WO2018087549A1

WO2018087549A1 - Fluid preparation with ultraviolet light

Info

Publication number: WO2018087549A1
Application number: PCT/GB2017/053376
Authority: WO
Inventors: Matthew MOWLEM; Sebastian Steigenberger; Socratis LOUCAIDES; George Dadd
Original assignee: Natural Environment Research Council
Priority date: 2016-11-10
Filing date: 2017-11-09
Publication date: 2018-05-17
Also published as: GB2556039A

Abstract

A device suitable for preparing fluid samples for chemical analysis, the device comprising: an ultraviolet light source; an ultraviolet reflector arranged to reflect ultraviolet light emitted from the ultraviolet light source; an ultraviolet transmitter being located between the ultraviolet light source and the ultraviolet reflector so as to transmit ultraviolet light emitted from the ultraviolet light source to the ultraviolet reflector; and a fluid path, at least a portion of the fluid path being located between the ultraviolet transmitter and the ultraviolet reflector. In use, a fluid containing one or more analyte chemical species flows along the fluid path and the emitted and reflected ultraviolet light cause degradation of at least one of the analyte chemical species therein.

Description

FLUID PREPARATION WITH ULTRAVIOLET LIGHT

The present invention relates to a device for use in sensing and measurement of chemical species in a fluid, such as water. More particularly, it relates to a device, e.g. a photo-oxidation device, for the preparation of fluid samples for chemical analysis.

Water is a precious natural resource. In order to help preserve, protect and/or manage this resource effectively, it is important to be able to understand and monitor it, e.g. by obtaining reliable information on water quality and content. For instance, it may be desirable to sense and measure chemical species within a body of water such as an ocean, a sea, an estuary, a river, a reservoir, a canal, a lake or a pond, since changes in concentration of one or more chemical species may indicate changes in water quality and/or in the prevailing environmental conditions for plants and animals that live in the water.

According to a first aspect of the present invention there is provided a device suitable for preparing fluid samples for chemical analysis, the device comprising:

an ultraviolet light source ;

an ultraviolet reflector arranged to reflect ultraviolet light emitted from the ultraviolet light source;

an ultraviolet transmitter being located between the ultraviolet light source and the ultraviolet reflector so as to transmit ultraviolet light emitted from the ultraviolet light source to the ultraviolet reflector; and

a fluid path, at least a portion of the fluid path being located between the ultraviolet transmitter and the ultraviolet reflector;

wherein, in use, a fluid containing one or more analyte chemical species flows along the fluid path and the emitted and reflected ultraviolet light cause degradation of at least one of the analyte chemical species therein.

Advantageously, the exposure of the fluid to ultraviolet light may be improved, since the fluid flowing along the fluid path will be exposed, in use, to ultraviolet light emitted from the ultraviolet light source before and after the ultraviolet light is reflected by the ultraviolet reflector. Ultraviolet (UV) light has a wavelength of from 10 nm to 380 nm. UV light can be employed to generate highly reactive hydroxyl radicals ( OH) , which are strong oxidising agents. The hydroxyl radicals react with organic compounds to fragment them and generate small inorganic molecules. This is sometimes known as Advanced Oxidative Processes (AOP). Without being bound by theory, the inventors propose that the use of UV light photo-oxidises organic compounds and thereby renders them suitable for subsequent chemical analysis. Thus, the device may be an ultraviolet photo-oxidation device. It will be understood that the ultraviolet reflector (the UV reflector) and the ultraviolet transmitter (the UV transmitter) are made from different materials.

UV reflector The UV reflector may be highly reflective to UV in order to maximise the reflection of UV light onto the fluid path. In embodiments, the ultraviolet reflector may reflect at least 50%, at least 60%, at least 70%, at least 80% or at least 90% of UV light incident on its surface. Ideally, the nature of the reflection is highly diffuse so as to help to ensure even exposure to UV.

The UV reflector may comprise or consist essentially of a material that: is preferably hydrophobic such that residues of fluid samples are repelled and do not tend to remain in the device; is easily formed into the required shape for cost effective manufacture; is chemically inert such that the fluid sample is not contaminated by the material; and/or is highly resilient to UV degradation. For example Polytetrafluoroethylene (PTFE) provides all these benefits. A UV reflector may additionally comprise a surface that is metallised to further minimise absorption losses.

