JP4986824B2 - Analytical method of high-frequency plasma mass spectrometer for trace precious metals - Google Patents

Description

  The present invention relates to an analysis method using a high-frequency plasma mass spectrometer for trace noble metals, and more particularly to a method for analyzing a trace noble metal in a sample containing a high matrix using a high-frequency plasma mass spectrometer.

In the smelting of non-ferrous metals such as copper, there is an increasing need for technological development for recovering valuable metals, particularly noble metals such as Au, Pt, Pd, Rh, Ru and Ir.
In determining the recovery method of precious metals, it is important to understand the behavior of precious metals in the smelting process, such as investigating the quantity balance of precious metals from the flash smelting furnace to the electrolytic cell, but the abundance is μg / g. It has been difficult so far because there are many cases below.
Therefore, a highly sensitive analysis method for precious metals is strongly demanded. In order to achieve the object, an analytical method with a lower limit of quantification of about 0.01 g / t (0.01 μg / g) is required.

As a microanalysis method for noble metals such as Au, a dry assay method and a tellurium coprecipitation method are known.
In the dry assay method, the sample is mixed with lead (II) oxide and a flux, and after preparing the molten sample, the crucible is melted, and precious metals such as gold are collected in the lead button and separated from other sample components. To do. Lead is soaked into bone ash by spraying a lead button, and only a precious metal is taken out and then quantified (Non-patent Document 1).
The tellurium coprecipitation method is a method in which tellurium is used as a carrier and a precious metal such as Au is selectively coprecipitated and separated from a hydrochloric acid solution by reduction of tin (II) chloride (Non-patent Document 2).
These methods are excellent in terms of decomposition of a large amount of sample, concentration separation from other components, and sensitivity.

  On the other hand, a high-frequency plasma mass spectrometer using inductively coupled plasma (ICP) or microwave induced plasma (MIP) is known as an apparatus for quantitatively analyzing trace elements with high sensitivity. The high-frequency plasma mass spectrometer ionizes the element to be measured contained in the solution sample by high-frequency plasma, introduces the generated ions into the mass spectrometer, and determines the ion mass at the mass / charge number (m / z) of the element to be measured. It is an apparatus for analyzing isotopes or elements by measuring the number. The high-frequency plasma mass spectrometer is capable of simultaneous multielement analysis with extremely high sensitivity and is suitable for trace element analysis.

  The high-frequency plasma mass spectrometer is designed to efficiently introduce ions generated in a high-frequency plasma at atmospheric pressure into an ionization unit equipped with a plasma torch that ionizes the element to be measured with high-frequency plasma. From the interface unit equipped with the differentially evacuated sampling cone and skimmer cone, the ion lens unit for efficiently extracting ions from the plasma and leading them to the mass separation unit, and the mass analysis unit for mass analysis of the generated ions Mainly configured (Non-patent Document 3).

Japanese Industrial Standard M8111 “Method for quantifying gold and silver in ore” Toyoguchi et al., “Quantification of gold in ores by atomic absorption spectrometry”, Analytical Chemistry, Japan Analytical Chemical Society, Vol. 16, 1965, p565 Japanese Industrial Standard K0133 “General Rules for High Frequency Plasma Mass Spectrometry”

  In order to make the best use of the performance of the high-frequency plasma mass spectrometer, it is desirable to separate a precious metal such as Au from the sample by a method such as a dry assay method or a tellurium coprecipitation method and then introduce it into the analyzer. However, a method that requires a step of separating a noble metal such as Au from a sample is not suitable for a continuous test that requires quick analysis because the separation operation is complicated and analysis time is required.

  Accordingly, an object of the present invention is to provide a method for analyzing a trace amount of noble metals such as Au with high frequency plasma mass spectrometry without performing a prior separation operation. Moreover, this invention makes it another subject to provide the analyzer for implementing such an analysis method.

  The present inventor has encountered several problems in solving the above problems.

  In the smelting of non-ferrous metals such as copper, samples that are subject to precious metal analysis are hardly soluble, and acid decomposition is often not applicable. Therefore, in the case of a solid sample, in order to make it into a complete solution in the pretreatment, the alkali melting method is mainly used, and a sample solution containing a high matrix is introduced into the analyzer. The “matrix” here refers to sodium salt used for melting, copper derived from a sample, iron, and the like.

