CZ76194A3 - Method of quick determination of element content and apparatus for making the same - Google Patents

Abstract

A method and apparatus for performing rapid gold analyses, e.g., in soil or rock samples. The method comprises contacting the gold-containing solution with an oxidizing agent, and at least one crown ether; then separating the gold-crown ether complex from the remaining components of the solution; then recovering the gold ions from the gold-crown ether complex; then contacting the resulting gold-containing solution with a label means such as a chromophobe, and thereafter measuring the amount of bound label means in the solution. The apparatus (10, 11) includes an optical source (14) that irradiates a sample complex (12) with incident radiation of a first wavelength, a detector (20) that detects fluoresced light of a second wavelength, a detector (21) that detects transmitted light of the first wavelength, and a detector (15) for detecting the intensity of the source radiation. A processor (46) corrects the detected fluoresced and transmitted light for variations in the intensity of the incident radiation, and separately determines the gold concentration based on the respective corrected fluoresced and transmitted light, and selects which of the two measurements represents the most accurate measure of the gold concentration.

Description

Method for the rapid determination of the contents of an element and a device

Technical field

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The present invention relates to analytical methods. In particular, the present invention relates to methods and apparatus for rapidly determining the content of gold or other element, particularly low gold concentrations in stone or soil samples. The present invention also relates to analytical methods and instruments that are fast and portable so that they are useful for field applications.

BACKGROUND OF THE INVENTION

Most of the gold deposits currently discovered are made of gold grains that are invisible by a common microscope. These gold particles are often smaller than one micron. Because this gold is not detectable by any readily available portable means, the exploration of deposits now depends almost exclusively on reliable analytical techniques that can only be performed in large analytical laboratories. Such devices are necessarily large and static. Research teams must therefore identify and deliver geological samples to these static analysis facilities and then wait a week or more for the results of the analysis. This method of detecting valuable mineral content is cumbersome, slow ineffective and expensive. A method of detecting the gold content (and equipment) that could be carried out at or near the exploration site and which could provide a rapid and reliable analysis of very small amounts of gold in the rock would mean a huge improvement in gold prospecting.

At current gold prices, there are economically recoverable rocks containing one millionth of gold. In the course of the research, however, even uneconomical amounts of gold can act as a guide for geologists in finding economically beneficial deposits. It is customary that a five billionths gold content can be an important indication that higher gold content values can be found in the vicinity. Therefore, an analytical technique that is sensitive in the range of billions of golden content would be useful for this purpose.

Most of the gold analyzes currently performed in commercial laboratories use the heat test. Flame testing laboratories are large, intensive equipment that consume large amounts of energy and water and often emit hazardous fumes. Another disadvantage of the heat test is that cross-contamination between samples can easily occur.

At present, neutron activation is the only commercially viable modern analytical technique for determining gold content. However, the requirement for access to a nuclear research reactor makes neutron activation even less achievable than the heat test. Neutron activation also necessarily requires an eight-day cooling period due to the breakdown of short-lived radioisotopes before gold is detected. Therefore, in addition to allowing neutron activation only when a nuclear reactor is available, it is also impossible for it to satisfy the need for rapid analytical techniques.

It is therefore an object of the present invention to provide a simple and rapid method of measuring element concentrations in a sample over a wide range, if possible.

The invention also aims to create a portable device that includes devices ³⁰ and the components necessary for practicing the invention.

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Another object of the invention is to provide a fluorometer for detecting the presence of gold in the sample complex. The sample complex contains a suitable binder to which a portion of the soil or stone sample tested for gold is bound. Desirable u

This instrument is designed to allow fluorescent and transmitted data to be obtained over a wide dynamic range. The aim is to ensure good proportionality between fluorescent and transmitted data and gold concentrations. Another goal is to ensure an overall accuracy of ± 15%.

It is a further object of the present invention to provide a fluorometer and transmission device which avoids an internal filter effect.

Yet another object of the invention is to provide a fluorometer and transmission device that is relatively insensitive to changes in the radiation intensity of the source.

Yet another object of the invention is to combine a methodological procedure with a new fluorometer and transfer / device including a special selection of chemicals, conditions

2θ = processing, instrumentation, circuit arrangement and shielding, which effectively eliminates the effects of foreign signals and background radiation, thereby enabling noise suppression and very small signal reading.

SUMMARY OF THE INVENTION

According to the invention, there is provided a method of detecting an element content capable of measuring gold concentrations over a wide range (i.e., from a few billionths to about 30,000 billionths or more).

The process of the invention comprises, if necessary, dissolving the gold content of the sample, then forming a photosensitive complex with gold, for example Rhodamin B gold complex.

The gold concentration in the sample is then determined by analyzing the gold complex using optical means.

The invention also provides an X-ray apparatus which allows rapid analysis of stone, soil and other samples 5 to determine the gold concentration in these samples. In a preferred embodiment, the apparatus is easily transportable to the site of finding stone or soil samples. The apparatus is easy to operate and ensures accurate determination of the gold content in the samples in a relatively short time, for example in less than three hours. In addition, the apparatus is capable of measuring gold concentrations in a wide range from a few billionths (hereinafter ppb) to approximately 30 thousand ppb.

The invention also relates to a system for determining the concentration of gold in a mining sample, such as a stone or soil sample.

One embodiment of the invention may be described as a method of determining the concentration of gold in solutions containing a sample. This method comprises performing the following steps: (a)

2q 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 an acidic environment under suitable conditions to bring substantially all of the gold ions in solution to their highest oxidation state, and for a sufficient time to allow substantially all of the gold ions in solution to be trapped by the crown ether polymer; (b) separating the gold-crown ether complex from the remaining components of the solution; (c) regenerating the gold ions from the gold complex and the crown ether; (d) contacting the metal-containing solution prepared as described in step ₃₀ in step (c) with marking means capable of binding gold at its highest oxidation state and allowing rapid analysis; wherein contacting is carried out in an acidic medium under suitable conditions to allow substantially all of the gold in solution to bind with the label means, and subsequent separation of the free label means from the solution; (e) measuring the amount of bound label means in solution.

According to another embodiment, the present invention may additionally be described as a method for determining the concentration of gold in a matrix. The method comprises the steps of: (a) contacting the matrix with an aqueous cyanide solution in the presence of an oxidizing agent under alkaline conditions; (b) contacting the solution obtained according to 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 suitable conditions to bring substantially all of the gold ions in solution to their highest oxidation state, and for a sufficient time to allow substantially all of the gold ions in solution to be trapped by the crown ether polymer; (c) separating the gold-crown ether complex from the remaining components of the solution; (d) regenerating the gold ions from the gold complex and the crown ether; (e) contacting the metal containing solution prepared as described in step (d) with a marking means capable of binding gold in its highest oxidation state and allowing rapid analysis; wherein the contacting is carried out in an acidic medium under suitable conditions to allow the binding of substantially all of the gold in solution with the means for marking, and subsequent separation

2 ~ free means for labeling from solution; (f) measuring the amount of means for marking in solution.

A further embodiment of the invention may be described as an apparatus for carrying out the method of the invention. Such a device comprises: (a) means for generating radiant energy in a first narrow wavelength band; (b) coupling means for connecting radiant energy to the prepared scum sample; and (c) detecting means optically coupled to the sample for detecting any transmitted light transmitted through the sample falling within the first narrow wavelength band, or any fluorescent light emitted by the sample falling within the second narrow wavelength band.

In the operation of the device according to the invention, the presence of 0 transmitted or fluorescent light in the first or second wavelength band means the presence of particulate elements, for example gold, in the sample. The intensity or magnitude of the detected transmitted or fluorescent light allows measurement of the concentration of particulate elements in the sample. It is desirable to create a conversion diagram or table, for example, by measuring samples with known concentrations of the particulate element, which allows direct measurement of the fluorescent light measured to the concentration of the particulate element in the sample. Thus, by simply measuring the intensity or size of the transmitted and / or fluorescent light 15 in the first and / or second narrow wavelength band, a suitable and rapid measurement of the concentration of the particulate element in the sample is made.

In one preferred embodiment of the device of the invention 20, an optical fiber is used to conduct radiant energy to and from the test sample to avoid the problem of the internal filter effect common to conventional fluorometers. The internal filter effect causes ambiguous results from the output signal from the detector.