In embodiments, the ultraviolet reflector may comprise polytetrafluoroethylene (PTFE) such as the PTFE sold under the brand name Teflon®. As well as reflecting the UV light, PTFE has the benefit of a high melting point and good thermal insulating properties. This means that the components can be located closer together, and can consequently provide a more compact device. In other embodiments , the ultraviolet reflector may comprise a polished solid, such as a metal, a metal oxide or a metal nitride. In embodiments, the device may comprise more than one UV reflector.

In embodiments, the UV reflector(s) may substantially surround the UV light source e.g. the UV reflector may have radial symmetry and/or may be tubular. Surrounding the UV light source may provide a benefit of total internal reflection of the UV light that is emitted. Hence, the UV light becomes trapped within the device and more efficiently oxidises chemical specifies in the fluid path.

In other embodiments the UV light source may substantially surround the UV reflector.

UV transmitter

The UV transmitter is transparent to ultraviolet light. In embodiments, the UV transmitter may transmit at least 50%, at least 60% , at least 70%, at least 80% or at least 90% of UV light incident on its surface.

A disadvantage of using glass or quartz or their variants is that silicon may evolve from the surface in contact with the fluid sample which may cause interference in some chemical measurements (e.g. determination of phosphate with the Molybdenum Blue Assay). To prevent this problem, alternative materials may be used, or coatings or layers (not of glass or quartz) may be used to prevent silicon leaching.

In embodiments, the UV transmitter may comprise or consist essentially of: sapphire, nano polycrystalline alumina (PCA), aluminum oxynitride (ALON), magnesium aluminate spinel, calcium fluoride, and/or quartz (fused silica). In particular embodiments, the UV transmitter may comprise sapphire and/or quartz (fused silica).

In embodiments, the UV transmitter may comprise a base material and a second material that is coated on the first material. For example, the UV transmitter may comprise or consist essentially of: fused silica coated with alumina (e.g. by physical vapour deposition, PVD); fused silica coated with zinc sulfide (e.g. by chemical vapour deposition, CVD); or fused silica coated with cyclic olefin co-polymer (COC) (e.g. by dip coat). In embodiments the UV transmitter may substantially surround the UV light source e.g. the UV reflector may have radial symmetry and/or may be tubular. Surrounding the UV light source may provide a benefit of protecting the UV source. In this way a UV transmitter (especially a tubular UV transmitter) may serve as a pressure housing. In one embodiment, the UV transmitter may comprise or consist essentially of sapphire. The sapphire typically may be synthetic sapphire, commonly known as sapphire glass. Sapphire glass is transparent to wavelengths of light from 150 to 5500nm. Moreover, the use of sapphire may be beneficial since it provides little or no interference. An advantage of sapphire is that it can be employed at high pressures, e.g. in deep sea locations either in pressure balanced designs or where large differential pressure occurs across the sapphire. Another advantage of sapphire is that it does not interfere with chemical measurements by introducing silicon into the fluid to be analysed. A drawback of sapphire is that it is difficult to shape and so it is commonly available in planar sheets or as linear (straight) tubes only.

In another embodiment, the UV transmitter may comprise quartz. An advantage of quartz is that it can be employed at high pressures, e.g. in deep sea locations either in pressure balanced designs or where large differential pressure occurs across the quartz. A disadvantage of a quartz tube is that it can cause interference with chemical measurements by introducing silicon into the fluid to be analysed.

Fluid path

In embodiments, the fluid path may have an internal diameter of up to or at least 0.5mm, up to or at least 1mm, up to or at least 1.5mm, up to or at least 2mm, up to or at least 2.5mm, up to or at least 3mm, up to or at least 3.5mm, up to or at least 4mm, up to or at least 4.5mm and/or up to or at least 5mm.

In embodiments the fluid path may comprise a linear (straight), serpentine or coiled portion that is located between the UV reflector and the UV transmitter. In embodiments, the ultraviolet transmitter may be a tube that defines the fluid path therein, i.e. the UV reflector is separate from the transmitter and does not define the fluid path. The tube may be linear (straight) at least in part and/or serpentine at least in part.