  However, when a solution containing a high matrix is introduced into the analyzer, interference may occur. Interference includes spectral interference and non-spectral interference. For spectral interference, by using the alkali melting method as a sample pretreatment, the amount of sodium used in the pretreatment is overwhelmingly higher in the sample solution than copper, iron, or the like derived from the sample. Therefore, the ratio of the influence on the spectral interference of noble metals such as gold in the measurement is suppressed. Therefore, it is considered that there is no problem in the determination of a noble metal such as a small amount of Au having a large mass number. On the other hand, for non-spectral interference, the matrix effect that reduces the strength and stability of noble metals such as gold due to the matrix contained in the sample has been a problem.

  When using a high-frequency plasma mass spectrometer under the normal measurement conditions recommended by the manufacturer, to avoid the matrix effect, the total matrix concentration that can be directly introduced into the analyzer without any separation operation is about 0.1% at the maximum. In order to obtain high detection intensity, it was necessary to limit to about 0.01%. For this reason, it is conceivable to dilute the sample solution to a measurable concentration and measure the total matrix concentration by introducing a small amount of sample using flow injection. The problem remains.

  Therefore, the present inventor has examined various measurement conditions that can suppress the matrix effect even if a solution containing a high matrix is introduced into the high-frequency plasma mass spectrometer. It was found that the maximum measurement conditions were large, and that this occurred due to ion collision between the interface part and the first stage ion lens. Then, it was found that the matrix effect is significantly reduced by operating the high-frequency plasma mass spectrometer without applying voltage to the first-stage ion lens through which the sample exiting the interface portion first passes.

The present invention, which has been completed based on the above findings, is in one aspect,
Preparing a sample containing 500 to 5,000 ppm by weight N a,
Analyzing the noble metal in the sample with a high-frequency plasma mass spectrometer having an interface part having a skimmer cone and an ion lens part having a three-stage ion lens,
The sensitivity is adjusted by applying an applied voltage to the first-stage ion lens closest to the interface unit to 0 V and applying the second-stage and third-stage applied voltages , and the skimmer cone has an inner wall in a cross section. The shape is a pentagonal shape with the sample incident point at the apex, and this pentagonal shape is symmetric with respect to the axis perpendicular to the base from the apex, the apex angle is 80 to 130 °, the base angle is 60 to 80 °, the orifice diameter Is 0.35-0.45 mmΦ,
A method for analyzing a noble metal contained in a sample, wherein the lower limit of measurement is 0.01 g / t .

In one embodiment of the analysis method according to the present invention, the sample is a liquid sample composed of a leachate obtained by leaching ore with an acid containing a sodium salt.

In one embodiment of the analysis method according to the present invention, the sample is obtained by subjecting a solid sample comprising a leaching residue obtained by leaching ore to an acid containing a sodium salt by an alkali melting method using a sodium compound. It is obtained by processing.

  In still another embodiment of the analysis method according to the present invention, the noble metal is Au.

  In another embodiment of the analysis method according to the present invention, Lu is used as an internal standard element when Au is analyzed, and quantified by the internal standard method.

  In another embodiment of the analysis method according to the present invention, the Na concentration in the liquid sample or sample solution is 1000 to 4000 mass ppm.

  In still another embodiment of the analysis method according to the present invention, the concentration of each noble metal to be measured in the sample is 100 mass ppm or less.

  In still another embodiment of the analysis method according to the present invention, the high-frequency plasma mass spectrometer is an ICP mass spectrometer.

  In another aspect of the present invention, the skimmer cone includes an interface portion having a skimmer cone and an ion lens portion having a three-stage ion lens, and the skimmer cone has a pentagonal shape in which the inner wall shape in the cross section is a sample incident point as a vertex, This pentagonal shape is symmetric with respect to the axis perpendicular to the base from the apex, the apex angle is 110 to 130 °, the base angle is 40 to 50 °, the orifice diameter is 0.35 to 0.45 mmΦ, This is a high-frequency plasma mass spectrometer for carrying out the above analysis method, in which the voltage applied to the nearest first-stage ion lens can be set to 0V.

