR spectrometer 24 further comprises pinch valves at the entry and exit from the measuring zone of the NMR spectrometer. The NMR spectrometer may advantageously be described in co-pending application DK PA 2015 70758. A typical use sequence is as follows:

The valve C is set in its second position and the valve D is set in its second position. Aqueous fluid is pumped directly to the NMR spectrometer for NMR reading on unfiltered sample. The unfiltered sample may be NMR measured in flow or in locked (non-flowing) mode. The ion concentration is low, but longer analysis gives better signal / noise relation and the reading of the unfiltered sample may continue while the aqueous sample fluid is loaded through the ion exchanger material.

While continuing NMR reading on the unfiltered sample, valve D is switched to its first setting, valve C is switched to its first setting, valve A is set to its first setting, and valve B is set to its first setting. A volume of liquid aqueous sample fluid is pumped via the inflow pipe 21a, 21b and pipe 25a through the ion exchanger material into the ion exchange module 25 and out of the ion exchange module 25 and via the ion exchange module outflow pipe 25b and pipes 22a , 22a 'and 22c to the space in the piston pump 28. As before not all of the filtered fluid needs to be collected in the space of the piston pump 28. After the volume VinfiUent of the aqueous sample fluid (or a part thereof correspondingly) to the pump volume) passed through the ion exchange module 25, the valve B is switched to its second position and the piston pump it switched to backward pumping for emptying the pump 28 bypassing the NMR spectrometer 24 via bypass 29 through the pipes 22a ' , 22a, valve B and 22b to the reservoir. Where the volume of VinfiUent of the aqueous sample fluid is larger than the pump volume, the procedure may be repeated until all of the volume VinflUent of the aqueous sample fluid has passed through the ion exchange module 25. The unfiltered sample may be kept inside the NMR for continuous analysis as long as desired eg until all of the volume VinflUent of the aqueous sample fluid has passed through the ion exchange module 25. Then the unfiltered sample in the NMR spectrometer 24 is emptied out to the reservoir. The NMR spectrometer 24 is now empty and therefore switched off.

Thereafter valve A is switched to its second setting and valve B is switched back to its first setting. A volume of aqueous elution fluid is now pumped via the elution fluid inflow pipe 27 and pipe 25a through the ion exchanger material in the ion exchange module 25 to elute the captured ions and further read by the NMR spectrometer 24 in the same way as described in the second embodiment.

The NMR spectrometer is connected to a not shown computer comprising a calibration map and programmed to calculate the concentration of the at least one preselected ion type and / or element thereof in the aqueous sample fluid. The computer is advantageously also programmed to operate the NMR system for carrying out the described method.

The third embodiment allows the locking and analysis of part of the original unfiltered sample with low ion concentration in NMR tube while enriching more of the same sample in the ion exchange module.

The fourth embodiment of the NMR system of the invention shown in FIG. 7 comprises an aqueous sample fluid inflow pipe 31 for inflow of an aqueous sample fluid and an elution fluid inflow pipe 37 for inflow of an elution fluid, both inflow pipes 31, 37 leading to a valve A, comprising at least two settings. In the first setting of the valve A fluid from the aqueous sample fluid inflow pipe 31 is passed to an ion exchanger material in an ion exchange module 35 via a pump 38, while passing a flow analyzer 39 and further from the ion exchange module 35 to and NMR spectrometer 34 and further to waste.

In the second setting of the valve A fluid from the elution fluid inflow pipe 37 is passed to the ion exchanger material in an ion exchange module 35 via a pump 38, while passing a flow analyzer 39 and further from the ion exchange module 35 to the NMR spectrometer 34 and further to waste.

In use the valve A is in its first setting. The pump is started and a volume of VinAuent of the aqueous sample fluid is pumped through the ion exchanger material in the ion exchange module 35 and into the waste.

Thereafter the valve is switched to its second setting and elution fluid is passed through the ion exchange module 35 to elute the captured ions.

From the ion exchange module 34 the elution fluid is pumped to the NMR spectrometer 34 for being analyzed by NMR measurements. The flow analyzer 39 determines the flow of the respective fluids and thereby the amounts (volume) of the respective fluids can be determined.

In a variation of the elution fluid is sent in counter flow through the NMR spectrometer 34.

The pump may be any kind of liquid pump, such as a peristaltic pump, a diaphragm pump or a piston and / or metering pump.