In embodiments, the device may comprise more than one tube, at least a portion of each tube being located between the ultraviolet light source and the ultraviolet reflector, each tube being transparent to ultraviolet light.

In embodiments, the UV transmitter tube may comprise a coiled portion arranged around the ultraviolet light source. Advantageously, by being for example coiled or serpentine, the portion of the tube located between the ultraviolet light source and the ultraviolet reflector may provide a relatively long and/or tortuous path for the fluid to flow along. Hence, the length of time that the fluid is exposed to the UV light may be increased. As a consequence, for example, a lower power UV light source could be used and/or the device could be operated at a higher flow rate, thereby preparing fluid samples for chemical analysis using less energy and/or more quickly. In embodiments, the UV transmitter may comprise a single linear tube. Alternatively, the UV transmitter may comprise a series of linear tubes arranged around the ultraviolet light source. This may be particularly useful when the UV transmitter tubes are sapphire, since sapphire cannot be readily shaped into a coil. The tube may have an internal diameter of up to or at least 0.5mm, up to or at least lmm, up to or at least 1.5mm, up to or at least 2mm, up to or at least 2.5mm, up to or at least 3mm, up to or at least 3.5mm, up to or at least 4mm, up to or at least 4.5mm and/or up to or at least 5mm. In embodiments, the ultraviolet transmitter and the ultraviolet reflector may together define at least partially the fluid path, e.g. the fluid path may be defined by at least two parts that are made from dissimilar materials and pressed and held together. One of the two parts may comprise or consist essentially of the ultraviolet transmitter and the other of the two parts may comprise or consist essentially of the ultraviolet reflector. This provides advantages in some circumstances over a device comprising a UV transmitter tube. The UV light travels from the source through a single wall of the UV transmitter to the sample and then to the reflector. If a UV transmitter tube is employed then the UV light must travel through a second wall of the UV transmitter before reaching the reflector. Hence, more UV may be absorbed in the sample, rather than by the device.

In embodiments, the ultraviolet reflector may have a channel (e.g. a groove) therein. The reflector typically comprises a material, which is more readily machined than the transmitter. For instance, PTFE is more easily shaped than sapphire or quartz.

In embodiments, the channel may be helical at least in part. In this way, the fluid path can be defined using a tubular UV transmitter which seals the channel.

In embodiments, the channel lies in a single plane. In this way the fluid path can be defined using a planar UV transmitter which seals the channel. Such channels may be linear or serpentine or comprise linear or serpentine portions.

In embodiments, the ultraviolet reflector may be tubular and the ultraviolet transmitter may be tubular. In this way the tubular UV transmitter can fit inside the tubular UV reflector or the tubular UV reflector may fit inside the tubular UV transmitter.

In other embodiments the ultraviolet reflector may be planar and the ultraviolet transmitter may be planar. In this way the planar parts may lie flush against each other.

Ultraviolet light source

In embodiments, the ultraviolet light source may comprise a low pressure ultraviolet light source, e.g. one mercury vapour lamp, a xenon based lamp, a deuterium based lamp, a flash lamp or a gas LASER. Alternatively one or more light emitting diodes (LEDs) or solid state LASERs may be preferred for use, particularly in situ, since an LED can be easily powered by batteries and typically generates less heat than a mercury lamp. Light emitting diodes may beneficially be used as the UV light source with the significant advantage that they are made from solid material and do not contain pockets of gas, thereby giving them more structural integrity than a UV light bulb for example. This solid property of LEDs means that they are well configured to survive the pressure exerted upon them during subsea deployment thereby removing the need to protect them with a pressure housing.

Advantageously, there may be more than one UV light source. There may be a variety of arrangements of a plurality of UV light sources to maximise the exposure of the fluid sample to UV light; for example the UV light sources may be arranged in a rectangular array or a circular pattern. They may also be arranged facing at different angles.

Lenses may be included with the UV light source(s) in order to beneficially concentrate the UV light onto the fluid thereby ensuring that the UV light energy is dissipated more substantially within the fluid and not absorbed within other components of the device thereby improving the power efficiency of the device.