  According to the present invention, it is possible to analyze a small amount of noble metal with high accuracy by a high-frequency plasma mass spectrometer without performing a prior separation operation. Therefore, it is possible to quickly analyze a trace amount of noble metal as compared with the conventional case.

Target Sample A sample to be analyzed by the present invention is a sample containing a noble metal. In particular, the present invention is intended for liquid and solid samples containing trace amounts of noble metals, generally no more than 100 ppm by weight, especially no more than 1 ppm by weight. The liquid sample is typically a leachate that is generated when ore (eg, copper ore) is leached with an acid containing a high sodium salt, and the solid sample is ore (eg, copper ore) containing high sodium. The leaching residue generated when leaching with an acid containing a salt is typical. Examples of the solid sample include intermediate products and dust, automobile waste catalyst, precious metal scrap, and intermediate products generated from these recovery processes in the copper smelting process such as copper concentrate, copper calami (slag) and copper mat.
In the present invention, “noble metal” refers to gold (Au), silver (Ag), and platinum group (Ru, Rh, Pd, Os, Ir, Pt). The present invention is particularly suitable for the analysis of Au.
Therefore, in a typical embodiment of the analysis method according to the present invention, the concentration of each noble metal in the sample is 100 ppm by mass or less, more typically 1 ppm by mass or less, for example, from 0 to 100 ppm by mass. is there.

In order to introduce the pretreated solid sample into the high-frequency plasma mass spectrometer, it is necessary to dissolve at least the element to be measured, but the noble metal that is the measurement target is hardly soluble and hardly soluble in mineral acids. It is dissolved by an alkali melting method using sodium compounds such as sodium oxide, sodium nitrate, sodium peroxide, sodium carbonate. Although this method is generally performed and need not be explained in particular, the pretreatment procedure by the alkali melting method is illustrated in FIG.

  First, a mixed flux of sodium compound (eg, sodium carbonate and sodium peroxide) is mixed with a sample placed in a metal (eg, alumina) crucible, and the mixture is mixed with sodium peroxide to prevent the sample from splashing. The crucible containing the mixture is heated with a gas burner (eg, Bunsen burner) or an electric furnace to melt the noble metal in the sample. Thereafter, the obtained melt is transferred to a beaker, and water is added to leaching by heating. After standing to cool, add hydrochloric acid and dissolve again by heating. Add water to make the volume constant. Thereafter, a predetermined amount is taken, and an internal standard element (eg, Lu solution) is added as necessary to make a constant volume.

  The pretreated solution sample is made to contain about 500 to 5000 ppm by mass of Na. If the Na concentration is too low by diluting the solution sample, the concentration of noble metals to be measured in the solution sample will also be lowered and the analysis accuracy will be reduced. This is because it is not desirable to concentrate the Na concentration too high. For these reasons, it is preferable that Na be included in the pre-treated solution sample in an amount of about 1000 to 4000 mass ppm, and more preferably about 2000 to 3000 mass ppm.

  On the other hand, no pretreatment is necessary for the liquid sample. However, since the object of the present invention is to suppress the matrix effect of a sample solution containing a high sodium salt (high matrix), the liquid sample has a concentration as described above, that is, about 500 to 5000 mass ppm, preferably Is a liquid sample containing about 1000 to 4000 ppm by mass, more preferably about 2000 to 3000 ppm by mass of Na. Such a sample is typically a leachate generated when an ore (eg, copper ore) is leached with an acid containing a high sodium salt.

  FIG. 2 shows an example of a sample preparation procedure for introducing the leachate into the analyzer. First, in order to stabilize noble metals such as Au in the sample, hydrochloric acid is added, and then water is added to make a constant volume. Thereafter, a predetermined amount is taken, and an internal standard element (eg, Lu solution) is added as necessary to make a constant volume.