The fifth embodiment of the NMR system of the invention shown in FIG. 8 is a variation of the fourth embodiment. The NMR system of the fifth embodiment differs from the NMR system of the fourth embodiment in that the ion exchange module 45 comprises a bypass pipe 45a for recirculating the aqueous sample fluid and / or the elution fluid through the ion exchanger material of the ion exchange module 45 to increase the capturing and / or releasing of ions or for bypassing aqueous fluid to be sent directly to NMR spectrometer 54. Further, NMR spectrometer 44 also includes a bypass pipe 44a for recirculating the fluid in NMR spectrometer 45 or for bypassing aqueous sample fluid that has passed through the ion exchange module 45. In use the NMR system may operate as described for the further embodiment.

Flowever, the fifth embodiment also operates in a second mode allowing original unfiltered sample with low analyte concentration to be locked in the NMR tube for NMR analysis while the aqueous sample fluid may be simultaneously pumped through the ion exchange module 45.

In this second mode, aqueous fluid is initially passed directly to the NMR spectrometer bypassing the ion exchanger material of the ion exchange module 45 via the bypass pipe 45a. The unfiltered sample is measured in the NMR spectrometer while simultaneously the volume of VinflUent of the aqueous sample fluid is pumped through the ion exchanger material in the ion exchange module 55 and bypassing the NMR spectrometer 44 via bypass pipe 44a and to the waste.

Thereafter the valve is switched to its second setting and elution fluid is passed through the ion exchange module 45 to elute the captured ions. From the ion exchange module 44 the elution fluid is pumped to the NMR spectrometer 44 for analysis by NMR measurements.

In the sixth embodiment the NMR system comprises both anionic and cationic exchanger material.

The sixth embodiment of the NMR system of the invention shown in Fig. 9. comprises an aqueous sample fluid inflow pipe 51 for inflow of an aqueous sample fluid The inflow pipe 51 is branching into a valve A and a valve B. A pipe for feeding elution fluid for cationic elution is leading from a cationic elution fluid reservoir 57a to the valve A and a pipe for feeding elution fluid for cationic elution is leading from a cationic elution fluid reservoir 57b to valve B. From valve A a pipe with a pump A is leading to a cation exchange module 55a and further to an NMR spectrometer 54 with a bypass pipe 54a and a waste. From the valve B a pipe with a pump B is leading to an anion exchange module 55b and further to the NMR spectrometer 54 with the bypass pipe 54a and to a waste.

The pump A and pump B are advantageously of peristaltic type allowing quantification of the flow.

In use a volume of solvent A of the aqueous sample fluid is pumped through the cation exchange module 55a. The valve B may be closed for sample inflow. The aqueous sample fluid is bypassed by the NMR spectrometer 54 and pumped out to waste.

Thereafter the valve A is switched and a volume Veiution A of cationic elution fluid is pumped from the cationic elution fluid reservoir 57a and through the cation exchange module 55a for elution of the captured ions and the cationic elution fluid is pumped further to the NMR spectrometer for NMR reading. Simultaneously the valve B is opened for sample inflow and a volume of VinflUent B of the aqueous sample fluid is pumped through the anion exchange module 55b. This may be performed simultaneously with the reading of the cationic elution fluid because the aqueous sample fluid is bypassed by NMR spectrometer 54 and pumped out to waste.

Thereafter valve A and valve B are switched and a volume Veiution B of anionic elution fluid is pumped to elute the ion exchanger material in the anion exchange module 55b and for NMR reading while fresh aqueous sample fluid is pumped to the a cation exchange module 55a, and so on the circle may be repeated for as long as desired.

The seventh embodiment of the NMR system of the invention shown in FIG. 10 is a variation of the fifth embodiment. The NMR system of the seventh embodiment differs from the NMR system of the fifth embodiment in that it comprises an elution fluid gradient mixing system comprising a pipe 37a leading from an elution fluid concentrate reservoir to a gradient mixer 32 and a pipe 37b leading from a water reservoir to the gradient mixer 32. The gradient mixer provides a homogeneous elution fluid which is pumped via the elution fluid inflow pipe 37 as described above. In addition, the elution fluid may be gradually or stepwise stronger (more acidic or more basic depending on the ion exchanger material and the ions to be eluted).