The UV light source(s) may be configured with a heatsink in order to dissipate heat from the location of the heat source and thereby reduce unwanted changes, due to temperature, of the dimensional and structural properties of any of the components within the device. The said heatsink may be configured to radiate, conduct, or convect heat away from the UV light source(s) using a fluid, or a solid medium and that heat conductor may be arranged to transfer heat into the surrounding water in which the device is immersed or into the fluid sample if advantageous for photo - oxidation efficiency.

In embodiments the ultraviolet light source may have a power at a UV wavelength of at least 0.3, 0.5, 1 , 1.5 or 2mW and / or no more than 20000, 8000, 3000, 2000, 1000, 500, 100, 50, 10, 5 or 3mW. It will be understood that it is the total power that is relevant. Hence, if three LEDs are employed and each has a power of 0.5mW, then the power of the UV light source is 1.5mW. In embodiments, the ultraviolet light source may have an output at a UV wavelength of at least 0.5, 1 , 1.5 or 2mW/cm² and / or no more than 100, 50, 10, 5 or 3mW/cm² lmW/cm² as measured a small distance from the light bulb, ¾ inch. In embodiments, the ultraviolet light source may comprise a source of ultraviolet light having a wavelength of at least lOnm and/or up to 380nm. The ultraviolet light source may comprise a source of ultraviolet light having a wavelength of up to or at least lOOnm, up to or at least 150nm and/or up to or at least 280nm. In embodiments, the ultraviolet light source may have a main emission line at 254nm. The skilled person may select the optimal wavelength depending on the conditions. For example, a shorter wavelength may be optimal in a vacuum whereas this may not be practical in real systems where there is absorption (e.g. oxygen, water vapour, glass). In embodiments the ultraviolet light source may have a wavelength of at least 150nm and no more than 250nm.

Device

In embodiments the device comprises restraining means to prevent thermal expansion, at least of the UV reflector. In embodiments the restraining means may comprise a housing, which is capable of withstanding high pressure. For example, the device may comprise a stainless steel, titanium alloy, aluminium alloy, Inconel, bronze or composite material outer housing.

In embodiments, the device may be configured to be connectable to a chemical sensor and/ or analyser, e.g. a microfluidic chemical sensor and/or analyser such as a lab-on- chip (LOC) device. Such devices must be compact. In other embodiments, the device may be configured to process samples (for example, in a sample bottle, syringe, bag or tube) that can be analysed later when transferred to a chemical sensor or analyser. The device can be considered to have a maximum diameter (width) and a length, the diameter (width) and the length being mutually perpendicular. In embodiments, the device may have a maximum diameter of no more than 50, 40, 30, 20, 10, 5, 3, 2 or lcm. In embodiments, the device may have a length of no more than 50, 40, 30, 20, 10, 5, 3, 2 or l cm. In one embodiment the device may have a maximum diameter of no more than 2cm and a maximum width of no more than 2cm. In some embodiments the device can be considered to have a first end and an opposite second end. In use in those embodiments, a fluid may enter the device at the first (input) end and exits the device at the second (output) end. The device of the first aspect may be employed in situ , temporarily, semi-permanently or permanently. For example, it could be located within a body of water for a predetermined period of time (e.g. several days, weeks, months or longer) such as an ocean, a sea, an estuary, a river, a reservoir, a canal, a lake or a pond. In other embodiments, the device may be employed in a laboratory. In embodiments, the device may be portable. The device may for example be a handheld device.

The invention also resides in a system comprising two or more devices in series or in parallel. This allows a greater volume of fluid to be processed within a given time. The invention may also reside in a casing containing the device. The casing may be sufficiently strong to withstand subsea deployment.

According to a second aspect of the present invention there is provided a process for preparing a fluid sample for chemical analysis, the process comprising

providing a fluid comprising an analyte chemical species; and

passing the fluid along the fluid path of the device of the first aspect such that the emitted and reflected ultraviolet light cause degradation of at least one of the analyte chemical species. The comments above in relation to the first aspect of the invention apply equally to the second aspect of the invention and vice versa.

It will be understood that the fluid enters the device at a first end of the fluid path and exits the device at a second end of the fluid path.

