EP0606374A1 - Titrage rapide de l'or et instrument connexe - Google Patents

Titrage rapide de l'or et instrument connexe

Info

Publication number
EP0606374A1
EP0606374A1 EP92921528A EP92921528A EP0606374A1 EP 0606374 A1 EP0606374 A1 EP 0606374A1 EP 92921528 A EP92921528 A EP 92921528A EP 92921528 A EP92921528 A EP 92921528A EP 0606374 A1 EP0606374 A1 EP 0606374A1
Authority
EP
European Patent Office
Prior art keywords
radiant energy
gold
concentration
sample solution
wavelengths
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP92921528A
Other languages
German (de)
English (en)
Inventor
Herbert L. Berman
Georges P. Derbalian
Huey-Rong Christina Jaw
John Junes Lee
Myron A. Beigler
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BIOMYNE TECHNOLOGY Co
Original Assignee
BIOMYNE TECHNOLOGY Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by BIOMYNE TECHNOLOGY Co filed Critical BIOMYNE TECHNOLOGY Co
Publication of EP0606374A1 publication Critical patent/EP0606374A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
    • G01N21/64—Fluorescence; Phosphorescence
    • G01N21/6428—Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes"
    • G01N21/643—Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes" non-biological material
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/24—Earth materials
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J1/00—Photometry, e.g. photographic exposure meter
    • G01J1/10—Photometry, e.g. photographic exposure meter by comparison with reference light or electric value provisionally void
    • G01J1/16—Photometry, e.g. photographic exposure meter by comparison with reference light or electric value provisionally void using electric radiation detectors
    • G01J1/1626—Arrangements with two photodetectors, the signals of which are compared
    • G01J2001/1636—Arrangements with two photodetectors, the signals of which are compared one detector directly monitoring the source, e.g. also impulse time controlling
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
    • G01N21/64—Fluorescence; Phosphorescence
    • G01N2021/6491—Measuring fluorescence and transmission; Correcting inner filter effect
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
    • G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
    • G01N2021/7769—Measurement method of reaction-produced change in sensor
    • G01N2021/7786—Fluorescence
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/02—Mechanical
    • G01N2201/025—Mechanical control of operations
    • G01N2201/0256—Sensor for insertion of sample, cuvette, test strip

Definitions

  • the present invention relates to analytical methods.
  • the present invention relates to methods and apparatus useful for performing a rapid assay of gold or other elemental concentrations, especially low concentrations of gold in rock and soil samples.
  • the present invention relates to analytical methods and apparatus that are both rapid and portable, so as to be useful in field applications.
  • Fire assay laboratories are large, labor-intensive facilities which consume large quantities of power and water, and frequently emit hazardous lead fumes.
  • Another drawback to the fire assay method of analysis is the fact that cross contamination can readily occur between samples.
  • neutron activation the only commercially viable modern analytical technique for the analysis of gold is neutron activation.
  • the requirement for access to a nuclear research reactor makes neutron activation even less readily available than fire assaying.
  • neutron activation inherently requires an eight day "cool down" period for short-lived radioisotopes to decay before counting the gold.
  • an assay method is provided which is capable of measuring gold concentrations over a broad range (i.e., from a few parts per billion up to approximately 30 thousand parts per billion or higher).
  • the invention assay method comprises solubilizing the gold content of the sample, if necessary, then generating a photo-responsive complex with the gold, e.g., a Rhodamine B-gold complex.
  • the gold concentration in the sample is then determined by analysis of the gold complex using optical means.
  • a portable fluorometer instrumentation apparatus that performs a rapid analysis of rocks, soil and other samples to determine the concentration of gold therein.
  • the apparatus is easily transportable to those locations where the rock or soil samples are found.
  • the instrumentation apparatus is easy to operate, and provides an accurate indication of the gold concentration within the samples in a relatively short time, e.g., in less than about three hours.
  • the instrumentation apparatus is capable of measuring gold concentrations over a broad range from a few parts per billion (ppb) to approximately 30 thousand ppb.
  • a system for determining the concentration of gold in a field sample such as a rock or soil sample.
  • One embodiment of the present invention may thus be characterized as a method for determining the concentration of gold in solutions containing the same.
  • Such method comprises carrying out the following steps: (a) contacting the gold- containing solution with: (i) an oxidizing agent, and (ii) at least one crown ether polymer; wherein the contacting is carried out in acidic media under conditions suitable to convert substantially all of the gold ions in solution into their highest oxidation state, and for a time sufficient to allow capture of substantially all of the gold ions in the solution by the crown ether polymer; (b) separating the gold-crown ether complex from the remaining components of the solution; (c) recovering the gold ions from the gold-crown ether complex; (d) contacting the metal-containing solution prepared as described in step (c) with label means, wherein the label means is capable of binding to the gold in its highest oxidation state, and wherein the label means is capable of ready analysis; wherein the contacting is carried out in acidic media under conditions sufficient to allow substantially all of the
  • the invention may be further characterized as a method for determining the concentration of gold in a matrix.
  • Such method comprises the steps: (a) contacting the matrix with an aqueous cyanide- containing solution in the presence of an oxidizer in alkaline condition; (b) contacting the solution obtained from step (a) with: (i) hydrochloric acid in the presence of an oxidizing agent, and (ii) at least one crown ether polymer; wherein the contacting is carried out under conditions suitable to convert substantially all of the gold ions in solution into their highest oxidation state, and for a time sufficient to allow capture of substantially all of the gold ions in the solution by the crown ether; (c) separating the gold-crown ether complex from the remaining components of the solution; (d) recovering the gold ions from the gold-crown ether complex; (e) contacting the gold-containing solution prepared as described in step (d) with label means, wherein the label means is capable of binding to the gold in their highest oxidation state
  • a further embodiment of the invention may be characterized as instrumentation apparatus useful in the practice of the present invention.
  • instrumentation apparatus includes: (a) means for generating radiant energy within a first narrow band of wavelengths; (b) coupling means for coupling the radiant energy to a prepared sample under investigation; and (c) detection means radiantly coupled to the sample for detecting any transmissive light that passes through the sample and falls within the first narrow band of wavelengths, or any fluoresced light emitted from the sample that falls within a second narrow band of wavelengths.
  • the presence of the transmissive or fluoresced light within the first or second narrow band of wavelengths, respectively, indicates the presence of a particular element, e.g. gold, within the sample.
  • the intensity or magnitude of the detected transmissive or fluoresced light provides a measure of the concentration of the particular element within the sample.
  • a conversion chart or table is generated, e.g., by measuring samples containing known concentrations of the particular element, that allows for the direct conversion of the measured fluoresced light to a concentration value of the element within the sample.
  • a fiber optic bundle is used to couple radiation energy to and from the sample under test avoids the problem of "inner filter effect" commonly found in prior art fluorometer devices.
  • the inner filter effect when present, produces ambiguous results in the signal output from the detector.
  • Yet another embodiment of the invention may be characterized as an analysis system for determining the concentration of gold in a field sample.
  • Such system includes: (a) binding means for binding a portion of the field sample to a suitable label means, such as Rhodamine B, thereby producing a radiation complex of the label means plus gold; (b) irradiating means for irradiating the label means to which the sample is bound with radiation energy falling within a first narrow band of wavelengths, this irradiating means including fiber optic means for directing radiation to and collecting radiation emitted from the sample complex; and (c) detecting means coupled to the fiber optic means for detecting radiation emitted from the sample within a second narrow band of wavelengths.