This embodiment allows eluting bound target ions having different bonding strength to the ion exchanger material sequentially using an eluent (e.g. NaCl / water) with increasing strength.

The eight embodiment of the NMR system of the invention shown in FIG. 11 comprises an aqueous sample fluid inflow pipe 61 for inflow of an aqueous sample fluid and an elution fluid inflow pipe 67b for inflow of an elution fluid, both inflow pipes 61, 67 lead to a valve A, comprising at least two settings, a first setting where fluid from the aqueous sample fluid inflow pipe 61 is passed through a pipe to an ion exchanger material in an ion exchange module 65 and a second setting where elution fluid is passed from the elution fluid inflow pipe 67b to the ion exchange module 65 for regenerating the ion exchanger material of the ion exchange module 65.

The ion exchange module 65 is arranged in a measuring zone of an NMR spectrometer 64. The ion exchange module 65 has an outflow pipe leading to a valve B. The valve B has a first setting where the fluid is passed from the ion exchange module outflow to a piston pump which pumps the fluids.

The valve B has a second setting which provides a flow path backwards from the piston pipe and to a reservoir not shown, such as a waste reservoir, a giant reservoir or a discharge reservoir.

The NMR system advantageously further comprises at least one flow analyzer as described above. As since the pump volume (space of the pump) and the amount of pump steps are known the piston pump may act as a flow analyzer.

In use the valve A is set in its first setting and valve B is set in its first setting. A volume of VinflUent of the aqueous sample fluid is pumped through the ion exchanger material in the ion exchange module 65 and to the space in the piston pump 68. Some of the aqueous fluid may remain in the pipe section between valve B and the piston pump 68 The valve B is switched and the piston pump is emptied to the waste. As mentioned above, the volume of VinflUent of the aqueous sample fluid may be pumped through the ion exchanger material in the ion exchange module 65 in several circles in particular where the volume of VinflUent of the aqueous sample fluid is larger than the pump volume of the pump.

The NMR spectrometer may be switched on to measure the ion exchanger material during enrichment (the capture of preselected ion type (s)).

This embodiment thereby allows quantizing amounts of multiple bound analytes (isotopes) during the enrichment process. In addition, it is possible to quantify amounts of bound analyte (s) by performing multi-isotope NMR analysis. Further it may be monitored when the ion exchanger material approaches saturation e.g. be watching when the bond strength of the ion exchanger material decreases. Thereby breakthrough may be avoided while simultaneously using the ion exchanger material very effectively.

After the NMR measurement, the ion exchanger material of the ion exchange module 65 may be regenerated by allowing elution fluid to flow through the ion exchanger material.

In an alternative NMR system the NMR system does not comprise elution fluid means for leading it to the ion exchange module 65. In this alternative embodiment disposable ion exchange modules are used. Thus after terminating a measurement circle the ion exchange module 65 is removed and replaced with a fresh ion exchange module 65.

The NMR spectrometer is connected to a not shown computer comprising a calibration map and programmed to calculate the concentration of the at least one preselected ion type and / or element thereof in the aqueous sample fluid. The computer is advantageously also programmed to operate the NMR system for carrying out the described method.

The elution profiles shown in Figs 12-15 are obtained by the following examples

Example 1: Boron enrichment from raw water 10 liters of raw water containing 10 ppb Boron are pumped through a strong base anion exchange resin having sufficient capacity for capturing boron.

Elution is being carried out with 0.25L 4% (1M) NaOH.

Overall volumetric enrichment factor is 40 (10 / 0.25) considering that the eluted Boron is distributed in elution volume.

Final concentration in eluted sample is determined to be 400 ppb Boron based on the assumption that the complete elution peak is dissolved in the used volume of elution volume. The elution profile is shown in fig. 12. 11B NMR analysis can be carried out for example to obtain: a) an entire elution profile assessing total Boron content in eluted sample (indicated by arrow 1). This requires a calibrated system. b) the time when maximum elution profile is or is to be expected (indicated by arrow 2). This requires a calibrated system. c) a collection of complete elution volume including released Boron, mixing and analyzing for Boron. The Boron concentration obtained this way divided by the volumetric enrichment factor gives the Boron content of the original sample.

Example 2: Heavy metal enrichment from wet scrubber effluents 20 liters of particle free, lime neutralized scrubber effluent containing 4 ppb As and 5 ppb They are led through a strong base anion exchange resin of sufficient capacity.