High-frequency plasma mass spectrometer A sample solution obtained by pre-processing and dissolving a liquid sample or a solid sample is analyzed by a high-frequency plasma mass spectrometer in accordance with JIS K0133. As the high-frequency plasma mass spectrometer, either an inductively coupled plasma (ICP) mass spectrometer or a microwave induction plasma (MIP) mass spectrometer may be used.
The configuration of the high-frequency plasma mass spectrometer used in the present invention is general except for some configurations. (A) An ionization source (high-frequency plasma: ICP or MIP) for decomposing a sample into atoms and further exciting and ionizing it, a power source for maintaining this, and an ionization unit having a control circuit thereof; A boundary was formed between the plasma under atmospheric pressure and the vacuum mass separator, and differential evacuation was performed to efficiently introduce ions generated in the high-frequency plasma under atmospheric pressure into the mass analyzer under high vacuum. Interface part with sampling cone and skimmer cone, (c) A part for efficiently extracting ions from the plasma and guiding them to the mass separation part. Ion lens (extraction electrode), particle and photon shielding device, focusing electrode Ion lens unit, (d) Ion ions from the ion lens unit, for each mass using the electromagnetic field action on the ions in the vacuum Comprising a mass separation unit for between and space separated. In addition, a detection unit, a gas control unit, a vacuum exhaust unit, a system control unit, and a data output unit are also provided.

  Of the configuration of the high-frequency plasma mass spectrometer used in the present invention, the characteristic part is the configuration of the ion lens unit and its operating conditions. The ion lens includes an electric field type and a magnetic field type. In the present invention, the electric field type is used. The electric field type ion lens includes a circular hole lens, a cylindrical lens, and an Einzel lens. The circular hole lens type is used in the present invention. The ion drawing lens is composed of three stages, and the analyzer is operated with the applied voltage to the first stage ion lens closest to the interface unit being 0V. Although it is not intended that the present invention be limited by theory, in this way, contamination of the ion lens system in the second and subsequent stages even when a main component (eg, sodium, copper, iron, etc.) is introduced. In other words, since the convergence for drawing ions from the first stage is alleviated, the adhesion of the main component to the second and third stage ion lenses is reduced. It can be expected that it can be supplied to the second and third stage ion lenses, and a decrease in sensitivity during measurement can be suppressed.

  The voltage condition to be applied to the second and third stage ion lenses is that the voltage applied to the first stage ion lens is set to 0 V, and the second and third stage application is performed while monitoring the sensitivity to the element to be measured. It can be optimized by adjusting the voltage. In one embodiment of the present invention, in particular, the voltage applied to the second stage ion lens is −1 to −50 V, and the voltage applied to the third stage ion lens is −150 to −450 V.

  Other measurement conditions may follow the manual of a commercially available high-frequency plasma mass spectrometer.

  By analyzing with the above configuration and measurement conditions, a lower limit of quantification of 0.01 mg / L or less can be obtained for a liquid sample (for example, the above-described leachate), and a lower limit of quantification of about 0.1 g / t can be obtained for a solid sample. Obtainable. However, since the voltage condition of the ion lens used in the present invention is greatly different from the normal condition, there is an aspect that a high signal-to-background ratio (S / B ratio) cannot be obtained. Can be lowered.

  A means for increasing the S / B ratio includes changing the shape of the skimmer cone. The skimmer cone is generally in the shape of a triangular pyramid, and the inner wall shape in the cross section is an isosceles triangle shape with the sample incident point as the apex, generally the apex angle is 55 to 65 °, and the orifice diameter is 0.3. ˜1 mmΦ (see FIG. 4 left). However, as the shape of the skimmer cone, the lower limit of quantification is reduced by changing the inner wall shape in the cross section to a pentagonal shape (refer to the right in FIG. 4) that is symmetric with respect to the axis perpendicular to the base from the vertex. Can be lowered. Thus, by changing the inner wall shape of the skimmer cone, the lower limit of quantification can be lowered because the apex angle of the skimmer cone is expanded and the collision with the “space charge region”, which is the region where ions are drawn. Can be expected to be suppressed. Although theoretical elucidation from the viewpoint of ion motion has not yet been made, the effect is that suppression of the spectrum interference of molecular ions caused by argon is high and the background on the high mass side is reduced. Therefore, it is effective in achieving the target lower limit of quantification of noble metals such as a trace amount Au having a large mass number. In the present invention, a conventional skimmer cone whose inner wall shape is an isosceles triangle is referred to as a “standard skimmer cone”, and a pentagonal skimmer cone according to the present invention is referred to as a “D skimmer cone”.