  • a suitable label means such as Rhodamine B
  • the metal-label means complex emits radiation energy within the second narrow band of wavelengths in response to irradiation with radiation energy within the first narrow band of wavelengths only when the field sample bound to the label means contains the particular metal being assayed. Further, because the amount or intensity of the radiation thus emitted is proportional to the amount of metal bound to the label means, the magnitude of the detected radiation provides a simple and quick measure of the metal concentration within the field sample. Additional enhancements of the system optionally include processing means for automatically converting the detected radiation within the specified band to a measure of the gold concentration within the field sample.
  • the sample complex comprises a suitable ligand to which a portion of a soil or rock sample believed to contain gold has been bound.
  • An advantageous feature of such instrumentation apparatus is that fluorescence and transmissive readings may be obtained over a wide dynamic range.
  • a related feature provides good proportionality between the fluorescence/ transmissive readings and the gold concentrations.
  • Other features of such apparatus include an overall accuracy of ⁇ 15%.
  • It is still another feature of the invention to combine process methodology with a novel fluorometer/transmissive instrumentation apparatus comprising a particular selection of chemicals, treatment conditions, instruments, circuits and shielding configuration that effectively eliminates the effects of extraneous signals and background radiation, thereby permitting noise repression and the reading of very small signals.
  • FIG. 1 is a block diagram illustrating the basic operation of a first embodiment of a fluorometer instrumentation apparatus made in accordance with the present invention
  • FIG. 2 is a more detailed block diagram of the first embodiment of the fluorometer instrumentation apparatus of the present invention as generally illustrated in HG. 1;
  • FIG. 3 is a graph illustrating the transmissivity of the two filters used within the apparatus of FIG. 2;
  • FIG. 4 is a representative calibration graph used with or by the apparatus of FIG. 2 in order to convert the measured intensity of the fluoresced light to a measure of gold concentration
  • FIG. 5 is a top view block diagram illustrating the basic operation of a combined fluorometer/transmissive instrumentation apparatus made in accordance with the preferred embodiment of the present invention
  • FIG. 6 is a more detailed top view block diagram of the combined fluorometer/transmissive instrumentation apparatus of the preferred embodiment as generally illustrated in FIG. 5;
  • FIG. 7A and 7B are a flow diagram showing the steps taken when utilizing the preferred embodiment, as shown in FIG. 6, to measure gold concentration in a sample.
  • Like components or elements are referred to with like reference numerals throughout the various views of the drawings.
  • the present invention provides a method, and instrumentation apparatus for rapidly carrying out the method, for determining the concentration of a specific element, e.g., gold, in a material (field sample).
  • the method and instrumentation apparatus have been summarized above.
  • the invention method can be carried out in both batch and continuous modes.
  • the material to be analyzed is in particulate form such as an ore, rock, or the like
  • the ore powder is then roasted under an oxidizing atmosphere in the temperature range of 500-800 °C for up to one hour to remove volatile elements, thereby minimizing the likelihood of false positives.
  • the finely ground particulate is suspended in an aqueous cyanide-containing solution in the presence of an oxidizer e.g. calcium peroxide, sodium peroxide, potassium permaganate, bromine, chlorine and hydrogen peroxide.
  • an oxidizer e.g. calcium peroxide, sodium peroxide, potassium permaganate, bromine, chlorine and hydrogen peroxide.
  • Cyanide compounds contemplated for use in this solubilization step include sodium cyanide, potassium cyanide, and the like. Potassium cyanide is presently preferred.
  • the quantity of cyanide employed can vary widely, so as to provide a final cyanide concentration in the metal-containing aqueous solution which typically falls in the range of about 0.001 M - 0.5 M. Currently, final cyanide concentrations in the range of about 0.1 M are employed.
  • a base e.g., potassium hydroxide, is added to the cyanide solution.
  • a key element of this invention is the discovery that the crown ether polymer available from all commercial sources must be pretreated in order to obtain consistent recovery of the gold complex, especially when the sample gold concentration is below about 1000 ppb.
  • the variation in gold recovery percentage is caused by adsorption sites of other than the gold complex dimension that would trap Au complex molecules but not release them at a later stage.
  • the pretreatment invention requires filling the crown ether polymer with some metal species (e.g. , Ga, As, Fe, Au) that fill the adsorption sites, and then extracting most of the metal species out of the cavities leaving the "bad sites" that are filled. This treatment gives about 40% improvement in consistency of recovering gold complex concentration in the range of 100 ppb.
  • crown ether polymer capable of complexing with the metal to be assayed is contemplated for use in the practice of the present invention.
  • exemplary crown ether polymers include poly(dibenzo-18-crown-6) [poly(DB18C6)], and the like.
  • the amount of crown ether polymer employed is in the range of about 20-100 mg/ml of metal-containing solution.
  • the crown ether polymer bound-metal material is then separated from the remaining components of the solution.
  • This separation can readily be carried out by removal of the liquid from the particulate material using standard techniques such as decantation, filtration, aspiration or the like. It is preferred, to insure removal of substantially all extraneous species, to then wash the particulate material with 0.6 M HCI. It is preferred that the crown ether polymer separation be used in the column form. This is because the time to perform the separation is reduced dramatically when the column form is used from what would be required if other separation techniques, e.g., tumbling, were employed. For example, the crown ether separation may take 2V_ hours when tumbling is used, but may only require 30 minutes when the column form is used.
  • the gold ions are recovered from the complex. This is done, for example, by extracting the ions from the complex with a polar oxygen-containing organic solvent such as alcohol, ketone, etc. Acetone (a ketone) is preferred.
  • label means refers to a chemical species which is capable of binding to AuCV, and which is also capable of ready analysis.
  • exemplary label means include chromophores, metal-complexing agents which are capable of fluorescing when excited with incident light of proper wavelength, and the like.
  • Exemplary label means include I_ ⁇ c amine B (i.e., N-(9-(2- carboxyphenyl)-6-(diethylamine)-3H-xanthen-3-ylidene)-N-ethyl ethanaminium chloride; also known as tetraethyl rhodamine), Brilliant Green,
  • Rhodamine B is the presently preferred label means because it gives very low levels of background fluorescence when gold concentrations are determined.
  • Substantial binding between AuCV and the dye is obtained by vortexing the mixture for a few seconds at room temperature. Following such treatment, it is desirable to separate substantially all unbound label means from the sample so as to reduce background noise in the invention analytical method. Such removal can be carried out, for example, by extraction of the label means-metal complex with an organic solvent (e.g. C ⁇ H ⁇ , ether, preferably diisopropyl ether) from the aqueous media in which the complex is generated.
  • an organic solvent e.g. C ⁇ H ⁇ , ether, preferably diisopropyl ether
  • a sample thus prepared is ready for analysis of the gold content therein.
  • Metal analysis in accordance with the present invention is accomplished by determining the amount of label means incorporated by the sample. Where the label means is capable of emitting fluorescent radiation upon excitation, analysis can be accomplished by exciting the label means at a specified wavelength, then measuring the intensity of the emissions at a specified wavelength different from the wavelength used for excitation.
  • Various means for carrying out such analysis employs novel instrumentation apparatus described hereinbelow.