In embodiments, the fluid may be a liquid e.g. water or an aqueous solution. In embodiments the fluid may be a saline aqueous fluid (e.g. it contains NaCl). The process of the invention may be particularly useful for seawater. In embodiments the fluid or fluid sample may additionally comprise polyvinylpyrrolidone (PVP). PVP is a water-soluble polymer made from the monomer N-vinylpyrrolidone. The process may comprise the preliminary step of adding PVP to the fluid. In a series of embodiments, the fluid may comprise at least 0.0001 %, at least 0.001 % , at least 0.005%, at least 0.01 % , at least 0.05%, at least 0.1 % or at least 0.5% PVP and/or no more than 1 % , no more than 0.5% , no more than 0.1 %, no more than 0.05% , no more than 0.01 %, no more than 0.005%, no more than 0.001 % or no more than 0.0005% PVP. All percentages are weight by volume (w/v). The inventors propose that PVP is especially useful in the molybdenum blue assay for phosphates, arsenates and germanates. PVP is considered to reduce the sensitivity of the assay to silicates. Silicates may be generated in the sample due to the dissolution of quartz.

It will be understood that an analyte chemical species is a chemical species which is of interest for analysis. In embodiments, the analyte chemical species may comprise organic compounds. Hence, photo-oxidation may convert the organic compounds to inorganic compounds. Some assays are more effective for inorganic compounds than for organic compounds. For example, the molybdenum blue assay is the standard method for determining the concentration of phosphate in seawater.

In embodiments the analyte chemical species comprise phosphorus, e.g. organophosphorus compounds. Hence, an organophosphorus compound may be converted to an inorganic compound by UV degradation. The resulting inorganic phosphorus compound (e.g. phosphate) can then be analysed by various methods, including the molybdenum blue assay.

In embodiments, the analyte chemical species may comprise nitrogen, e.g. organonitrogen compounds. Hence, an organonitrogen compound may be converted to an inorganic compound by UV degradation. The resulting inorganic nitrogen compound (e.g. nitrate) can then be analysed by various assays , such as the Griess assay. In embodiments, the analyte chemical species may be organically-bound, e.g. the analyte chemical species may comprise organically-bound (trace) metals or organically-bound arsenic. UV degradation thereby releases the target (inorganic / metal) chemical species for subsequent chemical analysis. In embodiments, the analyte chemical species may be a metal in a reduced form for which the assay has poor sensitivity, e.g. the analyte chemical species may be arsenic in its lower oxidation state (As(III)). UV oxidation thereby oxidises the target chemical species for subsequent chemical analysis.

In embodiments, the process may additionally comprise subjecting the fluid sample to subsequent chemical analysis. In embodiments , the fluid may be passed into a first end of the fluid path, pass through the fluid path, exit a second end of the fluid path and the fluid or a sample thereof may then be transferred to a chemical sensor and/or analyser, e.g. a microfluidic chemical sensor and/or analyser. The chemical sensor and/or analyser may be in fluid communication with the s econd end of the fluid path.

In embodiments, the process may be carried out in situ, e.g. within a body of water such as an ocean, a sea, an estuary, a river, a reservoir, a canal, a lake or a pond, optionally for a predetermined and/or extended period of time.

According to a third aspect of the present invention there is provided a system comprising the device of the first aspect and a chemical sensor and/or analyser, wherein the chemical sensor and/or analyser is disposed downstream of, and in fluid communication with, the device of the first aspect. The chemical sensor and/or analyser may comprise a microfluidic sensor and/or analyser. The chemical sensor and/or analyser may be a component of a lab -on-chip device.

In order that the invention may be well understood, it will now be described by way of example only with reference to the accompanying drawings, in which:

Figure 1A and IB are a pair of cross-sections of a device in accordance with an embodiment of the invention;

Figure 2 is an isometric view of a device in accordance with an embodiment of the invention in which a portion has been cut away to illustrate the structure;

Figure 3 is an isometric view of a device in accordance with an embodiment of the invention;

Figure 4A shows an isometric view of a device in accordance with an embodiment of the invention, figure 4B shows a cross -section of the device and figure 4C shows an isometric view of the device with a portion cut away to illustrate the structure ; and Figure 5 is a cross-section of a device in accordance with an embodiment of the invention.

Referring to figures 1A and IB , there is provided a cross-section of a photo-oxidation device 10, which is substantially cylindrical. The device 10 comprises a UV source 12 which irradiates a helical fluid path 14 that is defined by a first part 16 and a second part 18. The UV source is surrounded by the first part 16, which is a tube of UV transparent material e.g. sapphire, nanopolycrystalline alumina (PCA), aluminium oxynitride (ALON) , magnesium aluminate spinel, or calcium fluoride.