Elution is being carried out with 0.25L 20% NaCl.

Overall volumetric enrichment factor is 80 (20 / 0.25).

Final concentration in eluted sample is 320ppb As and 400ppb Se if complete elution peak is dissolved in used volume of elution volume. 75As, 77Se-NMR analysis can be carried out to show: a) throughout elution profile as shown in Figs. 13 assessment total As / Se content in eluted sample (arrow 1) b) the specific time when maximum of elution profiles are expected (arrow 2) c) a collection of complete elution volume including released target ions, mixing and analyzing. The concentration of As and Se obtained this way divided by the volumetric enrichment factor gives the As and Se content of the original sample.

Example 3: Enrichment and analysis of nitrate and ammonium in a system with separate anion and cation exchange resin. 20 liters of drinking water sample containing 1 ppm nitrate and 0.15 ppm ammonia are pumped through each of two separate anion / cation exchange resin beds of sufficient capacity for nitrate and ammonium e.g. as shown in FIG. 9th

Elution of nitrate bound on the anion exchange resin is carried out with 0.25L 4% (1M) NaOH. The elution fluid is being passed through the NMR unit and the amount of nitrate released is quantified.

Elution of ammonium bound on the cation exchange resin is being carried out with 0.25L 5% H2S04. The elution fluid is being passed through the NMR unit and the amount of ammonium released is quantified.

Overall volumetric enrichment factor is 80 (20 / 0.25).

Final concentration of nitrate in anion exchange resin elute is 80 ppm if complete elution peak is dissolved in used volume of elution volume.

Final concentration of ammonium in cation exchange resin elute is 12 ppm if complete elution peak is dissolved in used volume of elution volume.

The elution profile is shown in FIG. 14. NMR analysis of ammonium or nitrate can be carried out as explained in other examples.

Example 4: Enrichment and analysis of nitrite and nitrate in a gradient elution system 10 liters of drinking water sample containing 0.1 ppm nitrite and 1 ppm nitrate are pumped through an anion exchange resin bed of sufficient capacity for the bonding of relevant ions (Eg using the NMR system of Fig. 9). Nitrite typically has a lower selectivity coefficient than nitrate and will elute at lower strength of eluent (see Dowex Ion Exchange Resin - Technical Information)

Sequential elution of nitrite and nitrate bound on the anion exchange resin is being carried out with a gradient of 0-4% (1M) NaOH. The gradient elute is being led through the NMR unit and the amount of nitrite and nitrate released is quantified one by one.

Selectivity coefficients: N02- / 0H- = 24; NO3 / OH = 65.

The elution profile is shown in FIG. 15th

Claims (57)

1. A method of determining a concentration of at least one preselected ion type and/or an element of said preselected ion type in an aqueous sample fluid, the method comprises concentrating the preselected ion type of said aqueous sample fluid using ion exchanger material and subjecting the concentrated preselected ion type to NMR measurements using an NMR spectroscope, collecting NMR data from said NMR measurements and correlating the collected NMR data to calibration data to determine the concentration of said preselected ion type and/or said element of said preselected ion type in the aqueous sample fluid.

2. The method of claim 1, wherein the method comprises • providing said ion exchanger material comprising exchange sites for the at least one preselected ion type • passing a volume VinflUent of the aqueous sample fluid through the ion exchanger material; and • subjecting the ion exchanger material to said NMR measurements and determining the concentration of said preselected ion type and/or said element of said preselected ion type in the aqueous sample fluid based on the collected NMR data and the volume VinflUent of the aqueous sample fluid.

3. The method of claim 1, wherein the method comprises • providing said ion exchanger material comprising exchange sites for the at least one preselected ion type, • passing a volume VinflUent of the aqueous sample fluid through the ion exchanger material; and • stripping off adsorbed ions from the ion exchanger material using a volume Veiution of an aqueous elution fluid, • performing said NMR measurements on the elution fluid, and • determining the ion concentration in the aqueous sample fluid based on the ratio of the volume VinflUent of the aqueous sample fluid relative to the volume Veiution of the elution fluid, wherein the volume Veiution of the elution fluid is less than the volume VinfiUent of the aqueous sample fluid, preferably the volume Veiution of the elution fluid is up to about 50 % of the volume VinfiUent of the aqueous sample fluid, such as up to about 25 %, such as up to about 10 %, such as from about 0.0005 % to about 5 %.