Yet another embodiment of the invention may be described as an analytical system for determining the gold concentration in a mining sample. Such a system comprises: (a) coupling means for binding a portion of the mining sample with suitable marking means, such as Rhodamine B, thereby forming a radiation complex of marking means and gold; (b) irradiation means for irradiating the marking means associated with the test sample with radiant energy falling within the first narrow wavelength band, the irradiation means comprising optical fiber means for bringing radiant energy to the sample and discharging the radiant energy emitted from the sample; and (c) detecting means associated with the optical fiber means for detecting the radiant energy emitted from the sample in the second narrow wavelength band. - - - -—

In the work of this analytical system, the label and metal complex emits radiation energy in the second narrow wavelength band in response to radiation energy in the first narrow wavelength band only if the mining sample bound to the tagging means contains the particulate metal of interest. In addition, since the amount or intensity of the radiation thus emitted corresponds to the amount of metal bound to the marking means, the magnitude of the detected radiation forms a simple and rapid measurement of the metal concentration in the mining sample. A further improvement of the system optionally includes means for automatically converting the detected radiation in a certain band to measure the gold concentration in the mining sample.

Other features and advantages of the invention will be apparent from the following detailed description with reference to the accompanying drawings.

Overview of the drawings

Fig. 1 is a block diagram illustrating basic operations of a first embodiment of a fluorometer constructed according to the invention;

Fig. 2 is a more detailed block diagram of a first embodiment of a fluorometer constructed in accordance with the invention and generally shown in Fig. 1;

₃₀ is a graph showing the permeability of two filters used in the apparatus of FIG. 2; FIG.

Fig. 4 is a typical calibration curve used with or with the apparatus of Fig. 2 to convert the measured fluorescent light intensity into a gold concentration measurement;

Fig. 5 is a block diagram illustrating basic operations of a combination of a fluorometer and a transmission device constructed in accordance with a preferred embodiment of the invention;

Fig. 6 is a more detailed block diagram of a combination of a fluorometer and a transmission device constructed according to the preferred embodiment of the invention and generally shown in Fig. 5;

7A and 7B is a flow chart illustrating the steps of measuring the gold concentration in a sample using the preferred embodiment of FIG.

Throughout the drawings and embodiments, like reference numerals are used for like elements.

DETAILED DESCRIPTION OF THE INVENTION

The following description is the best method of the presently envisaged embodiment of the invention. This description is not intended to be limiting, but is intended solely to describe the basic principles of the invention. The scope of the invention should be determined by the claims.

The present invention provides a method and apparatus for rapidly performing this method for determining the concentration of an element, such as gold, in a material (sample). The method and apparatus have generally been described above. Advantageously, the method of the invention 30 can be carried out in a batch or continuous manner. Where the analyzed material is in a solid form such as ore, stone and the like, it is desirable to first crush the solid material into a fine powder, thereby improving the contacting of the reagents with the solid material components. The ore powder is then roasted in an oxidizing atmosphere at a temperature ranging from 500 to 800 ° C for up to one hour, thereby removing volatile elements and minimizing the likelihood of false results.

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To ensure that substantially all the gold in the solid material is present in the solution, the finely divided powder is placed in an aqueous cyanide-containing solution in the presence of an oxidizing agent such as calcium peroxide, sodium peroxide, potassium permanganate, bromine peroxide, chlorine peroxide and peroxide hydrogen.

Cyanide compounds for use in this dissolution step include sodium cyanide, potassium cyanide, and the like. Currently, potassium cyanide is preferred.

The amount of cyanide used may be varied to provide a final concentration of cyanide in the metal-containing aqueous solution, which typically falls within the range of 0.001 M to 0.5 Μ. At present, the final cyanide concentration is maintained in the range of about 0.1 M. To prevent cyanide loss by hydrolysis or reaction with CO ₂ and to neutralize the acid components in the ore, a base such as potassium hydroxide is added to the cyanide solution.

Contacting a matrix containing crushed metal, p

The 2g cyanide and oxidizing agent is performed under conditions suitable to allow dissolution of substantially all of the metal contained in the matrix.

Once the gold is leached into the cyanide solution, the solution is treated with an oxidizing agent (e.g.

3 ° H ₂ O ₂ ) and hydrochloric acid. The oxidizing agent oxidizes gold from valence state +1 to valence state +3. The function of hydrochloric acid is twofold: one is the destruction of cyanide, the other is the securing of the chloride bond for the Au ³⁺ ions. After this step, the gold is in the form of AuCl ₄ ', which is suitable for the next disruption removal step using a crown polymer of ether. The AuCl / molecular complex can be trapped in the cavities of ether crown polymers with an HCl concentration of 0.1 to 6 M.

By selecting an HCl concentration of, for example, 0.6 M, AuCl ₄ 'is absorbed by the polymer and most other metal compounds are left.

A key aspect of the present invention is the discovery that the crown ether polymer obtainable from any commercial θ source must be pretreated to consistently regenerate the gold complex, especially if the gold concentration in the sample is below about 1000 ppb. The difference in the recovery of gold content is due to adsorption sites with a dimension other than that of the gold complex that will capture the gold complex molecules but will not release them at a later stage. The pretreatment of the present invention requires the crown polymer of the ether to be filled with some metal compounds (e.g. Ga, As, Fe, Au) to fill the adsorption sites, and subsequent extraction of most of the metal compounds from the cavities leaving unsuitable spots. This treatment provides an approximately 40% improvement in the regeneration of the gold complex concentration in the 100 ppb range.

Any crown ether polymer capable of forming a metal complex whose concentration is detected is suitable for use in the method of the invention. An example of a crown ether polymer is poly (dibenzo-18-crown-6), i.e. poly (DB18C6), and the like. The amount of crown ether polymer used ranges from 20 to 100 mg / ml metal-containing solution.

The crown metal ether of the bonded metal is then separated from the remaining components / solution. This separation can be easily accomplished by removing the liquid from the particulate material using standard techniques such as decanting, filtration, suction or the like. It is preferable to remove substantially all foreign compounds and then wash the particulate material with 0.6 M HCl.

It is preferred that the separation of the crown ether polymer be carried out in a column. Indeed, if a column is used for separation, the separation time is significantly reduced than when using other separation techniques, for example in a drum. For example, the separation of the crown ether polymer in the drum may take 2.5 hours, but it may also take only 30 minutes if carried out in the column.

Once the gold-crown ether complexes are separated from the remaining components of the metal-containing solution, the ions are regenerated from the complex. This is done, for example, by extracting these ions from the complex using organic solvents containing polar oxygen such as alcohol, ketone, and the like. Preferably acetone (ketone) is used.

When gold ions are regenerated from the crown ether,

2q, the organic extracting agents are removed from the sample by gentle heating in the presence of an oxidizing agent (e.g. H ₂ O ₂ ) to prevent Au reduction, and the material is contacted with the marking means. In this context, means for marking are chemical compounds which are capable of binding to AuCl ₄ 'and which are also capable of being easily analyzed. Exemplary labeling means include chromophores, metal complex agents that are capable of fluorescence upon excitation by incident light of a certain wavelength, and the like.

Examples of labeling means are ³⁰ Rhodamine B (i.e. N- (9- (2-carboxyphenyl) -6- (diethylamine) -3Hxanthen-3-ylidene) -N-ethylethanaminium chloride; brilliant green, PQPP (i.e. 2-phenylbenzo) [8,9] -quinolizino [4,5,6,7-fed] phenanthridinylium cation), etc. Rhodamine B is currently the preferred labeling agent because it provides very low levels of background fluorescence in determining gold concentration.

Sufficient binding between AuCl 3 and the dye is achieved by swirling the mixture for several seconds at room temperature. After this treatment, it is desirable to separate substantially all of the free labeling means in order to reduce background noise in the analysis of the invention. Such removal may, for example, be accomplished by extracting the label agent-metal complex with an organic solvent (e.g., C ₆ H ₆ , ether, preferably diisopropyl ether) from the aqueous solution in which the complex is formed.

The removal of the free marking means described above should be carried out so that a significant amount of these marking means does not remain in the sample to be analyzed.