Advantageously, the UV source 12 is substantially exposed to the air such that the build-up of heat within the device is reduced with the advantage that unwanted effects of heating, such as thermal expansion and degradation of the materials, is minimised. In an alternative embodiment of the present invention, another fluid, such as an oil, can be used to dissipate heat.

The second part 18 is tubular with a helical channel (or thread) on its inner surface. The second part 18 is a highly reflective material e.g. PTFE. This maximises the reflection of the UV light onto the fluid path since total internal reflection takes place . PTFE has particular benefits: the nature of the reflection is highly diffuse so as to help to ensure even exposure to UV; it is hydrophobic such that residues of fluid samples are repelled and do not tend to remain in the device; it is easily formed into the required shape for cost effective manufacture; it is chemically inert such that the fluid sample is not contaminated; and it is highly resilient to UV degradation. The internal surface of the second part 18 may be metallised to further minimise absorption losses.

The first and second parts 16, 18 are sized so that the outer surface of the first part 16 is in contact with the inner surface of the second part 18. The fluid path 14 is sealed along the interface of the two parts 16, 18. The fluid path has an inlet 20 and an outlet 22.

The device 10 comprises an outer housing 24, which is made from a stiff, strong and resilient material with a lower thermal expansion coefficient than polymeric materials such as PTFE, such as stainless steel, titanium alloy, aluminium alloy, Inconel, bronze or composite material for example. The outer tube housing 24 serves as restraining means to prevent thermal expansion. The housing may be assembled around the second part 18 such that it exerts an inward pressure on the first part 16, by providing a tight interference fit which is pre -stressed. The housing 24 thereby prevents unwanted thermal expansion over a wide temperature range and causes the first and second parts 16, 18 to be pressed together more firmly. This improves the resilience of the fluid seal to temperature and pressure change.

The use of a resilient UV transmissive material 16, e.g. sapphire, is particular useful for subsea deployment since it helps to protect electronic components, such as the UV light source 12 from elevated ambient pressure as experienced in the deep sea. The UV transmissive material may constitute a pressure vessel and may be configured to withstand the ingress of fluid. In use a sample to be analysed enters the device 10 at the input 20, flows along the helical fluid path 14 where it is irradiated to oxidise chemical species therein, and then flows out of the device from the output 22.

Referring to figure 2, there is shown a schematic diagram of a device 30 where a section has been cut away to show the structure. This device 30 is similar to the device of figure 1 in that a UV source 32 irradiates a helical fluid path 34. However, in this example the UV source (a plurality of LEDs) 32 is located on the outside and thereby substantially surrounds the helical fluid path 34. The helical flow path is defined by two parts 36, 38. The first part 36 is a linear sapphire tube and the second part 38 is made from PTFE and located inside the first part 36. The second part 38 has a helical channel in its outer surface ; the first and second parts are pressed together to seal the fluid path 34. In use fluid enters the device 30 via an input 38, flows along the fluid path 34 where it is irradiated by the LEDs 32, and exits via an output 39.

Referring to figure 3 there is shown a device 40 comprising a series of LEDs (UV light source) 42 arranged to irradiate a serpentine fluid path 44. The fluid path 44 is formed from two parts 46, 48. The first part 46 is a (planar) sheet of sapphire glass, which is highly transparent to UV. The second part 48 is made from PTFE and comprises a channel in its surface. The first part 46 encloses the channel in the second part 48 to form the fluid path 44. The fluid path 44 comprises a series of linear portions in a zig-zag like arrangement. This allows the fluid path 44 to occupy the greatest possible volume, very close to the LEDs 42 thus maximising exposure and thereby increasing the extent of degradation of the analyte. In use fluid flows into the device 40 via an input (not visible in this view), flows along the fluid path 44 and exits from an output 49.

Referring to figure 4A, figure 4B and figure 4C, there is shown an elongate photo- oxidation device 50, having a UV light source 52 that is substantially surrounded by a fluid path that is formed using six interconnected linear tubes 54. The tubes 54 are held between a first manifold 56 and a second manifold 58. The manifolds 56, 58 are configured in order to connect the tubes 54 in a way that creates an elongate and continuous fluid path. The first manifold 56 comprises two parallel parts 56a, 56b which are pressed together and the second manifold comprises two parallel parts 58a, 58b which are pressed together.

