JP4185066B2 - Sample pretreatment method and method for measuring mercury content in sample - Google Patents

Description

  The present invention relates to a sample pretreatment method for quantifying harmful elements, particularly mercury (Hg), present in a sample containing a resin material such as plastic, and a method for measuring the amount of mercury in the sample.

  Recently, laws and regulations focusing on the harmfulness of chemical substances are being developed in various countries around the world.European Union has enacted the RoHS (Restriction of Hazardous Substances) Directive, which is a restriction on the use of specific substances since 2006 It is obliged to exclude six environmentally hazardous substances such as lead (Pb) and mercury (Hg) from electrical and electronic equipment products. These directives are also applicable to companies that export electrical and electronic equipment products to Europe in addition to manufacturers, and accurately grasp the abundance of environmentally hazardous substances in electrical and electronic equipment products and prove that they are not contained. It has become a serious responsibility for the company.

  Conventionally, official methods have been promulgated as methods for measuring Pb and Cd, which are environmentally hazardous substances. For example, BSEN-1122 (2001) (Determination of Cadmium wet decomposition method), the official European method, and EPA method B (EPA SW-846 Method 3050B Acid digestion of sediments, sludge, and sludge, and the US Environmental Protection Agency) It is necessary to measure each element individually using soils). Basically, this is a wet acid decomposition method in which an oxidizing acid such as nitric acid, hydrochloric acid, sulfuric acid, or hydrogen peroxide solution is added to the sample to decompose the inorganic or organic substances as the matrix. In general, measurement is performed by a method or an atomic absorption method (see, for example, Patent Document 1).

Also, in ISO6101-2 Rubber- Determination of metal content by atomic absorption spectrometry-, an ashing method using a platinum crucible is proposed as a lead determination method.
However, these official methods target Pb and Cd, and are not examples of methods for quantifying Hg at the same time. And, when trying to quantify Hg by the above-described quantification method for Pb and Cd, the following problems arise.

  That is, the wet acid decomposition method has a problem that Hg is vaporized and volatilized, resulting in an inaccurate quantitative result. In addition, in the wet acid decomposition method, in order to increase the reaction effect using a watch glass, acid vapor adheres as droplets to the watch glass, and when it falls, it reacts with a high-temperature acid solution. Causes volatilization of Hg and contributes to inaccurate quantitative results. Furthermore, since Hg has a property of being easily adsorbed on the solid surface, when it is used as an aqueous solution, it is adsorbed on the wall surface of glass or chemical resin, which contributes to inaccurate quantitative results.

  On the other hand, in the ashing method using a platinum crucible, Hg loss due to rapid heating, especially in chemical resins, there are cases where a lot of chlorine (Cl) is added, and it is easy to volatilize as chloride, so quantitative determination There is a problem of inaccurate results.

Conventionally, Hg, which tends to volatilize, can be quantified independently by using a closed-type microwave decomposition apparatus, heat vaporization (-gold amalgam trap) -atomic absorption spectrometry, or in the presence of potassium permanganate, sulfuric acid + A method is known in which after acid decomposition with nitric acid, potassium peroxodisulfate is added, reduced with hydroxylamine hydrochloride Mn, and then measured by atomic absorption. However, these methods require a problem of requiring an expensive microwave decomposing apparatus, and a large amount of potassium permanganate (for example, 20 to 30 times equivalent to the amount of mercury). Is inaccurate.
JP 2004-271229 A

  As described above, it is difficult to accurately determine Hg with the conventional official method. In addition, the conventional Hg determination method quantifies Hg alone, which requires an expensive microwave decomposing device, and because a large amount of potassium permanganate is used, the Hg determination result is inaccurate. There is a problem of becoming.

  The present invention has been made in response to such a conventional situation, and a sample pretreatment method and a method for measuring the amount of mercury in a sample capable of measuring the mercury content in a sample more easily and accurately than in the past. Is to provide.