4. The method of any one of the previous claims, wherein the at least one preselected ion type comprises at least one atom of an element selected from arsenic, antimony, boron, cadmium, chromium, cobalt, copper, lead, manganese, mercury, nickel, nitrogen, phosphor, potassium, selenium, silver, thallium, zinc or of any other of the transition metals or post transition metals.

5. The method of any one of the previous claims, wherein the at least one preselected ion type comprises a cation, preferably selected from metal cations, alkali metal cations, alkaline earth metal cations and/or poly atomic cations.

6. The method of any one of the previous claims, wherein the at least one preselected ion type comprises a cation selected from ammonium (NH4+), aluminium (Al3+), arsenic(As3+), arsenic (As5+), barium (Ba2+), boron (B3+), calcium (Ca2+), cadmium (Cd2+) chromium(III) (Cr3+), chromium(IV) (Cr4+), copper(I) (Cu+), copper(II)(Cu2+), iron(II) (Fe2+), iron(III) (Fe3+), lead(II) (Pb2+), lead(IV) (Pb4+), lithium (Li+), manganese(II) (Mg2+), manganese(III) (Mn3+), mercury(I) (Hg2+), mercury(II) (Hg2+2)silver (Ag+), natrium (Na+), strontium (Sr2+), tin(II) (Sn2+), tin(IV) (Sn4+) and/or zinc (Zn2+).

7. The method of any one of the previous claims, wherein the at least one preselected ion type comprises an anion, preferably selected from halogen ions, oxoanions, anions from organic acids, and/or polyatomic anions.

8. The method of any one of the previous claims, wherein the at least one preselected ion comprises an anion selected from aluminiumsilicate (AISiC>32') azide (N3“), bicarbonate (HCC>3‘), bromide (Br), (borate (BC>33‘), carbonate (C032 ), bisulfate ( HS04 ), bisulfite (HS03'), chlorate (CI03'), chloride(CI-), chromate Cr042'), cyanide (CN'), dichromate (Cr2072 ) dihydrogen phosphate (H2P04'), fluoride (F"), hydrogen phosphate (HP042'), iodide (Γ), Metasilicate (Si032'), nitrate (N03'), nitride (N3'), nitrite (N02‘), perchlorate (CI04"), permanganate (Mn04"), phosphate (P043"), silicate (Si04"4), sulfate (S042'), sulfide (S2'), sulfite (S032'), selenite (Se032') and/or selenate (Se042').

9. The method of any one of the previous claims, wherein the ion exchanger material is ion exchange resin, preferably the ion exchange resin comprises a support structure which is insoluble in the aqueous sample.

10. The method of claim 9, wherein the support structure is of a polymer material, preferably crosslinked polystyrene.

11. The method of claim 9 or claim 10, wherein the ion exchanger material comprises a support structure comprises functional groups bonded to the support structure, wherein the functional groups form ion exchanging sites for the at least one preselected ion type, the functional groups are for example for cationic sites selected from carboxylic acid groups or sulfonic acid groups, such as sodium polystyrene sulfonate or poly (acrylamido-N-propyltrimethylammonium chloride) or for anionic sites secondary, ternary and/or quaternary amino groups such as polyethylene amine or trimethylammonium groups.

12. The method of any one of claims 9-11, wherein the ion exchanger material is a chelating resin, preferably comprising functional groups selected from iminodiacetic acid, aminophosphonic, thiourea and/or 2-picolylamine.

13. The method of any one of claims 9-11, wherein the ion exchange resin is in the form of a membrane and/or in the form of a bed of beads.

14. The method of any one of the previous claims, wherein the amount of ion exchanger material is from about 0.0001 to about 0.1 L per L VinfiUent of the aqueous sample fluid, such as from about 0.0005 to about 0.01 L per L VinAuent of the aqueous sample fluid.

15. The method of any one of the previous claims, wherein the ion exchanger material comprises a cation exchanger material, an anion exchanger material or any combination or mixtures thereof.

16. The method of any one of the previous claims, wherein the ion exchanger material comprises two or more ion exchanging sub units arranged in parallel or in series, wherein the two or more ion exchanger sub units are equal or differ from each other with respect to size, shape and/or ion exchanger material.