The device 50 has an inlet 60 and an outlet 62 formed in the first manifold 56 in this instance. In other embodiments the inlet could be located in one manifold and the outlet in the other etc. The inlet 60 and outlet 62 may be configured to allow fluid connection using a fluid screw fitting, for example.

The device 50 includes a cylindrical reflector 64 which surrounds the UV light source 52 and the tubes 54 for the purpose of reflecting UV light back onto the fluid contained within the tubes 54.

The device 50 is pressed or held together using washer plates 66, 68 which are clamped and pressed together using nuts and bolts in one or more locations .

Referring to figure 5, there is provided a photo-oxidation device 70 in accordance with an embodiment of the invention. The device 70 comprises a housing 72 having an internal cavity 74. The housing 72 has an outer diameter dj of ~42mm and a height h of ~55mm. Within the internal cavity 74, there is disposed a UV lamp 76 with an optical output of 1.5mW/cm² at 254nm. One or more walls 78 defining the internal cavity 74 comprise at least one UV reflector comprising Teflon®. The internal cavity 74 may be substantially cylindrical, with the UV lamp 76 being disposed on a central, longitudinal axis of the internal cavity 74. The UV reflector(s) may be arranged to surround substantially the UV lamp 76.

A quartz tube 80 having a first end 82 and a second end 84 passes through the internal cavity 74. The first end 82 and the second end 84 are each located outside the housing 72. Within the internal cavity 74, a portion of the quartz tube 80 is arranged as a coil. The coil has a length 1 of 21 mm and an outer diameter d₂ of 14.5mm. The UV lamp 76 is located within the coil. The coil is located between the UV lamp 76 and the UV reflector(s). The quartz tube 80 has an internal diameter of ~ 1.5mm.

In use, a fluid sample may flow into the tube 80 at the first end 82 and out of the tube 80 at the second end 84. Alternatively, the fluid sample may flow through the tube 80 in the opposite direction. In use, a sample fluid flows through the quartz tube 80 and experiences UV light from the UV lamp 76, as the sample fluid flows through the coil. The UV light passes though the coil, strikes the UV reflector(s) and reflects back though the coil again. A volume of approximately 300μ1 may be subjected to UV light at any one time. The arrangement of the coil around the UV lamp, with the coil being substantially surrounded by the UV reflector(s) may advantageously increase the exposure of the fluid to the UV light. The length of time that the fluid is exposed to the UV light may be increased, since the fluid follows a relatively long, tortuous path as it passes through the coil. Furthermore, fluid in the tube may be exposed to UV light emitted from the UV lamp before and after the UV light is reflected by the UV reflector(s). Accordingly, for a UV light source having a given power output, the exposure of the fluid to the UV light may be increased. Thus, for example, a relatively low power UV light source may be employed to achieve the desired degradation of the at least one chemical species in the fluid. Employing a relatively low power UV light source may be advantageous for a device that is intended to be used in situ in a remote location for an extended period of time. Additionally or alternatively, the device may be capable of being operated at a relatively higher flow rate, thereby more quickly preparing fluid samples for chemical analysis. The same functional effects may be achieved with other arrangements of the ultraviolet light source, tube and ultraviolet reflector(s). For instance, the portion(s) of the tube located between the ultraviolet light source and the ultraviolet reflector(s) may provide a suitably long and/or tortuous fluid flow path without having the form of a coil.

Many other modifications will be apparent to the person skilled in the art without departing from the scope of the invention. For instance, the tube may be made from sapphire glass.

A device according to the invention may be a component of a system, in which the device is connected to a chemical sensor and/or analyser. The chemical sensor and/or analyser may be in fluid communication with, and located downstream of, the device.

Claims

1. A device suitable for preparing fluid samples for chemical analysis, the device comprising:

an ultraviolet light source;

2. The device according to claim 1 , wherein the ultraviolet transmitter and the ultraviolet reflector together define the fluid path.

3. The device according to claim 2, wherein the ultraviolet reflector has a channel therein and the UV transmitter fluidically seals the channel.