  • a first embodiment of the apparatus of the present invention facilitates the practice of the above-described assay method by providing portable fluorometer instrumentation apparatus that allows the assay method to be quickly carried out . in the field at or near the location of the soil or rock samples being assayed for the presence of gold.
  • a block diagram illustrating the basic components of fluorometer apparatus 10 made in accordance with the invention is shown in FIG. 1. These basic components include a source of radiant energy 14, a dichroic mirror 16, a fiber optic bundle 18, and a detector 20.
  • a second detector 15 may also be employed.
  • the dichroic mirror 16 is positioned so as to direct radiant energy generated by the source 14 into the fiber optic bundle 18.
  • the detector 20 is positioned relative to the dichroic mirror 16 so as to receive radiant energy emitted from the fiber optic bundle 18.
  • the detector 15 is positioned to receive radiant energy generated by the source in order to detect variations in the intensity thereof that occur over time. Such variations, if not corrected, could introduce an error in the measurements made by the apparatus.
  • a sample complex 12 comprising a suitable label means, such as Rhodamine B, to which a desired element, such as gold (when present) has been bound, is prepared as described above in connection with the method of the present invention.
  • the gold-Rhodamine B complex fluoresces in the spectral region of 560 to 580 nanometers (nm) when excited by radiant energy (light) in the spectral region of 540 to 550 nm.
  • gold-containing complex 12 is a gold-PQPP complex
  • exaltation in the range of about 300 nm leads to fluorescence in the spectral region of about 460 nm.
  • the amount of emitted fluorescence is a monotonically increasing function of the gold concentration in the complex.
  • the fluorometer instrumentation apparatus 10 operates as follows:
  • the source of radiant energy 14 generates radiation of a first wavelength ⁇ where ⁇ , for the gold- Rhodamine B complex falls within the range of 540 to 550 nm (about 300 nm for gold-PQPP).
  • This radiation is directed into the fiber optic bundle 18 using the dichroic mirror 16, and is also directed into the detector 15.
  • the sample complex in response to the ⁇ , radiation, fluoresces radiation of a second wavelength ⁇ , where ⁇ 2 (for the gold-Rhodamine B complex) falls within the range of 560 to 580 nm (about 460 nm for gold-PQPP complex).
  • the ⁇ 2 radiation is directed from the sample complex 12 through the fiber optic bundle 18, through the dichroic mirror 16 and to the detector 20.
  • the detector 20 is configured to detect the amount of radiation of wavelength ⁇ 2 . This detection thus provides a direct measure of the gold concentration within the sample complex 12.
  • the output intensity of the source 14 will vary to some degree during the measurement of a group of references and samples.
  • the detector 15 allows the source intensity to be monitored so that appropriate corrections in the determination of the gold concentration can be made, as described below.
  • Fiber optic bundles are widely available, and can be constructed of a variety of materials, including silica, glass, polymethyl methacrylate, polycarbonate, polystyrene, and the like. Commercially available fiber optic bundles can be used as received, without the need for any special treatment and/or preparation prior to use. Typically, the only modification made is to remove the cladding from the bundle from that part of the bundle which will be directly exposed to sample.
  • FIG. 2 a more detailed block diagram of one embodiment of fluorometer instrumentation apparatus made in accordance with the present invention is shown. (It is noted that like numerals are used to represent like parts in FIG. 2 and FIG. 1). As seen in FIG. 2, the apparatus includes the same basic components shown in FIG.
  • the fiber optic bundle 18 directs radiation to and from the sample complex 12 under test.
  • the source of radiant energy 14 comprises a power supply 22 coupled to a broad band light source 24.
  • the light generated by the broad band light source 24 is directed through a suitable optical system 27 to a filter 30.
  • the optical system 27 includes any suitable means for efficiently coupling the radiant energy from the broad band light source 24 to the filter 30.
  • the filter 30 is a narrow band filter and filters out all of energy except that of the desired wavelength ⁇ t. (It is to be understood that X, may comprise a narrow band of wavelengths as well as a single wavelength, depending upon the bandwidth of the filter 30.)
  • the optical system 27 includes a fiber optic coupler 26 having one end optically coupled to the light source 24 and the other end at the focal point of a lens 28. Radiant energy from the light source 24 is thus directed through the fiber optic coupler 26 to the lens, where it is directed to the filter
  • ⁇ a narrow band of radiant energy remains, e.g, of wavelength ⁇ ,.
  • the ⁇ , radiant energy is optically reflected from the dichroic mirror 16 to an additional lens 32 so as to be directed or focused into the fiber optic bundle 18.
  • fluoresced light from the complex sample 12 is emitted from the fiber optic bundle 18 and is focused through the lens 32 back to the dichroic mirror 16. This fluoresced light passes through the mirror 16 to the detector 20.
  • the detector 20 includes a narrow band filter 34 configured to pass only radiation having a wavelength ⁇ 2 . (It is to be understood that ⁇ 2 may comprise a narrow band of wavelengths, as well as a single wavelength.) That is, radiation or light of wavelengths other than ⁇ 2 is significantly attenuated by the filter 34. Hence, if the radiation fluoresced from the complex sample 12 includes the desired element, e.g., gold, it will fall within the wavelength band ⁇ 2 , and such radiation will pass through the filter 34.
  • the desired element e.g., gold
  • the radiation After passing through the narrow band filter 34, the radiation is directed or focused through a second lens 36 to a photodetector 38.
  • the photodetector 38 operates in conventional manner and detects the amount of radiation incident thereon. Thus, any radiation of wavelength ⁇ 2 that makes its way through the filter 34 is detected by the photodetector 38. In response to such detection, the photodetector 38 generates an electrical signal. The amplitude of this signal is proportional to the intensity of the detected radiation.
  • the electrical signal generated by the photodetector is amplified by amplifier 40. The output signal of the amplifier 40 may then be monitored to determine how much, if any, radiation or light of wavelength ⁇ 2 was detected by the photodetector 38.
  • a large output signal indicates ⁇ 2 radiation of a high intensity, which in turn indicates a high concentration of the particular element within the complex sample (assuming a uniform volume of the sample).
  • a small output signal indicates ⁇ 2 radiation of a low intensity, which in turn indicates a low concentration of the particular element within a uniform volume of the sample complex.
  • the output signal from the amplifier 40 may be calibrated to provide a direct measure (indicated, e.g., in parts per billion, or ppb) of the concentration of the element within the sample complex.
  • the output signal from the amplifier 40 is measured with a digital voltmeter (DVM) 42. Further, as desired, this output voltage may be recorded and/or stored in a data logger 44, or equivalent device. Moreover, for some applications, it may be desirable to couple a suitable processor 46, such as a portable personal computer (PC), to the output voltage of the amplifier 40.
  • DVM digital voltmeter
  • PC portable personal computer
  • Such coupling may be accomplished directly from the output signal of the amplifier 40 if the processor 46 includes internal analog-to-digital (A/D) conversion means (for converting the analog output signal from the amplifier 40 to a digital signal suitable for use with the PC); or, alternatively, if the DVM 42 includes a digital output port, as many commercially available DVM's do, the coupling may be made from the DVM 42 to the processor 46.
  • A/D analog-to-digital
  • the processor 46 when used, performs various processing functions associated with the amplifier output signal.
  • the processor may include a "look-up table" or equivalent (e.g., an equation) that is stored therein that allows the measured output voltage of the amplifier 40 to be converted directly to a concentration value of the desired element.