17. The method of claim 16, wherein the ion exchanger material comprises said two or more ion exchanger sub units arranged in series, wherein the two or more ion exchanger sub units comprise at least one anion exchanger sub unit and at least one cation exchanger sub unit.

18. The method of claim 16, wherein the ion exchanger material comprises said two or more ion exchanger sub units arranged in parallel, wherein the two or more ion exchanger sub units comprise at least one anion exchanger sub unit and at least one cation exchanger sub unit.

19. The method of claim 16, wherein the ion exchanger material comprises said two or more ion exchanger sub unit arranged in parallel, wherein the two or more ion exchanger sub unit comprises mixed anion exchanger material and cation exchanger material.

20. The method of any one of the previous claims, wherein the volume of the aqueous sample fluid is selected to be less than a calculated or determined volume of the aqueous fluid for reaching breakthrough (throughput volume), preferably less than 80 % of or less of the calculated volume to ensure that breakthrough of the preselected ion type is not reached.

21. The method of claim 20, wherein the calculated volume of the aqueous fluid for reaching breakthrough volume of the aqueous sample fluid is obtained by estimating a concentration of the preselected ion type and calculating the volume of the fluid required for reaching breakthrough of the preselected ion type based on the estimated concentration of the preselected ion type.

22. The method of claim 20, wherein the determined volume of the aqueous fluid for reaching breakthrough is obtained by NMR measurement, preferably the breakthrough is determined by performing NMR measurement on the aqueous sample fluid after passing the ion exchanger material (the effluent), determining when a NMR signal caused by the preselected ion type is detected and determining the volume of the aqueous fluid for reaching breakthrough as the volume that has passed the ion exchanger material until the breakthrough.

23. The method of any one of the previous claims, wherein the volume VinAuent of the aqueous sample fluid is selected relative to the type and amount of ion exchanger material, preferably such that at least about 10 % of an exchange capacity of the ion exchanger material is used, preferably such that at least about 40 % of the exchange capacity of the ion exchanger material is used, more preferably such that from about 50 % to about 80 % of the exchange capacity of the ion exchanger material is used.

24. The method of any one of the previous claims, wherein the volume VinAuent of the aqueous sample fluid is from about 0.1 L to about 1000 L, such as from about 10 to about 500 L, such as from about 25 L to about 300 L.

25. The method of any one of the previous claims, wherein the ion exchanger material comprises an anionic ion exchanger material having a pKa value and the elution fluid having a pKa higher than the pKa value of the anionic ion exchanger material, preferably the elution fluid is an aqueous solution of caustic soda (NaOH), Caustic potash (potassium hydroxide KOH), Ammonia (NH3) Sodium carbonate (soda ash, Na2C03) and/or lime (calcium hydroxide, Ca(OH)2).

26. The method of any one of the previous claims, wherein the ion exchanger material comprises a cationic ion exchanger material having a pKa value and the elution fluid having a pKa lower than the pKa value of the cationic ion exchanger material, preferably the elution fluid is an aqueous solution of hydrochloric acid (HCI), Sulphuric acid (H2S04) nitric acid (HN03) acetic acid (CH3COOH) and/or citric acid (C6H807).

27. The method of any one of the previous claims 2-26, wherein the elution fluid is counter flowed through the ion exchanger material.

28. The method of any one of the previous claims 2-27, wherein the elution fluid is recirculated through the ion exchanger material preferably for two or more times and/or for a predetermined time, such as for 1 minute or more, such as for 10 minutes or more, such as up to one hour.

29. The method of any one of the previous claims 2-28, wherein the ion exchanger material is subjected to stirring at least for a selected time while in contact with the elution fluid.

30. The method of any one of the previous claims, wherein the elution fluid is passed directly from the ion exchanger material and into the NMR spectroscope for performing the NMR measurement(s).

31. The method of any one of the previous claims 2-30, wherein the elution fluid or at least a portion thereof is temporarily collected in an intermediate space prior to being passes to the NMR spectroscope for performing the NMR measurement(s), said intermediate space is preferably a space the piston pump for pumping the elution fluid to the NMR spectroscope.

32. The method of any one of the previous claims, wherein the ion exchanger material consists essentially of anion ion exchanger material and the volume Veiution of elution fluid is elution fluid for stripping off adsorbed anions from the anion exchanger material.