Specifically, as the pentagonal shape of the inner wall, the apex angle may be 80 to 130 °, the base angle may be 60 to 80 °, and the orifice diameter may be 0.35 to 0.45 mmΦ. Typically, the apex angle is 90 to 110 °, the base angle is 60 to 70 °, and the orifice diameter is 0.35 to 0.45 mmΦ.
The outer wall shape in the cross section of the D-type skimmer cone is generally a pentagon shape reflecting the shape of the inner surface. In general, the thickness is preferably about 0.1 to 0.6 mm. In order to efficiently draw the target ions into a high vacuum region, the wall thickness is generally made thinner as it approaches the apex, and the tip is generally made an acute angle. Therefore, for the pentagonal shape of the outer wall, the apex angle is larger than the apex angle of the inner wall, typically 110-130 °. The base angle is typically 40-50 °.

By using the D-type skimmer cone, the lower limit of measurement can be set to 0.01 g / t for both the liquid sample and the solid sample.

  Examples of the quantitative analysis method include a calibration curve method, an internal standard method, and a standard addition method, and any of them may be used. However, it has been found that, in analyzing noble metals contained in copper ore, especially Au, it is possible to analyze with high accuracy by analyzing by an internal standard method using Lu as an internal standard element. Lu is desirable in that it is not contained in copper ore, and the ionization energy value and mass number are close to Au.

  Hereinafter, examples will be described so that the present invention and its advantages can be better understood, but the present invention is not limited to these examples.

Example 1: Suppression of matrix effect by adjusting ion lens voltage A change in gold intensity detected by an ICP mass spectrometer (model SPQ9400 manufactured by SII Nanotechnology Co., Ltd.) containing aqueous solutions with different sodium concentrations containing 1 mass ppb of gold. I saw. The measurement conditions were the manufacturer recommended conditions (normal conditions) and the conditions according to the present invention (invention conditions) (Table 1). The manufacturer's recommended conditions are the measurement conditions that maximize the ion transmission efficiency of the target quantitative element.

  FIG. 5 shows the results of normal conditions and FIG. 6 shows the results of invention conditions for the relative strength when the gold strength when the sodium concentration is 0.01% by mass is 1. It can be seen that the gold strength decreased as the sodium concentration increased under normal conditions, whereas the gold strength did not decrease even when 0.3% by mass of sodium concentration was added under the inventive conditions. Therefore, it can be seen that the matrix effect is easily affected by measurement conditions that maximize the ion transmission efficiency of the target quantitative element, and occurs between the interface portion and the first-stage ion lens.

Example 2: Suppression of the effect of the matrix effect on the slope of the calibration curve Gold solution containing no sodium salt (single product) and gold solution containing 0.3% by mass of sodium salt (sodium salt) The change in gold strength detected by an ICP mass spectrometer (model SPQ9400 manufactured by SII Nanotechnology Co., Ltd.) was observed when V was changed to 0 μg / L, 0.5 μg / L, 1 μg / L, and 5 μg / L. As in Example 1, the measurement conditions were the manufacturer recommended conditions (normal conditions) and the conditions according to the present invention (invention conditions).

  As a result, it was found that, under normal conditions, the strength of gold decreased due to the matrix effect and the slope of the calibration curve decreased as shown in FIG. On the other hand, under the inventive conditions, as shown in FIG. 8, the slopes of the calibration curves are almost the same regardless of the presence or absence of the sodium salt, and it was found that the matrix effect can be suppressed.

Example 3: Determination of an element suitable as an internal standard element Each of aqueous solutions having different sodium salt concentrations containing 1 mass ppb of Au, Y, Gd, Tm, Lu, or Tl was prepared, and an ICP mass spectrometer (manufactured by SII Nanotechnology Co., Ltd.) Changes in element strength detected by model SPQ9400) were observed. The measurement conditions are the same as the invention conditions of Example 1. The results are shown in FIG. 9 for the relative strength when the strength of each element is 1 when the sodium concentration is 0.01 mass%. As a result, it can be seen that the intensity changes of lutetium and gold are almost the same. Moreover, even if it is invention conditions, it turns out that the intensity | strength fell under the influence of the matrix effect from the sodium concentration exceeding 0.3 mass%.