  • the processor may include various digital processing steps that analyze the output voltage data obtained from the amplifier 40 over a specified period of time in order to further enhance such data, e.g., by removing noise therefrom using conventional digital filtering techniques.
  • the detector 15 is positioned to sense the incident radiation of wavelength ⁇ , generated by the source 14. Such radiation is directed through a suitable lens 29 to a photodetector 39.
  • the photodetector 39 operates in conventional manner and detects the amount of radiation incident thereon. Thus, any radiation of wavelength ⁇ , from the source 14 that makes its way through the filter 30 is detected by the photodetector 39. Additional filters, positioned in front of the lens 29, for filtering out all radiation except that of wavelength ⁇ j may also be used, as required. In response to detection of the ⁇ t radiation, the photodetector 39 generates an electrical signal. The amplitude of this signal is proportional to the intensity of the detected radiation. The electrical signal generated by the photodetector is amplified by amplifier 41. The output signal of the amplifier 41 is then monitored to determine how much radiation or light of wavelength was detected by the photodetector 39. A large output signal indicates ⁇ j radiation of a high intensity. Similarly, a small output signal indicates ⁇ , radiation of a low intensity.
  • the output signal from the amplifier 41 is measured with a digital voltmeter (DVM) 43. Further, if desired, this output voltage may be recorded and/or stored in a data logger 45, or equivalent device. Moreover, for most applications, it is adequate to couple the output of the amplifier 41 directly to the processor 46, such as a portable personal computer (PC). Such output signal may then be used to provide a reference signal that indicates variations that may have occurred in the intensity of the ⁇ i radiation.
  • DVM digital voltmeter
  • the detector 15 thus monitors the intensity of the ⁇ , source.
  • the measured intensity thus represents a reference signal, S Ref .
  • the intensity of the ⁇ 2 fluoresced signal is another signal, S F .
  • the signal S F may be corrected for variations that may have occured in the intensity of the ⁇ , source as follows:
  • Scorr (Sp • S Ref )/S ⁇ l
  • Sc ⁇ - represents the correction of the signal S F
  • S ⁇ represents the current intensity measurement of the source 14 as made by the detector 15.
  • the described correction can be made by the processor for each measurement made.
  • An additional embodiment of the detector 20 may include a plurality of filter-photodetector-amplifier sets, each adapted to sense radiation of a particular wavelength. The output signals from all of such sets may then be monitored, e.g., using the processor 46, to provide an overall assay report of the contents of the sample complex, including an indication of the concentrations of a plurality of elements within the sample complex.
  • a conventional laser may be used, e.g, a He-Ne laser that provides an output wavelength of 543.5 nm.
  • the narrow output of such He-Ne laser may be coupled through any suitable means directly into the fiber optic bundle 18, with a small portion thereof being coupled directly into the detector 15.
  • such coupling will utilize at least the dichroic mirror 16 and the lens 32, thereby allowing the laser to be positioned off axis from the fluoresced radiant energy traveling out from the complex sample 12.
  • FIG. 3 is a graph illustrating the transmission properties through the two filters 30 and 34 used within the apparatus of FIG. 2. These transmission properties are selected for the detection of gold as a gold-Rhodamine B complex. It is to be understood, of course, that similar properties may be selected for the detection of other gold complexes.
  • a first peak or band 70 is centered approximately at 545 nm. This peak or band 70 represents the desired transmission properties of the filter 30 coupled to the broad band energy source 24.
  • a second peak or band 72 is centered approximately at 580 nm. This peak or band 72 thus represents the desired transmission properties of the filter 34 placed prior to the photodetector 38. If a He-Ne laser is used in place of the broad band energy source 24, the wavelength of the He-Ne laser is 543.5 nm, which is roughly centered in the desired peak or band 70.
  • the location of the band 70 and the band 72 would be selected accordingly. For example, if a given complex were to fluoresce radiation having a wavelength of 590 nm in response to being irradiated with radiation having a wavelength of 520 nm, then the first band 70 would be centered at 520 nm, and the second band 72 would be centered at 590 nm.
  • FIG. 4 there is shown a representative calibration graph used with or by the apparatus of FIG. 2 in order to convert the measured intensity of the fluoresced light to a measure of gold concentration.
  • equivalent calibration techniques such as using a look-up table, or an equation, may also be used to convert measured intensity to gold concentration.
  • the graph of FIG. 4, or equivalent table or equation is generated by measuring the fluorescent signal amplitude for a series of samples of uniform volume containing known concentrations of gold. That which is shown in FIG. 4 is only a portion of the overall calibration curve that can be obtained.
  • good calibration data is obtained using the fluorometer apparatus of the invention over a wide dynamic range, e.g., of from 10 ppb to 3,000 ppb.
  • the fluorometer apparatus is able to measure concentration differences on the order of 1 ppb.
  • the accuracy of the combined chemical and optical method from the original samples is approximately ⁇ 15%.
  • the use of the fiber optic bundle 18 avoids a measurement problem, known as the "inner filter effect,” common in spectro- fluorometers of the prior art.
  • This problem results in the amount of emitted fluorescent light reaching a peak level at low metal concentrations, and thereafter decreasing with increasing metal concentration.
  • This "inner filter effect” thus results in a double-valued output and ambiguous readings over the range of metal concentration of interest. See, for example, Yuan et al., “Calculation for Fluorescence Modulation by Absorbing Species and Its Application to Measurements Using Optical Fibers," Analytical Chemistry. Vol. 59, No. 19, 2391-94 (October 1, 1987).
  • the light source 24 may be realized with a Xenon Arc (ILC No. 131), an incandescent lamp, such as the Gilway Technical Lamp No. L7394, or a Helium-Neon laser (No. LSGR-0150M, obtained from Particle Measuring Systems (PMS)). As indicated below, the He-Ne is preferred, but the other sources may also be used.
  • the light source 24 is positioned at the focal point of the lens 28, which may be an aspheric lens No. 06-3097, available from Spindler & Hoyer. Alternatively, the light may be transmitted to the focal point of the lens 28 by the fiber optic bundle 26.
  • the fiber optic bundle 26 may be realized using 1000 micron diameter fibers available from, e.g., Ensign- Bickford.
  • the collimated (focused) beam from the light source 28 is transmitted through the filter 30, which may be obtained from Omega Optical Inc., as Part No. 546BP10.
  • the dichroic mirror 16 may also be obtained from Omega Optical Inc. as Part No. 440 DES P.
  • the lens 32 focuses the light onto the end of the fiber optic bundle 18. This lens 32 may be realized with an aspheric lens, No. 06-3097, obtained from Spindler & Hoyer.
  • the fiber optic bundle 18 is preferably comprised of 1000 micron diameter fibers obtained from, e.g., Ensign-Bickford.
  • the filter 34 through which the fluoresced light is directed, may further be obtained from Omega Optical Inc as Part No. 577BP10.
  • the lens 36 may be the same as the lens 32.
  • the photodetector 38 may be any suitable photodetector, such as a photodiode detector, of which numerous types are commercially available, e.g., a silicon photodiode No S2386, manufactured by Hamamatsu.
  • the electrical signal from the photodiode detector is amplified by the amplifier 40.
  • a low noise, low drift operational amplifier is preferable for this purpose.
  • a Burr-Brown No. OPA128LM amplifier is well suited for this purpose.