Once sample preparation is complete, it is advisable to analyze the sample relatively quickly to reduce the possibility of sample degradation. The sample prepared in this way is suitable for the analysis of gold content. The analysis of the metal according to the invention is carried out by determining the amount of marking means bound by the sample. If the marking means are capable of emitting fluorescent radiation upon excitation, the analysis may be performed by exciting the marking means at a certain wavelength and then measuring the radiation intensity at a certain wavelength different from the wavelength used for excitation. The various means used in the apparatus for carrying out this analysis according to the invention are described below. Alternatively, if the labeling means is a chromophore, the analysis may be performed by a spectrophotometric device, i.e. by measuring the amount of radiation absorbed by the sample as it passes through radiation of known intensity through the sample.

A first embodiment of the device according to the invention allows the above described analytical method to be performed by providing a fluorometer which enables rapid field analysis at or near the site of collection of soil or stone samples tested for gold content. A block diagram showing the basic components of the fluorometer 10 constructed in accordance with the invention is shown in Fig. 1. These essential components include a radiant energy source 14, a dichroic mirror 16, an optical fiber 18, and a detector 20. A second detector 15 may also be used. The dichroic mirror 16 is positioned to direct the radiant energy generated by the radiant energy source 14 to the optical fiber 18. The detector 20 is positioned relative to the dichroic mirror 16 to receive radiant energy emitted from the optical fiber 18. The second detector 15 is positioned to receive radiant energy from the radiant energy source 14 to detect variations in radiant energy intensity over time. If these changes are not corrected, they may cause a measurement error generated by the device.

A sample 12 containing a suitable labeling means such as Rhodamine B to which the desired element such as gold (if present) has been attached is prepared as described above in connection with the method of the invention. If sample 12 contains gold, the gold-Rhodamine B complex fluoresces in the spectral region

560 to 580 nm when excited by radiant energy (light) at

5 spectral regions 540-550 nm. When sample 12 is a complex of gold and PQPP, excitation in the region of about 300 nm results in fluorescence in the spectral region of about 460 nm. It is preferred that the amount of radiation emitted is a monotonically increasing function of the concentration of gold in the complex.

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To determine the gold concentration in the sample 12, the fluorometer 10 operates as follows: The radiant energy source 14 generates radiation of the first wavelength λ _ν where λ falls for 540-550 nm for the gold a Rhodamine B complex (for the gold and PQPP complex is λ, about 300 nm). This radiation is directed through the dichroic mirror 16 to the optical fiber 18, and is also directed to the second detector 15. The sample 12 in response to radiation λ! it fluoresces radiation of the second wavelength λ ₂ , where λ ₂ falls for the complex of gold and Rhodamine B in the range of 560 to 580 nm (for the complex of gold and PQPP is λ ₂ around 460 nm). The radiation λ ₂ is passed from the sample 12 through the optical fiber 18 through the dichroic mirror 16 to the detector 20. The detector 20 is adapted to detect the amount of radiation having a wavelength λ ₂ . This detection thus ensures a direct measurement of the gold concentration in the sample 12.

The output intensity of the radiation source 14 will fluctuate to some extent during the measurement of the plurality of reference samples and samples 12. In order to minimize errors caused by the fluctuation of the intensity of the radiation source 14, the second detector 15 allows monitoring of this intensity so that determining the gold concentration as described below.

²⁰ Optical fiber 18 is readily accessible and can be constructed of various materials including silica, glass, polymethylmathakrylátu, polycarbonate, polystyrene, and the like. Commercially available optical fibers can be used without any special treatment prior to use. The only treatment is usually to remove the sheath from the fiber from parts that will be directly exposed to the sample.

The basic requirement for the selection of a single optical fiber, the stability of the sensing material ₅₀ when exposed to a solvent system and the metal analyzed, and the degree, if any, with which tend sensor material and sample components interact, giving rise to interference in the analysis. If an unstable signal is obtained, to overcome this problem, it is appropriate to consider using another optical fiber, another solvent system for analysis, and / or other marking means.

FIG. 2 shows a more detailed block diagram 5 of one embodiment of a fluorometric device constructed in accordance with the invention. (It is already stated that the same reference numerals are used for the same elements in Figs. 2 and 1.) As is apparent from Fig. 2, the apparatus comprises the same basic components as the apparatus in Fig. 1, i.e., radiant energy source 14. The dichroic mirror 16, the optical fiber 18, the detector 20 and the second detector 15. As in FIG. 1, the optical fiber 18 directs radiation to and from the sample 12 being tested.

As seen in FIG. 2, the radiant energy source 14 includes a current source 22 connected to a broadband light source 24. The light generated by the broadband light source 24 is guided 15 by a suitable optical system 27 to the filter 30. The optical system 27 includes any suitable means for efficiently supplying radiant energy from the broadband light source 24 to the filter 30. The filter 30 is a narrowband filter and filters all energy except ₂ θ required wavelength λ _ν (It must be understood that λ may consist of a narrow wavelength band as well as a single wavelength depending on the filter bandwidth of 30.)

As shown in FIG. 2, the optical system 27 includes an optical line 26 with one end optically coupled to the broadband light source 24 and the other end at the focus of the lens 28. Thus, radiant energy from the broadband light source 24 is guided through the optical line 26 to the lens 28. is directed to the filter 30.

After passing through the filter 30, only a narrow band of radiant energy remains, for example, at a wavelength λ _ν. The radiant energy at this wavelength λ is optically reflected by the dichroic mirror into the additional lens 32 to be guided or directed into the optical fiber 18.

Furthermore, it can be seen from FIG. 2 that the fluorescent light from sample 12 is emitted from the optical fiber 18 and is directed back into the dichroic mirror 16 by the additional lens 32. This fluorescent light passes through the dichroic mirror 16 to the detector 20. The detector 20 comprises a narrowband filter 34 arranged. for transmitting radiation of wavelength λ _{2 only} . (It must be understood that λ ₂ may consist of a narrow wavelength band as well as one wavelength.) Thus, radiation or light of a wavelength other than λ _{2 is} considerably limited by the narrowband filter 34. Thus, if sample 12 contains the desired element, for example gold, the fluorescence radiation will fall within the wavelength range λ ₂ and will pass through the narrowband filter 34.

After passing through the narrowband filter 34, radiation is guided or directed by the second lens 36 to the photodetector 38. The photodetector 38 operates in a conventional manner and detects the amount of incident radiation. Thus, any radiation of wavelength λ ₂ that passes through the narrowband filter 34 is detected by the photodetector 38. In response to this incident radiation, the photodetector 38 generates an electrical signal. The amplitude of this signal corresponds to the intensity of the detected radiation. The electrical signal generated by the photodetector 38 is amplified by the amplifier 40. The output signal of the amplifier 40 can then be recorded to determine how much radiation or light of wavelength λ ₂ was detected by the photodetector 38. A large output signal means radiation with a wavelength λ ₂ of high intensity. means a high concentration of particulate element in sample 12 (assuming a uniform sample volume of 12). Similarly, a small output signal means radiation with a wavelength λ ₂ of low intensity, which in turn means a low concentration of the particulate element in a uniform sample volume 12. Preferably, as explained in more detail in connection with FIG. to provide a direct measurement (e.g. in ppb) of the element concentration in the sample 12.

As shown in FIG. 2, the output-signal-amplifier 40-5 is measured by a digital voltmeter (DVM) 42. In addition, if desired, this output voltage can be recorded or stored in the data logger 44. or in an appropriate device.

In addition, for some applications, it may be appropriate to connect a suitable processor 46, such as a portable personal computer (PC), to the output voltage of amplifier 40. This connection can be made directly from the output signal of the amplifier 40 if the processor 46 includes internal means for an analog-to-digital (hereinafter A / D) conversion (for converting the analog output signal of the amplifier 40 to a digital signal suitable for PC processing); or, alternatively, if the DVM 42 includes digital output, as is common with many commercial digital voltmeters, this connection can be made from the DVM 42 to the processor 46.

The processor 46, if used, provides various processing functions associated with the output signal of the amplifier 40. For example, the processor 46 may include a lookup table or equivalent (e.g., an equation) stored therein to allow direct conversion of the measured output voltage of the amplifier 40 to a concentration value. required element. In addition, the processor 46 may include various digital processing steps that analyze the output voltage of the amplifier 40 over a period of time to further refine this data, for example by removing noise using conventional digital filtering techniques.