Example 4: Suppression of Matrix Effect on Real Sample The actual sample contains matrix components other than sodium. Therefore, a calibration curve of gold in the sample was prepared by the internal standard method using Lu as the internal standard element. The measurement conditions are the same as the invention conditions of Example 1. Calibration curves were leached from an aqueous solution of gold containing no sodium (single product), an aqueous solution of gold containing 0.3% by weight of sodium (sodium salt), and an acid containing high sodium salt from ore (eg, copper ore). A leaching solution (containing 0.2% by mass of sodium) was prepared. All gold concentrations in the samples were used. The results are shown in FIG. From the figure, it can be seen that the slope of the gold calibration curve in the actual sample is almost the same as that of the single product or sodium salt. This shows that the matrix effect is suppressed by the analysis method of the present invention even in the actual sample.

Example 5: Improving sensitivity by changing the shape of the skimmer cone Under the inventive conditions of Example 1, the shape of the skimmer cone is a general triangular pyramid shape (vertical angle 60 °, orifice diameter 0.4 mmΦ). When the inventive conditions of Example 1 were used, the detection limit and the lower limit of quantification were determined from the background equivalent concentration (hereinafter referred to as “BEC value”) of the blank test for an aqueous solution of gold containing 0.3% by mass of sodium. The results are shown in Table 2. As a result, it was found that the lower limit of quantification of the trace amount gold in the leachate can achieve the lower limit of quantification of 0.01 mg / L. On the other hand, although it was not possible to obtain a lower limit of quantification of 0.01 g / t in a solid sample such as ore, it was found that the determination of a trace amount of gold up to the lower limit of quantification of 0.1 g / t is sufficiently possible.

The shape of the skimmer cone is D type (inner wall: apex angle 90-100 °, base angle 60-70 °, outer wall: apex angle 110-130 °, base angle 40-50 °, orifice diameter 0.35. ～0.45Mmfai; instead of reference 1 2), Table 3 shows the result of obtaining the detection limit and the lower limit of quantitation from the previous as well as BEC value. As a result, it was found that the lower limit of quantification of 0.01 g / t can be achieved for the solid sample.

Example 6: Verification of measurement accuracy The reference materials (copper concentrate and platinum ore) were pretreated as shown in FIG. 1, and the shape of the skimmer cone was changed to the D type used in Example 5, and then Example 1 Under the present invention conditions, the concentration of gold contained in these was analyzed. The results are shown in Table 4. The quantitative result of the trace amount of gold in the standard substance was in good agreement with the certified value, and it was verified that the measurement accuracy was high.

Example 7: Comparison with the dry assay method About 52 lots of leach residue continuously discharged by the treatment from the hydrometallurgical technique are included in the residue in each of the method according to the present invention and the dry assay method. Gold concentration was analyzed. As a method according to the present invention, the pretreatment described in FIG. 1 was performed, and the shape of the skimmer cone was changed to the D type used in Example 5, and then ICP mass spectrometry was performed under the inventive conditions of Example 1. The measurement results were in good agreement with the method according to the present invention and the dry assay method (FIG. 11).

Example 8: Comparison with tellurium coprecipitation method For four types of leachates A to D obtained when a copper ore was leached using an acid containing a high sodium salt, the method according to the present invention and the tellurium coprecipitation method The gold concentration contained in the sample was analyzed by each of the methods. As a method according to the present invention, the pretreatment described in FIG. 1 was performed, and the shape of the skimmer cone was changed to the D type used in Example 5, and then ICP mass spectrometry was performed under the inventive conditions of Example 1. The results are shown in Table 5. The measurement results agreed well with the method according to the present invention and the tellurium coprecipitation method.

Example 9: Repeatability accuracy of the same sample Table 6 shows the average value and standard deviation of the gold concentration when the sample D was analyzed 8 times by the method of the present invention in Example 8. It can be seen that the analysis method according to the present invention has high reproducibility of the measurement results.