  • the amplified output from the amplifier 40 is preferably printed and stored using the data logger 44, which data logger may be obtained from Omega Engineering Inc as Part No. OM-550.
  • the DVM 42 may be obtained from any suitable manufacturer.
  • the components of the detector 15 may be the same as corresponding components of the detector 20. The particular selection of components described above in connection with HG. 2 advantageously permits the reading of exceptionally low values of fluoresced light by repressing noise.
  • the preferred amplifier 40 for example, (Burr- Brown No.
  • OPA128LM has ultra-low bias current, very high signal-to-noise ratio and common-mode rejection, and thus allows extremely small signals (electrical currents) to be received from the photodetector 38, which small signals correspond to small sample values.
  • the amplifier 40 converts such small signals to a relatively large output voltage.
  • the preferred filters 30 and 34, the photodetector 38, the lenses 28 and 36, as well as the He-Ne laser (if used), as identified above, are all selected with these considerations in mind.
  • the photodetector 38 may respond to very low power incident radiation levels from test samples having extremely low amounts of the metal of interest. For this reason, the use of a He-Ne laser as the radiation source 14 is preferred over the use of a broad-band source, as shown in HG. 2.
  • the fluorometer apparatus of the present invention further utilizes appropriate shielding in the packaging of the components.
  • shielding is necessary to avoid radiative and electrical interference, e.g., background radiation, and is especially needed in packaging the photodetector 38 and the amplifier 40.
  • Such shielding thus includes a special enclosure 39 in which the photodetector 38, the operational amplifier 40, and related components (e.g., a source of electrical power for these components) are housed.
  • the enclosure 39 may be made from any suitable metal, such as copper or aluminum, that prevents low level radiation from passing therethrough and that is a good electrical conductor.
  • the size of the fiber optic bundle 18 should be selected for maximum delivery of the ⁇ , and ⁇ 2 signals with minimum noise. In the preferred embodiment, this requirement is met by utilizing fiber bundles having a diameter of about 1000 microns.
  • all of the components of the apparatus 10 are sufficiently small and lightweight so that they may be easily transported, e.g., in a trailer, truck, van, by backpack, or the like, thereby allowing the entire apparatus to be portable and easily transported to a field location where soil or rock samples are to be assayed.
  • a second embodiment of the apparatus of the present invention facilitates the practice of the above-mentioned assay method by providing a combined portable fluorometer/transmissive instrumentation apparatus that, like the first embodiment, allows the assay method to be quickly carried out in the field or near the location of the soil or rock samples being assayed for the presence of gold.
  • the second embodiment further improves upon the first embodiment by providing a fluorometer/transmissive instrumentation apparatus that detects a wide range of gold concentrations (e.g., from a few parts per billion (ppb) to about thirty-thousand ppb) without the use of a fiber-optic bundle.
  • a fluorometer/transmissive instrumentation apparatus that detects a wide range of gold concentrations (e.g., from a few parts per billion (ppb) to about thirty-thousand ppb) without the use of a fiber-optic bundle.
  • FIG. 5 A block diagram of a combined fluorometer/transmissive instrumentation apparatus 11, made in accordance with the second embodiment of the invention is shown in HG. 5.
  • the apparatus 11 includes a source of radiant energy 14, a source detector 15, a florescence detector 20, and a transmission detector 21.
  • the florescence detector 20 is positioned relative to the sample 12 so as to receive radiant energy fluoresced from the source 14 by the sample 12.
  • the source detector 15 is positioned relative to a suitable dichroic mirror 17 so as to receive a small portion of the radiation emitted by the source 14.
  • the transmission detector is positioned relative to the source 14 so as to receive radiant energy transmitted through the sample 12.
  • a sample complex 12 comprising a suitable label means to which gold (when present) has been bound, is prepared as described above in connection with the method of the present invention.
  • the gold-complex fluoresces in the spectral range at about 577 nm and transmits radiant energy at 543.4 nm in response to a radiant energy source that emits radiation at 543.5 nm.
  • the intensity of the fluoresced radiant energy is a monotonically increasing function of the gold concentration in the complex whereas at higher gold concentrations (e.g., above 2000 ppb), the intensity of the transmitted radiant energy is a monotonically decreasing function of the gold concentration in the complex.
  • the combined fluorometer/transmissive instrumentation apparatus 11 operates as follows:
  • the source of radiant energy 14 generates radiation of a first wavelength ⁇ , where ⁇ i for the gold-Rhodamine B complex is about 543.5 nm. This radiation is directed into the sample 12.
  • the sample complex in response to the ⁇ , radiation, fluoresces radiation of a second wavelength ⁇ 2 , where ⁇ 2 for the gold-Rhodamine complex is about 577 nm.
  • the ⁇ 2 radiation is detected by the detector 20.
  • the detector 20 is configured to detect the amount of radiation of wavelength ⁇ 2 .
  • the sample complex transmits the ⁇ ! radiation.
  • the transmitted radiation has been designated ⁇ ,' in FIG.
  • the ⁇ ,' radiation is detected by the detector 21.
  • the ⁇ i radiation is detected by the detector 15.
  • the detector 21 is configured to detect the amount of radiation of wavelength ⁇ , ⁇
  • the combined detections of ⁇ 2 and ⁇ ,' thus provide a direct measure of the gold concentration within the sample complex 12.
  • the detection of the incident radiation by the detector 15 allows a suitable correction to be made to the measurments made by the detectors 20 and 21 so as to correct for variations in the intensity of the source 14.
  • FIG. 6 a more detailed block diagram of the second embodiment of the combined fluorometer/transmissive instrumentation apparatus 11 is shown.
  • the apparatus includes the basic components shown in HG. 5, i.e., a source of radiant energy 14, a calibration detector 15, a fluorescence detector 20, and a transmission detector 21.
  • the source of radiant energy 14 comprises a power supply 22 coupled to a narrow band laser light source 25. Incident light generated by the laser 25 is directed through an electro stop or solenoid-controlled shutter 29.
  • the electro shutter 29 is controlled by a solenoid 23 to be either open or closed. Operation of the solenoid in response to a programmed personal computer (PC) or equivalent processor 46, or other control means, is explained more fully below with respect to HGS. 7A and 7B.
  • PC personal computer
  • ND neutral density
  • the neutral density filter 31 reduces the intensity of the light generated by the laser 25 to an appropriate level,; and the aperture 33 is used to confine the light beam to the sample 12.
  • the fluoresced light or radiation from the sample complex 12, generated in response to the incident light passes to the fluorescence detector 20.
  • the detector 20 includes a light shield 13 with a narrow slit 19 as described above in connection with HG. 5.
  • the detector 20 further includes a first fluorescence band filter 35 configured to pass only radiation having a wavelength ⁇ 2 .
  • ⁇ 2 is 577 nm. That is, radiation or light of wavelengths other than ⁇ 2 is significantly attenuated by the filter 35.
  • the sample includes the desired element, e.g. gold, the radiation fluoresced from the complex sample 12 will fall within the wavelength band ⁇ 2 , and such radiation will pass through the filter 35.
  • the radiation After passing through the first band filter 35, the radiation passes through a second fluorescence band filter 37.
  • the second fluorescence band filter 37 is also configured to pass only radiation having wavelength ⁇ 2 .
  • the second fluorescence band filter functions in a manner similar to the first fluorescence band filter so as to further attenuate light of wavelengths other than wavelength ⁇ 2 that passes through the first fluorescence band filter 35.