In the further description of FIG. 2, it can be seen that the second detector 15 is wU positioned to receive radiation of wavelength λ ₁ generated by the radiation energy source 14. This radiation is passed through an additional lens 29 to the second photodetector 39. The second photodetector 39 operates in a conventional manner and detects the amount of incident radiation. Thus, any radiation of wavelength λ from the radiation energy source 14 passing through the filter 30 is detected by a second photodetector 39. If desired, additional filters placed in front of the additional lens 29 may be used to filter all radiation except wavelength λ _ν In response to the incident radiation of wavelength λ ₁ generated by the second photodetector 39 an electrical signal. The amplitude of this signal corresponds to the intensity of the detected radiation. The electrical signal generated by the second photodetector 39 is amplified by the second amplifier 41. The output signal of the second amplifier 41 is then recorded to determine how much radiation or light having a wavelength λ ₁ was detected by the second photodetector 39. A large output signal means radiation with a wavelength λ ₁ of high intensity . Similarly, a small output signal means radiation with a wavelength λ ₁ of low intensity.

The output signal of the second amplifier 41 is measured by a second digital voltmeter (DVM) 43. In addition, if appropriate, this output voltage may be recorded and / or stored in a data logger 45 or equivalent device. In addition, for most applications, it is convenient to connect the output of the second amplifier directly to the processor 46, which may be a PC. This output signal can then be used to produce a reference signal that indicates changes in radiation intensity at wavelength λ _ν

Thus, in operation, the second detector 15 records the intensity of radiation of wavelength λ from the radiation energy source 14. If the initial sample is measured, the measured intensity is the reference signal S _Ref . For further measurements, the intensity of fluorescence radiation of wavelength λ _{2 is} indicated as the signal S _F. Advantageously, the signal S _F corrected when changing the intensity of radiation of wavelength λ ₁ in the following manner:

S _C orr signálu (F F · S _Ref ) / S _X1 where S _corr represents the signal correction S _F , and S _Z1 represents the current radiation intensity of the radiant energy source 14 measured by the second detector T5r Preferably, by maintaining the signal 5

With _Ref in the processor 46 or equivalent, the described correction can be made by the processor 46 for each measurement performed.

Another embodiment of detector 20 may include a plurality of filter-photodector-amplifier assemblies, each designed to sense radiation of a particular wavelength. The output signals from all such assemblies can then be monitored, for example, using a processor 46 to provide overall information about the contents in the sample complex, including determining the concentrations of the amount of elements in the sample complex.

As an alternative embodiment of the radiant energy source 14, a conventional laser, for example a He-Ne laser, having an output wavelength of 543.5 nm can be used. The narrow output of this He-Ne laser ₂₀ can be coupled by any suitable means directly to the optical fiber 18, with only a small portion of this output being routed directly to the second detector 15. Usually such a connection utilizes at least a dichroic mirror 16 and an additional lens 32 thereby allow the laser to be positioned off the axis of fluorescent radiant energy emanating from sample 12.

Fig. 3 is a graph illustrating the transmission properties of the filter 30 and the narrowband filter 34 used in the apparatus of Fig. 2. These transmission properties are selected for the detection of gold or the gold-Rhodamine B. Of course, it should be ³⁰ understood that similar properties can be selected for the detection of other gold complexes. The first peak or first band 70 is positioned at approximately 545 nm. This first band 70 represents the desired transmission properties of a filter 30 that is coupled to a broadband light source 24. The second peak or second band 72 is located at approximately 580 nm. This second band 72 represents the desired transmission properties of the narrowband filter 34 located in front of the photodetector 38. If a He-Ne laser is used in place of the broadband light source 24, its wavelength is 543.5 nm, which roughly corresponds to the first band 70.

When other complexes are detected, the location of the first band 70 and the second band 72 should be selected accordingly. Θ For example, if a given sample emitted fluorescent radiation at a wavelength of 590 nm when exposed to radiation at 520 nm, then the first band 70 at 520 nm and the second band should be at 590 nm.

Figure 4 shows a typical calibration curve 5 used with or the apparatus of Figure 2 to convert the measured fluorescent light intensity into a gold concentration measurement. It must be noted that other equivalent calibration techniques of converting the measured fluorescent light intensity to the gold concentration measurement may also be used, such as using a ³ table or equation. The curve of FIG. 4, or an equivalent table or equation, is generated by measuring the amplitude of a fluorescent signal for a series of uniform volume samples containing known gold concentrations. In Figure 4, only the portion of the total calibration curve that can be obtained is shown. In general, a good calibration value is obtained using the fluorometer of the invention over a wide dynamic range, for example from 10ppb to 3000 ppb. In addition, the fluorometer of the invention is able to measure differences in the concentration of the order of 1 ppb with a system response time of the order of one second. The accuracy of the combined chemical and optical method from the original samples is approximately ± 15%.

It is preferred that the use of optical fiber 18 avoids a measurement problem known as the internal filter effect and common in known spectrofluorometers. This problem results in the amount of fluorescent light emitted reaching a peak level at low metal concentrations and then decreasing with increasing metal concentration. This internal filtering effect thus results in a two-valued output and unreliable results in the range of metal concentrations of interest. For more information, see; 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).

Referring to Fig. 2, the broadband light source 24 may be comprised of Xenon Are (ILC No.131), a thermal light source, such as the Gilway Technical Lamp No. L7394, or

Helium-Neon laser (No. LSGR-0150M, obtained from Particle Measuring Systems (PMSj). As shown below, it is preferred to use a He-Ne Laser, but other sources can also be used. Broadband light source 24 is located at the focal point Optionally, light can be transmitted to the focal point of lens 28 through optical line 26. If used, optical line 26 can be implemented using a fiber having a diameter of 1000 microns. , such as from Ensign-Bickford.

The collimated (focused) beam through the lens 28 is transmitted 25 by a filter 30, which may be Part No.546BP10, supplied by Omega Optical Inc. The dichroic mirror 16 may also be supplied by Omega Optical Inc, such as Part No.440 DES P. The additional lens 32 directs light at the end of the optical fiber 18. This additional lens 32 may be an aspherical lens.

No.06-3097, supplied by Spindler & Hoyer. The optical fiber 18 may preferably be a fiber having a diameter of 1000 microns, for example from Ensign-Bickford. Narrowband filter 34, which is guided by fluorescent light, can also be supplied by Omega

Optical Inc, as Part No.577BP10. The second lens 36 may be the same as the additional lens 32. The photodetector 38 may be any suitable photodetector, such as a photodiode detector, which is commercially available in many types, for example the silicon photodiode No.S2386 manufactured by Hamamatsu.

The electrical signal from the photodiode detector is amplified by an amplifier 40. For this purpose, an operational amplifier with low noise and low drift is suitable. Very suitable for this purpose is the Burr-Brown No.OPA128LM amplifier. The amplified output of the amplifier 40 is preferably printed and stored by a data logger 44, which may be supplied by Omega Engineering Inc, such as Part No.OM-550. The DVM 42 may be provided by any suitable manufacturer.

The components of the second detector 15 may be the same as the corresponding components of the detector 20.

The particular component selection described above in connection with FIG. 2 preferably allows sensing of exceptionally low fluorescent light values by noise suppression. For example, the preferred amplifier 40 (Burr-Brown NO.OPA128LM) has an ultra-low current bias, a very high signal-to-noise ratio and a summation suppression, thus allowing the photodetector 38 to receive extremely small signals (electrical current) corresponding to small values of samples. The amplifier 40 converts such small signals to a relatively large output voltage.

In addition, for noise suppression, it is important to select optical components for the fluorometric instrument design that provide a large amount of light energy and can operate in a very narrow band without interfering signals (these interfering signals would appear as noise). In a preferred embodiment, the filter 30, the narrowband filter 34, the photodetector 38, the lens 28, the second lens 36, and also the He-Ne laser (if used) are all selected with this in mind. For example, using a He-Ne laser as the radiant energy source 14 in Fig. 2 (instead of a broadband light source 24) to generate a narrow energy band at 543.5 nm with an ________ output, power level of approximately JL5 milliwatt, the photodetector 38 may record changes very low power levels, from samples with extremely low metal content. For this reason, using the He-Ne laser as a radiant energy source 14 is preferable to using it as a broadband source, as shown in Figure 2.