It is a figure which illustrates the pre-processing procedure of the solid sample by an alkali melting method. It is a figure which illustrates the adjustment procedure of a liquid sample. It is a schematic sectional drawing of the interface part and ion lens part of a high frequency plasma mass spectrometer. It is a schematic sectional drawing of the skimmer cone of a high frequency plasma mass spectrometer. The left side is a standard skimmer cone, and the right side is a D type skimmer cone. It is a figure which shows the change of gold intensity | strength when changing the sodium concentration in a sample on normal conditions. It is a figure which shows the change of gold intensity | strength when changing the sodium concentration in a sample on invention conditions. It is a figure which shows the inclination of the gold | metal calibration curve in a normal condition. It is a figure which shows the inclination of the gold | metal calibration curve in invention conditions. It is a figure which shows the change of the intensity | strength of gold | metal | money and an internal standard element when changing the sodium concentration in a sample in invention conditions. It is a figure which shows the inclination of the calibration curve of gold | metal | money with respect to a single item, a sodium salt, and a real sample when Lu is used as an internal standard element. It is a figure which shows the comparison of an analytical value about the case of the method of this invention, and a dry-type assay method. It is a figure which shows the shape of the D-type skimmer cone used in the Example.

Explanation of symbols

1 Torch 2 Sampling cone 3 Skimmer cone 4 First stage ion lens 5 Second stage ion lens 6 Third stage ion lens 11 Vertical angle 12 Vertical angle 13 Base angle

Claims (8)

Leached the ore with acid containing sodium salt, a step of preparing a sample containing 500 to 5,000 ppm by weight Na,
Analyzing the noble metal in the sample with a high-frequency plasma mass spectrometer having an interface part having a skimmer cone and an ion lens part having a three-stage ion lens,
The sensitivity is adjusted by applying an applied voltage to the first-stage ion lens closest to the interface unit to 0 V and applying the second-stage and third-stage applied voltages, and the skimmer cone has an inner wall in a cross section. The shape is a pentagonal shape with the sample incident point at the apex, and this pentagonal shape is symmetric with respect to the axis perpendicular to the base from the apex, the apex angle is 80 to 130 °, the base angle is 60 to 80 °, the orifice diameter Is 0.35-0.45 mmΦ,
The measurement lower limit is 0.01 g / t.
A method for analyzing a noble metal contained in a sample . The solid sample consisting of leach residue obtained by leaching the ore in containing sodium acid pretreated by alkali fusion method using a sodium compound, to prepare a sample containing 500 to 5,000 ppm by weight of Na Process,
Analyzing the noble metal in the sample with a high-frequency plasma mass spectrometer having an interface part having a skimmer cone and an ion lens part having a three-stage ion lens,
The sensitivity is adjusted by applying an applied voltage to the first-stage ion lens closest to the interface unit to 0 V and applying the second-stage and third-stage applied voltages, and the skimmer cone has an inner wall in a cross section. The shape is a pentagonal shape with the sample incident point at the apex, and this pentagonal shape is symmetric with respect to the axis perpendicular to the base from the apex, the apex angle is 80 to 130 °, the base angle is 60 to 80 °, the orifice diameter Is 0.35-0.45 mmΦ,
The measurement lower limit is 0.01 g / t.
A method for analyzing a noble metal contained in a sample . The analysis method according to claim 1 or 2 , wherein the noble metal is Au. The analysis method according to claim 3 , wherein Lu is used as the internal standard element, and quantification is performed by the internal standard method. The analysis method according to any one of claims 1 to 4 , wherein the Na concentration in the liquid sample or the sample solution is 1000 to 4000 ppm by mass. The analysis method according to any one of claims 1 to 5 , wherein the concentration of each noble metal to be measured in the sample is 100 mass ppm or less. The method for analyzing high-frequency plasma mass spectrometer according to claim 1 to 6 or one claim is ICP mass spectrometer. Equipped with an interface part having a skimmer cone and an ion lens part having a three-stage ion lens, the inner wall shape in the cross section is a pentagonal shape with the sample incident point at the apex, and this pentagonal shape is perpendicular to the base from the apex. The vertical angle is 110 to 130 °, the base angle is 40 to 50 °, the orifice diameter is 0.35 to 0.45 mmΦ, and the first-stage ion lens closest to the interface is high-frequency plasma mass spectrometer for carrying out the analytical method of the applied voltage can be set to 0V claim 1-7 any one claim.