  • the radiation After passing through the second fluorescence band filter 37, the radiation is directed to a photodetector 38.
  • the photodetector 38 operates in a conventional manner and detects the amount of radiation incident thereon. Thus, any radiation of wavelength ⁇ 2 that makes its way through the first fluorescence band filter 35 and the second fluorescence band filter 37 is detected by the photodetector 38. In response to such detection, photodetector 38 generates an electrical signal wherein the amplitude of the signal is proportional to the intensity of the detected radiation.
  • the electrical signal generated by photodetector 38 is amplified by amplifier 40. The output signal of the amplifier 40 may then be monitored to determine how much, if any, radiation or light of wavelength ⁇ 2 was detected by the photodetector 38.
  • a large output signal indicates ⁇ 2 radiation of high intensity, which in turn indicates a high concentration of the particular element within the complex sample (assuming uniform volume of the sample).
  • a small output signal indicates radiation of low intensity, which in turn indicates a low concentration of the particular element within a uniform volume of the sample complex.
  • the output signal may be calibrated to provide a direct measure (indicated, e.g., in parts per billion, or ppb) of the concentration of the element within the sample complex.
  • the output signal from the amplifier 40 may be measured with a digital voltmeter (DVM) 42. As desired, this output may be recorded or stored in a data logger 44, or equivalent device.
  • DVM digital voltmeter
  • the transmission detector 21 includes an aperture 43 to collimate the transmitted light and direct it to a desired detection location. Further, the aperture helps minimize scattering into the detector from outside sources.
  • Light entering through the aperture 43 is directed through a transmission band filter 45.
  • the filter 45 is configured to pass only radiation having a wavelength of ⁇ i'. In the preferred embodiment, the filter 45 is centered at about 546 nm so as to readily pass transmitted radiation having a frequency of ⁇ , (543.5 nm). That is, radiation or light of wavelengths other than ⁇ i' is significantly attenuated by the filter 45.
  • the radiation fluoresced from the complex sample 12, which has wavelength ⁇ 2 will be significantly attenuated and therefore have minimal effect on the transmission measurements made by the transmission detector 21.
  • the radiation transmitted through the sample 12, which has wavelength ⁇ ,' will pass through the filter 45.
  • the light passing through the filter 45 is directed through an ND filter 47, which ND filter 47 reduces the intensity of the light transmitted therethrough by a controlled amount.
  • the radiation After passing through the ND filter 47, the radiation is directed to a photodetector 48.
  • the photodetector operates in a conventional manner and detects 5 the amount of radiation incident thereon.
  • any radiation of wavelength ⁇ that makes its way through the transmission filter 45 and the ND filter 47 is detected by the photodetector 48.
  • photodetector 48 In response to such detection, photodetector 48 generates an electrical signal wherein the amplitude of the signal is proportional to the intensity of the detected radiation.
  • the electrical signal generated by photodetector 48 is 10 amplified by amplifier 50.
  • the output signal of the amplifier 50 is then monitored to determine how much, if any, radiation or light of wavelength ⁇ ,' is detected by the photodetector 48.
  • a decreasing signal indicates a high concentration of the particular element within the complex sample (assuming uniform volume of the sample). Similarly, a higher output signal indicates a lower concentration of the particular ' 15 element within a uniform volume of the sample complex.
  • the output signal may be calibrated to provide a direct measure (indicated, e.g., in parts per billion, or ppb) of the concentration of the element within the sample complex.
  • the output signal from the amplifier 50 may be measured with a digital voltmeter (DVM) 52. As desired, this output may be recorded 20 or stored in a data logger 44, or equivalent device.
  • DVM digital voltmeter
  • HG. 6 e.g., the photodetectors, amplifiers, DVM's, data loggers, laser source, etc., may be realized using the same types of devices and equipment as described previously in connection with HG. 2. 25
  • a personal computer (PC) 46 or equivalent processor, is coupled to the output of the amplifier 40 and the output of the amplifier 50.
  • Such coupling may be direct if the computer 46 includes internal analog-to-digital (AID) conversion means (for converting the analog output signal from the amplifier 40 and the amplifier 50 to a digital signal suitable for use with the PC 46); or, 30 alternatively, if the DVM's 42 and 52 include a digital output port, as many commercially available DVM's do, the coupling may be made from the DVM's 42 and 52 to the processor 46. Further details associated with the operation of the embodiment shown in Fig. 6 may be found in Applicants' copending U.S. patent application Serial No. 07/769,531, filed October 1, 1991, incorporated herein by reference.
  • the signals received by the processor 46 from the amplifiers 40 and 50 are used to automatically calculate the concentration of the desired element, e.g. gold, present in the complex sample.
  • a calibration graph such as that shown in HG. 4, can be generated (or mathematically expressed) by analyzing complex samples from known desired element concentrations, e.g. known gold concentrations.
  • a first calibration curve is generated based on the fluorescence detector 20 output, and a second calibration curve is generated based on the transmission detector 21 output.
  • calibration curve refers to any means, whether a mathematical equation, or equivalent, that relates one variable, i.e., the detector output, to another variable, i.e., the gold concentration.
  • the first calibration curve is generated, based on known complex sample concentrations, and may be mathematically expressed as:
  • C is the gold concentration
  • S is the fluorescence detector output
  • £ t is the effective length of the cuvette
  • K, and S 0 are constants.
  • (1) to accurately estimate the gold concentration is limited to a lower range of concentrations, e.g., about 0 ppb to 3,000 ppb.
  • the second calibration curve is also derived from known complex sample concentrations, and may be mathematically expressed as:
  • C (Vat j ) x ln (T 0 / T) (2)
  • T is the transmissive detector output
  • l/ ⁇ £ 2 and T 0 are constants.
  • the constants are determined empirically using complex samples containing known concentrations of gold. Representative values of such constants are ⁇ £ 2 ⁇ .0000751; and T 0 ⁇ 1.75 (volts).
  • the ability of Eq. (2) to accurately approximate the second calibration curve is limited to a higher range of concentrations, e.g. 1,000 ppb to 25,000 ppb.
  • the processor 46 calculates a first concentration, based on the fluorescence formula, Eq. (1), and a second concentration, based on the transmission formula, Eq. (2). Because the range of accuracy for the fluorescence formula, equation (1) is limited to approximately 3000 ppb or less, equation (2) is used for concentrations in the range from 2000 ppb to approximately 30,000 ppb. In the overlap range between 2,000 to 3,000 ppb either equation may be used. In this way, this second embodiment provides a significant increase in the dynamic range over the first embodiment.
  • the source detector 15 allows the signals detected by the detectors 39 and 49 to be corrected for variations that occur in the intensity of the incident source 14.
  • the mirror 17 functions as a beam splitter and directs a small portion of the incident radiation (e.g., approximately 4%) to the detector 15.
  • An initial reading of the source intensity is represented as the signal S Ref ;
  • a current reading of the source intensity is represented as a signal S M ;
  • a current reading of the fluoresced radiation is represented as a signal S F ;
  • a current reading of the transmitted radiation is represented as a signal S T .
  • Both the fluorescence and transmission signals S F and S ⁇ may then be corrected by utilizing the following relationships:
  • the transmission properties of the filters 35, 37 and 45 used with the apparatus of HG. 6 are selected for the detection of gold as a gold- Rhodamine B complex in the same manner as used in connection with the filters 30 and 34 associated with the apparatus of FIG. 2.