Because of the very low signals and the need for low associated noise, the fluorometric instrument of the invention utilizes suitable shielding in component packages. This shielding is necessary to avoid radiant and electrical interference, for example 55 with background radiation, and is particularly required in the packaging of the photodetector 38 and amplifier 40. Such shielding comprises a special housing 39 housing the photodetector 38, amplifier 40 and components. related to them (for example, a power source). A special housing 39 can be made of any suitable metal θ _2, such as copper or aluminum, which prevents the passage of radiation of low power and which is a good electrical conductor.

In addition, in order to further reduce noise and interfering signals, the optical fiber dimension 18 should be selected for maximum transmission of λ, and λ ₂ signals with minimum noise. In a preferred embodiment, this requirement is achieved by using optical fibers having a diameter of 1000 microns.

Preferably, all components of the fluorometer 10 are sufficiently small and lightweight so that they can be easily transported, for example, in a trailer, truck, van, in hand luggage, and the like thereby rendering the fluorometer 10 portable and easily transportable to the soil or stone surveying area. samples.

A second embodiment of the device according to the invention facilitates the implementation of the above concentration detection method by providing a portable combination of a fluorometer and a transmission device which, like the first embodiment, allows a rapid method of determining concentration at or near the soil or stone samples gold content. In addition, the second embodiment improves the first embodiment by providing a combination of a fluorometer and a transfer device that detects gold concentrations over a wide range (e.g., from a few ppb up to thirty thousand ppb) without the use of optical fiber. By eliminating the need for optical fiber, various problems associated with the placement of the optical fiber and the sample are overcome. By combining a fluorometric instrument and a transmission meter, a much larger range of concentrations of the desired elements can be measured.

A block diagram of a combination instrument 11 that connects a fluorometer and a transmission meter constructed in accordance with a second embodiment of the invention is shown in Fig. 5. As seen in FIG. 5, the combination apparatus 11 includes a radiant energy source 14, a radiation detector 15 from a source, a fluorescent radiation detector 20, and a transmitted radiation detector 21. The fluorescence detector 20 is positioned relative to the sample 12 so as to receive radiant fluorescent energy from the sample 12 when excited by radiation from the radiant energy source 14. The radiation detector 15 from the source w with respect to the dichroic mirror 17 is positioned to receive a small portion of the radiation emitted by the radiation energy source 14. The transmitted radiation detector 21 is positioned relative to the radiation energy source 14 to receive the radiation energy passed through the sample 12.

It is already noted that in optically dense solutions, for example, samples with high ppb gold, the linear extent of the fluorescent signal is limited. To increase this range, the side of the cuvette facing the fluorescence detector 20 is ρ;

$

The light shield 13 with a narrow slit 19 is placed therein. This reduces the path length of the incident light and allows the intensity of the fluorescent radiation to be linearly proportional to the excited light over a larger range.

As in the first embodiment, sample 12 containing suitable marking means to which gold (if present) has been attached is prepared as described above in connection with the method of the invention. If sample 12 contains gold, it fluoresces in the spectral range of about 577 nm and transmits radiant energy to 543.4 nm relative to the radiant energy of the source that emits radiation at 543.5 nm. At low gold concentrations (eg below 2000 ppb), the fluorescence radiant energy intensity mon is a monotonically increasing function - the gold concentration in the sample 12, while at higher gold concentrations (eg above 2000 ppb)

12.

To determine the gold concentration in the sample 12, the combined instrument 11 operates as follows: The radiant energy source 14 generates radiation of the first wavelength λ _ν where λ _ή falls within the range of about 543.5 nm for the gold-Rhodamine B complex. This radiation is directed to sample 12. Sample 12, in response to radiation λ _ή, fluoresces radiation of the second wavelength λ ₂ , with λ ₂ falling around 577 nm for the gold-Rhodamine B complex. Radiation λ ₂ is detected by a fluorescent radiation detector 20. The fluorescence detector 20 is adapted to detect the amount of radiation of wavelength λ ₂ . Moreover, the sample 12 transmits radiation λ _{ν The} transmitted radiation is indicated by λ / in Fig. 5 to distinguish it from the incident radiation λ! and to indicate that the transmitted radiation λ / has a lower intensity than the incident radiation λ _{ν The} wavelengths of the incident radiation λ, and the transmitted radiation λ / are identical. Radiation λ / is detected by the transmitted radiation detector 21. Radiation λ! is detected by a radiation detector 15 from a source. The transmitted radiation detector 21 is adapted to detect the amount of radiation of wavelength λ /. The combination of detecting λ ₂ and λ / thus provides a direct measurement of the gold concentration in the sample 12. Detecting incident radiation by the radiation detector 15 from the source allows appropriate correction of the measurements made by the fluorescence detector 20 and the transmitted radiation detector 21 taking into account changes in source intensity 14 radiant energy.

FIG. 6 is a more detailed block diagram of a second embodiment of the combination apparatus 11. (It is already noted that the same reference numerals are used for the same parts in FIGS. 6, 5, 2 and 1). As seen in FIG. 6, the combined apparatus 11 comprises the basic components shown in FIG. 5, i.e., the radiant energy source 14, the radiation detector 15 from the source, the fluorescent radiation detector 20, and the transmitted radiation detector 21. As further indicated in FIG. 6, the radiant energy source 14 consists of a power supply 22 connected to the narrowband laser 25. The incident light generated by the narrowband laser 25 is guided by an electrical restraint or orifice 29 which is controlled by the solenoid 23 to be either closed or open. The operation of the solenoid 23 in relation to a programmed personal computer (PC) or processor 46, or other control device, is explained in more detail below with reference to FIGS. 7A and 7B. When the aperture 29 is open, the light generated by the narrowband laser 25 is passed through the non-selective filter 31 and the aperture 33 into the sample 12. The non-selective filter 31 reduces the intensity of the light generated by the narrowband filter 25 to a suitable level, .

It can also be seen from FIG. 6 that the fluorescent light or radiation from the sample 12 generated in response to incident light passes into the fluorescent radiation detector 20. The fluorescence detector comprises a light shield 13 with a narrow slit 19, as described above in connection with Fig. 5. In addition, the fluorescence detector 20 comprises a first fluorescence band filter 35 arranged to pass only radiation of wavelength λ ₂ . In a preferred embodiment, the λ ₂₅₇₇ nm. This means that radiation or light with a wavelength other than λ ₂ is considerably attenuated by the first fluorescent band filter 35. Thus, if the sample 12 contains the desired element, for example gold, the fluorescent radiation from the sample 12 will fall within the wavelength band λ ₂ and such radiation will pass through the first filter 35 of the fluorescent band.

After passing through the first fluorescent band filter 35, radiation passes through the second fluorescent band filter 37. The second fluorescent band filter 37 is also arranged to transmit only radiation of wavelength λ ₂ . Thus, the second fluorescent band filter 37 operates similarly to the first fluorescent band filter 35 so as to further attenuate wavelength light of a value other than λ ₂ that passes through the first fluorescent band filter 35.

After passing through the second fluorescent band filter 37, the radiation is routed to the photodetector 38. The photodetector 38 operates in a conventional manner and detects the amount of radiation incident thereon. Thus, any radiation of wavelength λ ₂ that passes through the first fluorescence filter 35 and the second fluorescence filter 37 is detected by the photodetector 38. In response to this detection, the photodetector 38 generates an electrical signal, the amplitude of the signal being proportional to the intensity of the detected radiation. The electrical signal generated by the photodetector 38 is amplified by the amplifier 40. The output signal of the amplifier 40 can then be monitored to determine how much radiation or light with a wavelength λ ₂ has been detected by the photodetector 38. A large output signal means radiation with λ ₂ of high intensity, of the desired element in sample 12 (assuming a uniform sample volume of 12). Similarly, a small output signal means radiation with λ ₂ of low intensity, which means a low concentration of the wanted element in a uniform volume sample 12. Preferably, as will be explained in more detail below, if the output signal can be calibrated to provide a direct measurement (e.g. in ppb) of the element concentration in the sample

12.