33. The method of any one of the previous claims 1-31, wherein the ion exchanger material consists essentially of cation exchanger material and the volume Veiution of elution fluid is elution fluid for stripping off adsorbed cation from the cation exchanger material.

34. The method of any one of the previous claims 1-31, wherein the ion exchanger material comprises both anion exchanger material and cation exchanger material, preferably in the form of two or more ion exchanger sub units and the volume Veiution of elution fluid is elution fluid for stripping off adsorbed cation from the cation exchanger material or the volume Veiution of elution is elution fluid for stripping off adsorbed anions from the anion exchanger material. 35 The method of any one of the previous claims 2- 31, wherein the ion exchanger material comprises both anion exchanger material and cation exchanger material and the method comprises • passing the volume VinflUent of the aqueous sample fluid through the ion exchanger material comprising said anion exchanger material and said cation exchanging resign • stripping off adsorbed anions and cations using electrodeionization from the anion and cation exchanger material using a volume Veiution of an aqueous anion+cation elution fluid, • performing the NMR measurements on at least one of the anion elution and the cation elution fluids using the NMR spectroscope wherein the volume Veiution of the anion+cation elution fluid is less than the volume VinfiUent of the aqueous sample fluid.

36. The method of any one of the previous claims wherein the method comprises performing a plurality of NMR measurements.

37. The method of any one of the previous claims wherein NMR measurements comprise reading of at least one NMR readable isotope comprised in said at least one preselected ion.

38. The method of any one of the previous claims wherein NMR measurements comprise reading of at least one NMR readable isotope, preferably the NMR measurements comprise reading a plurality of NMR, readable isotopes.

39. The method of any one of the previous claims wherein NMR measurements comprise NMR reading of one or more of the isotopes 10B, UB, 13C, 14N, 15N, 160, 19F 23Na, 27AI, 29Si 31P, 33S, 35CI, 37CI , and 39K, 41K, 43Ca, 47Ti, 49Ti, 50V, 51V, 53Cr, 55Mn, 57Fe, 59Co, 61Ni, 63Cu, 65Cu, 67Zn, 69Ga, 71Ga, 75As, 77Se,79Br, 81Br, 83Kr, 85Rb, 87Rb, 87Sr, 89Y, 91Zr, 93Nb, 95Mo, 97Mo, 105Pd, 107Ag, 109Ag, luCd, 113Cd, 117Sn, 119Sn, 115Sn, 121Sb, 135Ba, 137Ba 177Pb, 199Hg, 201Hg, 207Pb, preferably the method comprises a plurality of readings of one or more of 13C, 14N, 19F 23NA, 31P, 35CI, 37CI, 39K, 79Br, and 81Br.

40. The method of any one of the previous claims wherein NMR measurements comprise NMR reading of one or more heavy metal isotopes, such as isotopes of Pb, Fig and/or Cd.

41. The method of any one of the previous claims wherein NMR measurements comprise a plurality of consecutive NMR readings of one or more NMR readable isotopes preferably comprising at least one of 13C, 14N, 19F 23Na, 31P, 35CI,39K, 79Br, and 81Br.

42. The method of any one of the previous claims wherein NMR measurements comprise NMR reading of 35CI and/or 37CI and determining the concentration of one or more Cl containing ions in the aqueous sample fluid.

43. The method of any one of the preceding claims wherein the concentration of the at least one preselected ion type in the aqueous sample fluid is determined by generating NMR data from said NMR measurements and correlating said NMR data calibration data and determining the concentration of the preselected ion type(s) and/or the element(s) thereof in the aqueous sample fluid, preferably the at least one preselected ion type in the aqueous sample fluid is determined by generating NMR data from said NMR measurements and correlating said NMR data calibration data and determining the concentration of the preselected ion type(s) in the used elution fluid and determining the concentration of the preselected ion type(s) in the aqueous sample fluid by adjusting for the proportion of the volume VinAuent relative to the volume Veiution·

44. The method of any one of the preceding claims, wherein the method comprises determining the concentration of at least one element of said at least one ion, said at least one element is preferably selected from arsenic, antimony, boron, cadmium, chromium, cobalt, copper, lead, manganese, mercury, nickel, nitrogen, phosphor, potassium, selenium, silver, thallium or zinc.