  • the filter 45 includes a first peak or band centered at approximately 546 nm.
  • the filters 35 and 37 include a second peak or band centered at approximately 577 nm.
  • the laser radiant energy source 25 provides radiant energy of approximate wavelength 543.5 nm, which is roughly centered in the peak or band of the filter 45.
  • FIGS. 7A and 7B a flow diagram is shown that illustrates the manual and programmed steps used to measure the concentration of the desired element within the sample 12 using the fluorometer/transmissive instrumentation apparatus of the second embodiment.
  • Each main step of the method shown in FIGS. 7A and 7B is depicted as a "block". It is submitted that those skilled in the art can readily perform the steps shown in HGS. 7A and 7B (if manual) or write an appropriate program or code for use by the processor 46 (if automatic).
  • block 110 represents the preparation, as described above in connection with the method of the present invention, of the sample complex 12, including contacting the prepared material with a suitable label means to which gold, when present, has been bound.
  • a suitable label means to which gold, when present, has been bound.
  • the solution is transferred into a cuvette, or transparent container, through which the sample solution can be irradiated. Further, during the reading of hte initial reference sample, a measurement is made of the intensity of the radiation source 14 in order to obtain the signal S ⁇ , as described above.
  • the processor 46 monitors a switch 60 (FIG. 6).
  • the switch 60 assumes an open position or a closed position responsive to the opening or closing of a door to a test chamber that holds the cuvette containing the sample 12 while the sample 12 is tested for the desired-element concentration.
  • other manual or automatic means for detecting whether the cuvette has been put in the test chamber and/or the test chamber door has been closed may be used, e.g., using optoelectronic sensors, load cells or by displaying a message and requesting operator confirmation that the cuvette is in place and the test chamber door is closed.
  • the switch 60 or the other detection means detects whether the test chamber is empty or whether the test chamber door is open. Responsive to the "open" or “empty” detection, the processor 46, under the control of a suitable control program, signals the operator to put a cuvette containing a known concentration of desired element-label means complex into the test chamber. Such signalling is achieved by displaying a message on a CRT display terminal, or by using other signalling means, e.g. lights or audible alarms.
  • Block 120 of HG. 7A represents the signalling of the operator to place the cuvette in the test chamber and to close the test chamber door.
  • the processor 46 Upon detecting that the cuvette is in the test chamber, as represented by block 130, the processor 46, responsive to the control program, activates solenoid 23 which opens electro shutter 29 (HG. 6) thereby directing radiant energy into the sample-containing cuvette as explained hereinabove. After a sufficient delay to allow transient responses to dissipate, as represented by block 150, a measurement is made of the intensity of the radiation source 14 is made in order to obtain the signal S ⁇ (block 152), as described above.
  • the source intensity is checked to obtain the signal S M (block 154)
  • the output of the fluorescence detector 20 is read to obtain the fluorescence signal S F (block 160)
  • the output of the t__msmission detector 21 is read to obtain the transmissive signal S T (block 170), and such signals (which are read as output voltages) are then corrected as required (block 172).
  • the recordation of the output voltages may be achieved via analog-to-digital conversion means coupled to the PC 46 or by the digital output ports of the DVM's 42 and 52.)
  • the electro shutter 29 is closed.
  • the processor 46 uses the voltages to mathematically calculate values for the above mentioned constants, i.e., l/ctt ⁇ t K, S 0 , and T 0 . This calculation is represented by block 190. In the preferred embodiment, the steps indicated at blocks 120, 130,
  • 140, 150, 152, 154 160, 170, 172 and 180 are repeated or iterated 12 times, thereby achieving highly accurate approximated constants, as indicated at block 190.
  • the apparatus 11 is calibrated to measure unknown desired element concentrations.
  • the processor or PC 46 signals the operator to put the cuvette containing the unknown concentration of desired element- label means in the test chamber. The operator then places the cuvette containing the unknown sample into the test chamber. After sensing that the cuvette is in place and that the test chamber door is closed, represented by block 210, that the cuvette is in place and that the test chamber door is closed, the processor 46 (as controlled by the control program) activates solenoid 23 which opens the electro stop 29, thereby directing radiant energy into the cuvette containing the sample 12. The opening of the electro stop is represented by block 220.
  • the processor 46 reads and stores the output voltage or signal S ⁇ l from the source detector 15, the output voltage or signal S F from the fluorescence detector 20, and the output voltage or signal S ⁇ from the transmission detector 21, after which the electro stop is closed. Such reading and storing is represented by blocks 232, 240 and 250 in HG. 7B.
  • the processor 46 After reading the output voltages of the source detector 15, the fluorescence detector 20, and the transmission detector 21, the processor 46 corrects such readings for any variations that may have occurred in the intensity of the source radiation using the above-described correction method. Such correction is represented by block 252.
  • the processor calculates the desired element concentration using the above-mentioned formulas, Eqs. (1) and (2), or uses other means for approximating the desired element concentration based on the amplifier output voltages. That is, the processor 46 calculates a first concentration based on the fluorescence detector output, and a second concentration based on the transmission detector output. The processor 46 then compares the first and second concentrations with a reference value as mentioned above.
  • the reference value is selected to be a desired element concentration in the overlap range or in the range of accuracy for both the fluorescence formula and the transmission formula. If the concentrations are below the reference value, the first concentration, based on the fluorescence detector output, is used or selected as an indication of the concentration. If the concentrations are above the reference value, the second concentration, based on the transmission detector output, is used or selected as an indication of the concentration.
  • the selection of the appropriate concentration is represented by block 260. In this way, the more accurate concentration is used as an indication of the gold (or other metal) concentration.
  • the appropriate equation is then used to calculate the concentration 5 (block 270). This selected concentration is then displayed by the processor 46 (block 280) and/or suitably recorded by the processor 46.
  • the processor 46 signals the operator to indicate whether additional unknown-desired-element-concentration samples to be tested (block 280) If the operator indicates that additional samples are to be tested, the steps represented 10 by blocks 200, 210, 220, 230, 232, 240, 250, 252, 260, 270 and 275 are repeated or iterated. Such repetition continues until the operator indicates that there are no more samples to be tested. In this way, multiple unknown samples can be accurately tested for desired element concentrations, and the most accurate detection means, i.e. fluorescence detection or transmission detection, can be utilized in response to a * 15 programmable controlled processor 46.
  • the most accurate detection means i.e. fluorescence detection or transmission detection
  • all of the components of the preferred embodiment 11 are sufficiently small and light weight so that they may be easily transported, e.g., in a trailer, truck, van, by backpack or the like, thereby allowing the entire apparatus to be portable and easily transported to a field location where soil or rock samples are 20 to be assayed.
  • the second embodiment advantageously eUminates the need for the fiber optic bundle, thereby eliminating the problems associated with the use of a fiber optic bundle, e.g., cracking, while providing a larger overall range of accuracy by using both a fluorescence detector 20 and a transmission detector 21.
  • the advantages of the first embodiment and 25 other advantages are maximized and the disadvantages of the first embodiment are minimized.
  • a small and light weight device is provided that is adapted for transport in a back pack.
  • Such small, portable unit hereafter the "back-pack unit”
  • back-pack unit is battery powered, thereby allowing the analysis to be carried out at remote locations where other power sources are not readily available.