As can be seen in FIG. 6, the output signal of the amplifier 40 can be measured by a digital voltmeter (DVM) 42. If desired, this output can be recorded or stored in a data logger 44 or equivalent device.

It can also be seen in FIG. 6 that any light passing through the sample 12, referred to as transmitted light, passes from the sample 12 to the transmitted radiation detector 21. The transmitted radiation detector 21 comprises a viewing window 43 for collimating the transmitted light and bringing it to the desired detection location. In addition, the window 43 helps to minimize light scattering to the transmitted radiation detector 21 from external sources. The light entering through the window 43 is guided through the bandpass filter 45. The bandpass filter 45 is adapted to transmit radiation of only wavelength λ /. In a preferred embodiment, the bandpass filter 45 is set to 546 nm so that it easily transmits the transmitted radiation at a frequency of λ ₁ (543.5 nm). That is, radiation or light of a wavelength other than λ / is significantly attenuated by the bandpass filter 45. Thus, the fluorescent radiation from sample 12 having a wavelength λ ₂ will be greatly attenuated and will thus have minimal effect on the measurement of the transmitted radiation made by the transmitted radiation detector 21. Thus, the radiation transmitted by the sample 12 having a wavelength λ / will pass through the transmitted band filter 45. The light passing through the bandpass filter 45 is passed through a second non-selective filter 47,

which reduces transmitted radiation to acceptable size. 5 After passing through the second non-selective filter 47, the radiation is passed to a second photodetector 48. The second photodetector 48 operates in a conventional manner and detects the amount of radiation incident thereon. Thus, any radiation of wavelength λ / which passes through the bandpass filter 45 and the second non-selective filter 47 is detected by the second photodetector 48. In response to 10 For this detection, the second photodetector 48 generates an electrical signal, the amplitude of the signal being proportional to the intensity of the detected radiation. The electrical signal generated by the second photodetector 48 is amplified by the second amplifier 50, and the output signal of the second amplifier 50 is monitored to determine how much 15 Dec radiation or light with wavelength λ / was detected by the second photodetector 48. A small output signal means a high concentration of the wanted element in the sample 12 (assuming • j uniform sample volume 12). A similarly large output signal means a low concentration of the wanted element in the sample of 12 o 20 May uniform volume. It is preferred that the output signal can be calibrated to provide a direct measurement (e.g. in ppb) of the element concentration in the sample 12. 25 As shown in FIG. 6, the output signal of the second amplifier 50 may be measured by a second digital voltmeter (DVM) 52. If desired, this output may be recorded or stored in a data logger 44 or equivalent device. ί It is already noted that all components displayed on 30 6, for example photodetectors, amplifiers, voltmeters, recorders, lasers, etc., can be realized using the same types of instruments and apparatus as described previously in connection with FIG. 2. In a second embodiment of the invention, the processor 46, or equivalent personal computer (PC), is coupled to the amplifier output

and the output of the second amplifier 50. This connection may be direct if the processor 46 includes internal analog-to-digital (A / D) conversion means (to convert the analog output signal of the amplifier 40 and the second amplifier 50 to a digital signal suitable for processing by the processor 46), or if the DVM 42 and the second DVM 52 contain digital output, as is common with many commercially available digital voltmeters, this connection may alternatively be made from the DVM 42 and the second DVM 52 to the processor 46.

Further details associated with the operation of the embodiment shown in FIG. 6 can be found in copending U.S. patent application Ser. No. 07/769531, filed Oct. 1, 1991, which is incorporated herein by reference.

Preferably, the signals received by the processor 46 from the amplifier 40 and the second amplifier 50 are used to automatically calculate the concentration of the wanted element, for example gold, present in the sample 12. As in the first embodiment, a calibration curve may be generated (or mathematically expressed) as shown. 4, by analyzing sample complexes with known concentrations of the desired element, for example, known concentrations of gold. According to the invention, a first calibration curve is based on the output of the fluorescent radiation detector 20, and a second calibration curve is based on the output of the transmitted radiation detector 21. (The term calibration curve as used herein refers to any means, including a mathematical equation, or other equivalent, relating to the relationship of one variable, i.e., output from a detector, to another variable, i.e., gold concentration.) The first calibration curve is based on known concentrations in the sample complex, and can be mathematically expressed by the equation:

C, = (l / ot..InCK / K - (S - S ₀ ) j (1) where C, is the concentration of gold, S is the output of the fluorescence detector 20, and is the intrinsic absorption constant of the material, I, is the effective cell length and _the K and S are constants. the constants are determined empirically using samples containing known concentrations of gold. Representative values of such constants are al, = .00035, K = 0.755, and S _a = 0.0045 (volts). Unfortunately, it is the ability of equation (1) to accurately estimate the gold concentration is limited to the lower concentration range, for example from 0 ppb to 3000 ppb.

If the concentration range is higher, a second calibration curve is used. The second calibration curve is also derived from known concentrations in the sample complex, and can be mathematically expressed by the equation:

¹⁵ C = (1 / Al ₂₎ ln (T ₀ / T) (2) where C is the gold concentration, T is the output of the transmission detector 21, and 1 / al ₂ and T _o are constants. The constants are again determined empirically using samples with known _2Q gold concentrations. Representative values of such constants are Al ₂ .0000751 = T _o = 1.75 (V). The ability of equation (2) to accurately estimate the gold concentration is limited to the upper concentration range, for example from 1000 ppb to 25000 ppb.

Thus, in operation, after the output signal of the amplifier 40 and the output signal of the second amplifier 50 are generated, the processor 46 calculates the first concentration according to the fluorescence equation (1) and the second concentration according to the transfer equation (2). Because the precision range for fluorescence equation (1) is limited to about 30,000 ppb or less, equation (2) is used for concentrations in the range of 2000 ppb to about 30,000 ppb. Any equation can be used in the overlapping range between 2000 ppb and 3000 ppb. In this way, this second embodiment of the invention provides a significant increase in dynamic range over the first embodiment of the invention.

By using the radiation detector 15 from the source, it is advantageously possible that the signals detected by the photodetector 38 and the second photodetector 48 can be corrected as the radiation intensity of the radiant energy source 14 changes. The dichroic mirror 17 acts as a beam splitter and directs a small portion of the incident radiation (e.g., about 4%) to the radiation detector 15 from the source. The initial value of the intensity of the source of radiant energy 14 is denoted as signal S _Ref, the actual intensity of the source of radiant energy 14 is denoted as signal _X1, the current value of the fluorescence radiation is indicated as signal S _F and the current value of the transmitted light is denoted as the signal S _T . The fluorescence signal S _F and the transmission signal S _T can both be corrected using the following formulas:

Sp (Corr) = (S _p S _Ref ) / S _{x 1}

S _T (Corr) = (S _{T Rtf} ) / S ,,

A more detailed description of the process of the processor 46 in calculating the exact gold concentration is given below with reference to FIGS. 7A and 7B.

The transfer properties of the first fluorescent band filter 35, the second fluorescent band filter 37, and the transferred band filter 45 used in the embodiment of FIG. 6 are selected for detecting gold or gold and Rhodamine B complexes in the same manner as the 30 and narrowband filter properties. 2 of the filter 34 used in the embodiment of FIG. The bandpass filter 45 has a first peak or a first band at approximately 546 nm. The first fluorescent band filter 35, the second fluorescent band filter 37 have a second peak or second band at approximately 577 nm. The narrowband laser 25 produces radiant energy at a wavelength of approximately 543.5 nm, which roughly corresponds to the first band of the bandpass filter 45.

Fig. 7A and Fig. 7B is a flowchart illustrating the manual and program steps used to measure the concentration of the wanted 5 element in the sample 12 using a combination of a fluorometer and a transmission device according to a second embodiment of the invention. Each major step of the method shown in Figs. 7A and 7B is indicated as a block. It is contemplated that those skilled in the art can readily perform the steps shown in Figs. 7A and 7B (in the manual embodiment) or create a suitable program or code for the processor 46 (in the automatic processing).