45. The method of any one of the preceding claims, wherein the method comprises performing NMR reading on unfiltered (not passed through the ion exchanger material) aqueous sample fluid at predetermined interval.

46. The method of any one of the preceding claims, wherein the NMR measurements comprise simultaneously subjecting the elution fluid to a magnetic field B, and a plurality of pulses of radio frequency energy E (RF pulses) and receiving relaxation signals from excited nuclei, preferably the relaxation signals comprise a free induction decay (FID) spectrum.

47. The method of any one of the preceding claims wherein the NMR measurements comprise subjecting the elution fluid to proton decoupling pulses and/or polarization pulses during at least a part of the NMR reading.

48. The method of any one of the preceding claims wherein the NMR measurements comprise enhancing signal to noise of the data spectra by subjecting the elution fluid to a pulse configuration providing polarization and/or proton decoupling of atoms of one or more compound in the sample.

49. The method of any one of the preceding claims wherein the NMR measurements comprise enhancing signal to noise of the data spectra by subjecting the elution fluid to a pulse configuration comprising at least one of DEPT (Distortionless Enhancement by Polarization Transfer), DEPTQ (DEPT with retention of Quaternaries), HSQC (Heteronuclear Single Quantum Coherence), INEPT (Insensitive Nuclei Enhanced by Polarization Transfer), BIRD (Bilinear Rotation Decoupling pulses), TANGO (Testing for Adjacent Nuclei with a Gyration Operator) or NOE (Nuclear Overhauser Effect).

50. The method of any one of the preceding claims wherein the NMR measurements are performed in a magnetic field of up to about 25 Tesla, such as from about 0.3 Tesla to about 15 Tesla, such as from 0.3 to about 2.5 Tesla, such as up to about 1.5 Tesla.

51. The method of controlling a quality parameter of claim 44 or 45, wherein the aqueous sample fluid is drinking water; waste water, such as industrial waste water, hospital waste water or municipal waste water; lake water; swimming pool water or aquaculture water.

52. A NMR system suitable for determining a concentration of at least one preselected ion type and/or an element thereof in an aqueous sample fluid, the system comprises ion exchanger material, a NMR spectrometer, a digital memory storing a calibration map comprising calibrating data for calibrating NMR data obtained by the NMR spectrometer and a computer programmed to analyze the NMR data obtained by the NMR spectrometer using the calibration map and to perform a determination of the concentration of said at least one preselected ion.

53. The NMR system of claim 52, wherein the NMR system comprises an ion exchanging apparatus comprising ion exchanger material, wherein said ion exchanging apparatus is coupled to said NMR spectrometer, such that the ion exchanger material is arranged in a reading zone of the NMR spectrometer or said ion exchanging apparatus is coupled to said NMR spectrometer to provide a liquid flow path from said ion exchanger material to a reading zone of said NMR spectrometer.

54. The NMR system of claim 52 or claim 53, wherein the ion exchanging apparatus is a co-flow apparatus wherein the aqueous sample fluid and the elution fluid are passing the ion exchanger material with same flow direction.

55. The NMR system of claim 52 or claim 53, wherein the ion exchanging apparatus is a counter-flow apparatus wherein the aqueous sample fluid and the elution fluid are passing the ion exchanger material with opposite flow direction.

56. The NMR system of claim 52 or claim 53, wherein the ion exchanging apparatus is a electrodeionization apparatus and the ion exchanger material is a mixture of anion resin and cation resin, the electrodeionization apparatus preferably comprises a stack of adjacent and alternately arranged ion exchanger material chambers and elution fluid chambers, separated by alternately arranged cation exchange membranes and anion exchange membranes and a set of DC electrodes located on either sides of the stack of chambers.

57. The NMR system of any one of claims 52-56, wherein the NMR system is configured for performing the method as claimed in any one of claims 1-51, preferably the computer is programmed to control the NMR spectrometer, the ion exchanging apparatus and at least one pump for performing the method as claimed in any one of claims 1-51.

58. The NMR system of any one of claims 52 - 57, wherein the system further comprises a flow analyzer, said flow analyzer is preferably adapted for determining at least one of the amount of the aqueous sample fluid flowing through the ion exchanger material, the amount of the elution fluid flowing through the ion exchanger material, the velocity of the aqueous sample fluid flowing through the ion exchanger material, the velocity of the aqueous sample fluid flowing through the ion exchanger material.