  • a flashlamp is used as the source of radiant energy 14 (FIG. 5) rather than a laser.
  • the flashlamp provides a very short pulse or “flash" of intense radiation, similar to the flash provided from a flash camera.
  • Such pulse or flash of radiation is then optically filtered, as needed, in order to significantly attenuate all wavelengths except the wavelength of interest, ⁇ ,. (It is noted, of course, that even a laser may be pulsed.)
  • the back-pack unit also employs three separate sensors or detectors.
  • a first sensor detects the intensity of the radiation from the source 14 ( ⁇ , detector 15).
  • a second sensor detects the intensity of the radiation that fluoresces from the sample ( ⁇ 2 detector 20).
  • a third sensor detects the intensity of the radiation transmitted through the sample ( ⁇ detector 21). Because the intensity of the source 14 from a typical flashlamp varies a great deal from flash to flash, the use of the ⁇ , detector 15 to detect the intensity of the ⁇ j radiation at the source, thereby allowing the readings at the ⁇ j transmissive detector 21 and the ⁇ 2 fluoresced detector 20 to be corrected for such variations as described above, becomes extremely important to the successful operation of the back-pack unit.
  • a typical flashlamp that may be used with the back-pack unit is the XLS-542 flashlamp, available from Xenon Corp. of Wobum, Massachusetts.
  • the weight of the back-pack unit is less than about four (4) kg (8 lbs.); and its approximate volume, including battery, is no more than about 16000 cm 3 (1000 in 3 ).
  • the flashlamp is powered using a conventional power supply that steps up the voltage from the battery (e.g., 9 volts) to a suitable flashlamp operating voltage (e.g., 600 volts).
  • the sensors 15, 20 and 21 consume very little power
  • the PC (computer) 46 when used, may be of a laptop or notebook size, which computers are already made for portability.
  • Samples are prepared carefully to obtain representative ore samples.
  • the ore samples are roasted under oxidizing atmosphere in the temperature range of 600-800°C for about one hour.
  • Gold (Au) is leached out by turribling the ore in potassium cyanide/potassium hydroxide solution in the presence of hydrogen peroxide.
  • the cyanide extract is then acidified with hydrochloric acid in the presence of hydrogen peroxide at about 90°C.
  • the resulted AuCl 4 " complex is removed from interference ions by tumbling with pretreated poly(dibenzo 18-crown-6) beads in 0.6 M HCL
  • the polymer beads selectively trap AuCI ⁇ complex leaving the interference ions in HCL
  • AuCV is recovered by tumbling the AuCV loaded beads with acetone, the acetone is further evaporated in the presence of H ⁇ leaving AuCV in HCL
  • the AuClf is labelled with Rhodamine B dye.
  • the AuCV- dye complex is further extracted into diisopropylether, and the fluorescence transmittance of the complex is measured.
  • Table 1 The results of Table 1 are plotted in Figure 4, which reveals a smooth non-linear response over a wide range of concentrations.
  • the invention technique was employed to estimate the amount of gold present in two rock samples; these sample were designated samples "A” /and "B", and were independently determined by fire assay analysis to contain about 1325 and 1660 ppb of gold, respectively.
  • the fluorescent signals for samples "A” and “B” were 970 and 1120 MV (after subtracting the values for a zero control sample), corresponding to about

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Abstract

Un procédé et un appareil permettent d'effectuer rapidement des analyses concernant l'or, par exemple dans des échantillons de sols ou de roches. Il convient de mettre la solution contenant de l'or en contact avec un agent d'oxydation et au moins un éther couronné, puis de séparer le complexe or-éther couronné des composants restants de la solution ; on récupère alors les ions d'or dans le complexe or-éther couronné puis on met la solution résultante contenant de l'or en contact avec un agent de marquage tel qu'un chromophobe, après quoi on mesure la quantité d'agent de marquage lié qui se trouve dans la solution. L'appareil (10, 11) comprend une source optique (14) qui illumine le complexe échantillonné (12) avec un rayonnement incident sur une première longueur d'onde, un détecteur (20) qui détecte la lumière rendue fluorescente sur une deuxième longueur d'onde, un détecteur (21) qui détecte la lumière transmise sur cette première longueur d'onde, et un détecteur (15) qui détecte l'intensité du rayonnement de la source. Un processeur (46) corrige la lumière détectée rendue fluorescente, et la lumière trsnsmise, des variations d'intensité relatives au rayonnement incident et détermine séparément la teneur en or sur la base de la lumière détectée rendue fluorescente et de la lumière émise, telles que respectivement corrigées, et choisit celle des deux mesures qui représente le plus fidèlement la teneur en or.
EP92921528A 1991-10-01 1992-09-30 Titrage rapide de l'or et instrument connexe Withdrawn EP0606374A1 (fr)

Applications Claiming Priority (3)

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US76953191A 1991-10-01 1991-10-01
PCT/US1992/008363 WO1993007472A1 (fr) 1991-10-01 1992-09-30 Titrage rapide de l'or et instrument connexe
US769531 2004-01-30

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JP (1) JPH07501882A (fr)
AU (1) AU2768692A (fr)
BR (1) BR9206580A (fr)
CA (1) CA2119134A1 (fr)
CZ (1) CZ76194A3 (fr)
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WO (1) WO1993007472A1 (fr)

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DE10122109A1 (de) * 2001-05-08 2002-11-14 Mbr Gmbh Verfahren und Vorrichtung zur Erfassung einer Stofffraktion insbesondere in einem Kraftstoff
US8582106B2 (en) 2007-11-09 2013-11-12 Hach Company Automatic optical measurement system and method
RU2459201C1 (ru) * 2011-05-20 2012-08-20 Федеральное Государственное Автономное Образовательное Учреждение Высшего Профессионального Образования "Сибирский Федеральный Университет" Способ определения золота
GB2509716B (en) 2013-01-09 2018-07-04 International Moisture Analysers Ltd Spatial Interference Fourier Transform Raman chemical analyser
AT513863B1 (de) * 2013-02-15 2014-12-15 Vwm Gmbh Verfahren und Vorrichtung zur Bestimmung einer Konzentration einer fluoreszierenden Substanz in einem Medium
CN105294677B (zh) * 2015-09-30 2017-04-12 河北大学 一种芳基‑炔化合物及其制备方法和用途
CN112378940B (zh) * 2020-09-30 2024-03-01 长春黄金研究院有限公司 一种载金矿物含金量的测量方法

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US4117338A (en) * 1977-05-24 1978-09-26 Corning Glass Works Automatic recording fluorometer/densitometer
GB2096352B (en) * 1981-04-02 1985-04-11 Abbott Lab Fluorescence spectroscopy
US4495293A (en) * 1983-02-24 1985-01-22 Abbott Laboratories Fluorometric assay
US4945250A (en) * 1989-07-12 1990-07-31 Pb Diagnostic Systems, Inc. Optical read head for immunoassay instrument

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Publication number Publication date
CZ76194A3 (en) 1994-11-16
HU9400943D0 (en) 1994-06-28
HUT66407A (en) 1994-11-28
WO1993007472A1 (fr) 1993-04-15
CA2119134A1 (fr) 1993-04-15
AU2768692A (en) 1993-05-03
JPH07501882A (ja) 1995-02-23
BR9206580A (pt) 1995-10-31

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