In Fig. 7A, block 110 represents the preparation of a sample 12 according to the above description of the method of the invention, including contact of the material being prepared with the marking means to which the present gold has bound. After preparing the desired complex of element and labeling means, for example, a gold-Rhodamine B complex, the solution is transferred to a cuvette, or a transparent vessel through which the solution can be irradiated. In addition, during the measurement of the initial reference samples, the radiation intensity of the radiant energy source 14 is measured in order to obtain the signal S _Ref as mentioned above.

After applying power to the combination instrument 11.

the processor 46 monitors the switch 60 (see FIG. 6). The switch 60 is in an open position or a closed position that corresponds to an open or closed door of the test chamber into which the sample cuvette 12 is inserted to determine the concentration of the wanted element in the sample 12. Alternatively, other hand ₃ θ or automatic means may be used. to determine whether the cuvette is inserted into the test chamber and / or whether the test chamber door has been closed, for example using optoelectronic sensors, load cells or displaying a message and requesting the operator to confirm that the cuvette is inserted and the test chamber door is closed.

As soon as the power is supplied to the combination instrument 11 (e.g., after a suitable warm-up time), the switch 60 or other detection means signals whether the test chamber is empty or whether the test chamber door is open. In the open or empty signaling, the processor 46, which is controlled by a suitable control program, tells the operator to insert into the test chamber a cuvette containing a complex of element and labeling means of known concentration. This notification is accomplished by displaying a message at the output of the display unit, or by using other signaling means, such as light or audible signaling. Block 120 in FIG. 7A represents signaling to the operator to insert a cuvette into the test chamber and close the test chamber door.

Upon detecting that the cuvette is in the test chamber, which represents block 130, the processor 46 according to the program activates the solenoid 23 which opens the orifice 29 (FIG. 6), thereby delivering radiant energy to the cuvette containing the sample 12 as above. After sufficient delay to allow the transients, which is represented by block 150, to measure, the radiation intensity of the radiant energy source 14 is measured to obtain an S _Ref signal (block 152). as described above. Further, the radiation intensity of the radiant energy source 14 is controlled to obtain a signal _SX1 (block 154). the output of the fluorescence detector 20 is read to obtain a fluorescence signal _SF (block 160). the output of the transmission radiation detector 21 is read in order to obtain a transmission signal S _T (block 170). and these signals (which are read as the output voltage) are then corrected accordingly (block 172). (As mentioned above, output voltage recording can be performed by analog-to-digital conversion means connected to processor 46 or by DVM 42 and second DVM 52 digital outputs.)

After recording the output voltages generated for the sample 12 with a known concentration of the element sought, the orifice 29 is closed. If a sufficient number of known samples 12 have been measured, the processor 46 will use the measured output voltages to mathematically calculate the above constants, i.e. 1 / α, K,

S _o , and T _o . This calculation is represented by block 190.

In a preferred embodiment, the steps designated blocks 120, 130, 140, 150, 152, 154, 160, 170, 172 and 180 are repeated twelve times to achieve high precision of the determination of the constants indicated by block 190. In this way, the combination instrument 11 is calibrated to measure unknown concentrations of the desired element.

Further, as represented by block 200, the processor 46 signals the operator to insert into the test chamber a cuvette with a complex of the wanted element and labeling means of unknown concentration. The operator then inserts a cuvette with an unknown sample 12 into the test chamber. Upon detecting that the cuvette is stored and that the test chamber door is closed, which is represented by block 210. the processor 46 (thus controlled by the control program) activates the solenoid 23 opening aperture 29 is represented by block 220. After sufficient delay to allow the transients to disappear, represented by block 230, the processor 46 reads and stores the output voltage or signal S _X1 from the radiation detector 15 from the radiation detector 15. source, output voltage or signal S _F from the fluorescent radiation detector 20, and output voltage or signal S _T from the transmitted radiation detector 21, then the orifice 29 is closed. This reading and storing is represented by blocks 232.

240 and 250 in FIG.

After recording the output voltages of the radiation detector 15 from the source, the fluorescent radiation detector 20, and the transmitted radiation detector 21, the processor 46 corrects these values according to various changes that may have occurred in the radiation intensity from the radiant energy source 14 using the correction method described above. This correction is represented by block 252. Further, the processor 46 calculates the search element concentration based on the above equations (1) and (2), or uses other means to determine the search element concentration based on the amplifier output voltages. That is, the processor 46 calculates a first concentration based on the output of the fluorescent radiation detector 20 and a second concentration based on the output of the transmitted radiation detector 21. The processor 46 then compares the first and second concentrations to a reference value as above. The reference value is selected to be the concentration of the searched element in the overlapping or precision range of both equations (1) and (2). If the concentrations are below the reference value, a first concentration based on the output of the fluorescence detector 20 is used or selected to determine the concentration. If the concentrations are above the reference value, a second concentration based on the output of the transmitted radiation detector 21 is used or selected to determine the concentration. Selection of the appropriate concentration is represented by block 260. In this way, the most accurate concentration is used to determine the concentration of gold (or other metal). The appropriate equation is then used to calculate the element concentration (block 270). The concentration thus determined is then displayed by the processor 46 (block 275) and / or is appropriately recorded by the processor 46.

Finally, the processor 46 signals to the operator to inform whether further samples 12 with an unknown concentration of the wanted element will be tested (block 280). If the operator announces that additional samples 12 will be tested, the steps represented by blocks 200, 210, 220, 230, 232, 240, 250, 252, are repeated,

260. 270 and 275. This repetition continues until the operator notifies that no more specimens 12 will be tested. In this way, the concentrations of the wanted element in many specimens 12 can be accurately detected and the most accurate detection means can be selected by the processor 46 controlled by the program. that is, the detection of fluorescent radiation or transmitted radiation.

r15

Preferably, all the components of the preferred embodiment of the combination apparatus 11 are sufficiently small and lightweight so that they can be easily transported, for example, in a trailer, truck, van, hand luggage, and the like, thereby making the combination apparatus 11 portable and easy to transport to the area to be examined. soil or stone samples. In addition, the second embodiment advantageously eliminates the need for the use of optical fibers, thereby eliminating the problems associated with their use, such as cracking, while covering a greater overall range of accuracy using the fluorescence detector 20 and the transmitted radiation detector 21. Thus, by using the second embodiment of the invention, the advantages of the first guidance and other advantages are maximized and the disadvantages of the first embodiment are minimized.

In one embodiment of the invention, a device is provided that is small and light in weight and which is intended for transport in hand luggage. This small portable unit (hereinafter hand-held unit) is thus easily transported to the areas where various samples are analyzed. Advantageously, the handheld unit is battery powered, thereby allowing analysis in remote areas where other power sources are not readily available.

In order to preserve the limited energy of the hand-held battery, a reflector lamp is used as the radiant energy source 14 (Fig. 5) rather than a laser. The reflector lamp produces very short pulses or flashes of intense radiation, similar to flashes produced by the camera flash. These pulses or flashes of radiation are then optically filtered as needed to significantly suppress all wavelengths except the desired wavelength λ _ν (Of course, even a laser can emit pulses.)

5 and 6, the hand-held unit also utilizes three separate sensors or detectors.

The first sensor detects the intensity of radiation from the radiant energy source 14 (λ _η detector 15 from the source). The second sensor detects the intensity of radiation that fluoresces from the sample (λ ₂ , fluorescent radiation detector 20). The third sensor detects the intensity of radiation transmitted through the sample (λ /, transmitted radiation detector 21). Since the intensity of the radiant energy source 14 of a conventional reflector lamp 0 varies considerably from flash to flash, the use of a radiation detector from the source becomes to detect the intensity λ _ν thereby allowing reading of transmitted radiation λ / transmitted radiation detector 21 and fluorescent radiation λ _{2 by} detector 20 fluorescent radiation, extremely important for the successful operation of the handheld unit.

J

A conventional reflector lamp that can be used for the handheld unit is the XLS-542 reflector lamp, available from Xenon Corp.. of Wobum, Massachusetts. The weight of the handheld unit is less than about four kg (8 pounds), and its volume, including the battery, is no more than about 16000 cm ³ (1000 cubic inches). The reflector lamp is powered using a conventional power supply that increases the battery voltage (e.g., 9 volts) to a suitable working voltage of the reflector lamp (e.g., 600 volts). Preferably, the sensors have low power consumption and the processor 46, if used, can be a laptop or notebook.