4. The device according to claim 3, wherein the channel is helical , linear or serpentine.

5. The device according to any one of claims 2 to 4, wherein (i) the ultraviolet reflector is tubular and the ultraviolet transmitter is tubular or (ii) the ultraviolet reflector is planar and the ultraviolet transmitter is planar.

6. The device according to claim 1 , wherein the ultraviolet transmitter is a tube that defines the fluid path therein.

7. The device according to claim 6, wherein the tube is straight at least in part and/or serpentine at least in part.

8. The device according to claim 7, wherein the tube comprises (i) a coiled portion arranged around the ultraviolet light source or (ii) a series of linear tubes arranged around the ultraviolet light source.

9. The device according to any one of the preceding claims, wherein the UV reflector comprises or consists of polytetrafluoroethylene, which is optionally mirrored.

10. The device according to any one of the preceding claims, wherein the UV reflector comprises a polished metal, a polished metal oxide or a polished metal nitride.

1 1. The device according to any one of the preceding claims, wherein the UV transmitter does not comprise silicon.

12. The device of claim 1 1 , wherein the UV transmitter comprises sapphire.

13. The device according to any one of claims 1 to 10, wherein the UV transmitter comprises silicon.

14. The device according to claim 13, wherein the UV transmitter comprises quartz, optionally coated with a non-silicon containing material.

15. The device according to any one of the preceding claims comprising (i) more than one ultraviolet reflector and/or (ii) more than one ultraviolet transmitter .

16. The device according to any one of the preceding claims, wherein the ultraviolet reflector(s) substantially surround the UV light source.

17. The device according to any one of claims 1 to 15, wherein the UV transmitter(s) substantially surround the ultraviolet reflector(s).

18. The device according to any one of the preceding claims, wherein the device is configured to be connectable to a chemical sensor and/or analyser.

19. The device according to any one of the preceding claims, wherein the ultraviolet light source comprises (i) a low pressure ultraviolet light source and / or (ii) a light emitting diode.

20. The device according to any one of the preceding claims, wherein the ultraviolet light source has an output at a UV wavelength of no more than lOOmW/cm² as measured at ¾ inches from the light source.

21. The device according to any one of the preceding claims, wherein the ultraviolet light source has an output of no more than lOOmW.

22. The device according to any one of the preceding claims, additionally comprising restraining means to prevent thermal expansion of the UV reflector.

23. The device according to any one of the preceding claims , wherein the UV transmitter forms, at least in part, a pressure housing.

24. The device according to any of the preceding claims additionally comprising one or more lenses to focus the UV light onto the fluid path.

25. The device according to any of the preceding claims additionally comprising a heat sink to dissipate heat away from the UV light source.

26. A casing containing the device according to any of the preceding claims in which the casing is capable of withstanding high pressure.

27. A process for preparing a fluid sample for chemical analysis, the process comprising:

providing a fluid comprising an analyte chemical species; and

passing the fluid along the fluid path of the device according to any one of claims 1 to 25 such that the emitted and reflected ultraviolet light cause degradation of at least one of the analyte chemical species.

28. The process according to claim 27, wherein the fluid is water, seawater or an aqueous solution.

29. The process according to claim 27 or claim 28, wherein the fluid comprises polyvinylpyrrolidone.

30. The process according to any one of claims 27 to 29, wherein the analyte chemical species comprise organic compounds.

31. The process according to any one of claims 27 to 30, wherein the analyte chemical species comprise (i) phosphorus compounds, preferably organophosphorus compounds; (ii) nitrogen compounds, preferably organonitrogen compounds ; and/or organically-bound metal, preferably arsenic .

32. The process according to any one of claims 27 to 31 , wherein the process additionally comprises subjecting the fluid sample to subsequent chemical analysis.

33. A system comprising at least one device according to any one of claims 1 to 25 and a chemical sensor and/or analyser, wherein the chemical sensor and/or analyser is disposed downstream of, and in fluid communication with, the device(s).

34. The system according to claim 33, wherein the chemical sensor and/or analyser comprises a microfiuidic sensor and/or analyser.

35. The system according to claim 33 or claim 34, wherein the chemical sensor and/or analyser is a component of a lab -on-chip device.