The invention will now be described in more detail by specific non-limiting examples.

The general procedure for each analysis described below is as follows:

The samples are prepared with a view to obtaining representative ore samples. These samples are roasted in an oxidizing atmosphere at a temperature in the range of 600-800 ° C for one hour. Gold (Au) is leached by soaking the ore in a solution of potassium cyanide and potassium hydroxide in the presence of hydrogen peroxide. The cyanide extract is then acidified with hydrochloric acid in the presence of hydrogen peroxide at 90 ° C. The resulting AuCl / complex is separated from the interference ions by leaching with pre-prepared beads of poly (dibenzo 18-crown-6) in 0.6 M HCl. The polymer beads selectively capture the AuCl ₄ 'complex, leaving interference ions in HCl. After several washes, the AuCl ₄ * is regenerated by leaching the chains with captured AuCl ₄ 'acetone, the acetone is further evaporated in the presence of H ₂ O ₂ , leaving AuCl ₄ ' in HCl. AuCl ₄ 'is labeled with Rhodamine B dye. The dye complex and AuCl ₄ ' is further extracted into diisopropyl ether and its fluorescence and transfer ability is measured.

Example 1:

The range of gold concentrations (0, 100, 2000, and 20000 ppb) was investigated to determine the range of signals obtained by the method and apparatus of the invention as the amount of gold increases. The results in millivolts are shown in Table 1.

Table 1

Concentration of gold, ppb Milivolty 0 8 500 199 1 000 516 2 000 946 4 000 1 658 8 000 2 629

The results of Table 1 are plotted in Figure 4, which shows a regular non-linear response over a wide range of concentrations. These results demonstrate that the method and apparatus of the invention are applicable over a wide range of concentrations.

Example 2:

The method of the invention was used to determine the amount of gold present in two stone samples; these samples were labeled A and B, and were independently subjected to a heat test with results of 1325 ppb gold for sample A and 1660 ppb gold for sample B. The signals obtained for 0, 500, 100, 2000, and 4000 ppb gold were respectively 0, 410 , 770, 1430, and 2080 millivolts. When plotted, these values provide a regular non-linear response over the calculated range of concentrations.

The fluorescence signals for samples A and B were 970 and 1120 mV (after subtracting the values for the zero control sample), corresponding to 1325 and 1660 ppb gold, respectively.

Example 3:

A combination of a fluorometer and a transfer device as described above in connection with Fig. 5, Fig. 6, Fig. 7A and Fig. 7B was used to measure gold concentration in four samples labeled 1, 2 ", 3 and 4 containing ppb gold. 0, 100, 2000, and 20000. The results are shown in Table 2.

Table 2

The calculated ppb of the sample from their “measured values”

Calibration data ppb fluorescence (volts) transmission (volts 0 0.00346 1,711 100 ALIGN! 0,0341 1,678 2 000 0.402 1,333 20 000 0,676 0,0618 Calculated constants for the curve αΙ _ή TO al ₂ S _o T _o 0.000493 0,636 7.41 E-05 0.00346 1,711 Calculations of gold using equations (1) and (2) sample gold (ppb) S (volts) T (volts) gold (ppb) 1 0 0.00363 17 0.54 2 100 ALIGN! 0.345 1,681 101 3 2 000 0.401 1,337 1 990 4 20 000 0,686 0,0662 19615

It will be appreciated that the method and apparatus of the present invention will rapidly deliver results that are in good agreement with the values obtained by conventional analytical methods.

Claims (11)

PATENT CLAIMS _{75 lllA of L 00} i An apparatus for determining the content of an element in a solution of formulas j embedded in a cuvette, characterized in that oDs is lyophilized. means (14) for irradiating the sample solution with radiant energy in the first wavelength band; first detecting means (20) pcn-2 '' for detecting fluorescent radiant energy in the second wavelength band that is emitted from the sample solution under irradiation, wherein the second wavelength band does not contain any wavelength from the first wavelength band; a second detecting means (21) operable simultaneously with the first detecting means (20) for detecting the transmitted radiant energy in the first wavelength band which is transmitted by the sample solution under the influence of irradiation; and processing means (46) responsive to the first and second detection means for (a) automatically comparing the detected fluorescent energy and the detected transmitted energy, wherein the predetermined reference energy corresponds to a known concentration of the element in the reference solution; (b) selecting, based on this comparison, either the detected fluorescent radiant energy or the detected transmitted radiant energy as an indication of the concentration of the element in the sample solution; and (c) determining the concentration of the element based on the selected radiant energy. Apparatus according to claim 1, characterized in that 25 additionally comprises third detection means (15) for detecting the intensity of radiant energy in the first wavelength band; wherein the processing means (46) comprises means for correcting the detected radiant energy by the first and second detection means as a function of variations in radiant energy intensity 30 detected by the third detection means (15). The device of claim 1 or 2, wherein the radiation means (14) comprises a laser source (25) for generating radiant energy in a wavelength band of about 544 nm, and the first detection means (14). (20) include means for: - 5 detection of radiant energy in the wavelength band around 577 nm. Device according to claim 3, characterized in that the first detection means (20) comprise first filter means (35) for blocking radiant energy from an area outside the first zone 10, and the first photodetector (38) is optically coupled to radiation passing through the first filter means (35), the first photodetector (38) being adapted to generate a first output signal corresponding to the radiation intensity received by the first photodetector. The apparatus of claim 4, wherein the second detecting means (21) comprises second filter means (45) for blocking radiant energy from an area outside the second wavelength band, and the second photodetector (48) is optically coupled 20 of radiation passing through the second filter means (45), the second photodetector (48) being adapted to generate a second output signal corresponding to the intensity of the radiation received by the first photodetector. The apparatus of claim 5, wherein the processing means (46) comprises means for determining a first concentration of the element in the sample solution (12) and as a function of the first output signal; means for determining the second 5 the concentration of the element in the sample solution (12) as a function of the second output signal; means for determining a predetermined reference value as a function of the predetermined reference energy; and means for selecting either the first or second determined concentration as the measured concentration of the element in the sample solution 10 (12) comparing the first and second determined concentrations to a predetermined reference value, and selecting the first determined concentration as the selected concentration if the first and second determined concentrations are less than the predetermined reference value, and selecting the second determined concentration as the selected 15 concentration if the first and second determined concentrations are greater than a predetermined reference value. The device of claim 6, wherein the means for determining the first concentration comprises means 20 for calculating the equation C ₄ = (1 / l) ln [K / K - (S - S ₀₎ j, where C ₁ is the estimate of the first concentration, S is the first output signal, and K, Al and S _o are constants. Device according to claim 6, characterized in that: 25 means for determining a second concentration includes means for calculating the equation C ₂ = (1 / l) ln (T ₀ / T) where _C2 is the estimate of the second concentration, T is the second output signal, and T _o and al are constants. A method for determining the concentration of an element in a sample solution, comprising (a) irradiating (220) the sample solution (12) with incident radiation energy in a first wavelength band; (b) detecting (240) fluorescent radiant energy in the 5 a second wavelength band that is emitted from the sample solution (12) under irradiation, wherein the second wavelength band does not contain any wavelength from the first wavelength band; (c) detecting (250), coincident with the detection step (b), the transmitted radiant energy in the first wavelength band, 10 which is transferred by the sample solution (12) under irradiation; (d) determining a first measurement (270) of the element concentration in the sample solution (12) based on the detected fluorescent radiant energy, and determining a second measurement (270) of the element concentration in the solution W sample (12) based on detected transmitted radiation; and (e) 15 * selecting the first and second measurements as the selected element concentration measurement in the sample solution (12) by comparing the first and second measurements with a predetermined reference value that corresponds to a known element concentration in the reference solution. The method of claim 9, wherein the step (e) of selecting the first or second measurement as the selected element concentration measurement comprises selecting (260) the first concentration measurement as the selected concentration measurement if the first and second concentration measurements are less than predetermined. determined 25 reference value; and selecting (260) the second concentration measurement as the selected concentration measurement if the first and second concentration measurements are greater than a predetermined reference value. The method of claim 10, further comprising correcting (252) the detected fluorescent radiant energy and the detected transmitted radiant energy as a function of variations in the intensity of the incident radiant energy.