  According to one aspect of the present invention, there is provided a sample pretreatment method for measuring the amount of mercury in a sample containing a resin material, comprising platinum, gold, silver, ruthenium, rhodium, palladium, osmium, and iridium. A pre-sample comprising: a decomposition step of adding at least one and decomposing the sample with an acid in a solution; and an organic substance removal step of removing organic substances in the sample after the decomposition step A processing method is provided.

  According to another aspect of the present invention, there is provided a method for measuring an amount of mercury in a sample for measuring an amount of mercury in a sample containing a resin material, comprising platinum, gold, silver, ruthenium, rhodium, palladium, osmium, iridium. A decomposition step of decomposing the sample with an acid in a solution, an organic substance removal step of removing organic substances in the sample after the decomposition step, and after the organic substance removal step, There is provided a method for measuring the amount of mercury in a sample, comprising a quantitative step for quantifying mercury in the sample.

  As a result of intensive studies to solve the above-mentioned conventional problems, the present inventors, as a result, in general open acid decomposition method, platinum, gold, silver, ruthenium, rhodium, palladium, osmium, By coexisting at least one element of iridium, it has been found that Hg in chemical resin materials that are problematic due to RoHS regulations, etc. can be measured easily and safely with high accuracy. is there.

  Conventionally, mercury easily forms amalgam with gold, silver, etc., and this reaction has been used as a collector for that purpose. However, when mercury coexists with gold, silver, etc. in an aqueous solution, it is ionized compared to these. Since mercury, which has a large tendency, exists as ions, it has been confirmed that even in sudden chemical reactions during acid decomposition, it can exist as stable ions and volatilization is suppressed.

  In addition, the present inventors have also found that there is a double effect of preventing volatilization by the formation of a solid solution with gold or silver, etc., compared with the melting point of mercury alone, even at the time of high-temperature treatment during the subsequent decomposition of organic matter. Thus, in order to prevent the volatilization of mercury and the prevention of adsorption, a sample pretreatment in which an element having a low ionization tendency (at least one element of platinum, gold, silver, ruthenium, rhodium, palladium, osmium, iridium) is added in advance. The mercury can be easily and accurately quantified by the method and the method for measuring the amount of mercury in a sample.

  In the decomposition step, the upper opening of the container containing the solution is covered with a lid whose lower surface is inclined in one direction and inclined toward the side wall of the container. Thus, bumping due to a sudden drop of droplets can be prevented, and the recovery rate of elements other than mercury can be improved.

  According to the present invention, it is possible to provide a sample pretreatment method and a method for measuring the amount of mercury in a sample, which can measure the mercury content in a sample more easily and accurately than in the past.

  Hereinafter, the details of the present invention will be described with reference to the drawings.

  FIG. 1 shows the steps of a sample pretreatment method and a method for measuring the amount of mercury in a sample according to this embodiment. As shown in the figure, in this embodiment, first, in a solution containing at least one of platinum, gold, silver, ruthenium, rhodium, palladium, osmium, iridium and containing these metal ions. Then, a decomposition step of decomposing the sample containing the resin material with an acid is performed (101).

  In this decomposition step, as shown in FIG. 2, a predetermined amount (for example, 0.2 g) of a sample made of a resin material is accommodated in the container 1, and a predetermined amount (for example, 10 μg / ml) of gold or the like is added. A solution obtained by adding an acid such as sulfuric acid or nitric acid to pure water and reacting gently with an acid at a relatively low temperature, for example, about 100 ° C. At this time, the opening of the container 1 is not the watch glass 12 shown in FIG. 4 in which the conventional lower surface is convex, but the lower surface is in one direction and the side wall of the container 1 as shown in FIG. By reacting with the cover 2 covered with an inclined surface (inclination angle of about 30 °, for example) inclined toward the surface, droplets adhering to the cover 2 are prevented from suddenly dropping, and mercury is caused by bumping. And other elements can be prevented from volatilizing.

  The material of the container 1 is, for example, glassy carbon having a surface roughness of 10 μmRa or less, thereby reducing contamination from the container 1 and reducing the amount of adsorption of mercury or the like on the wall surface of the container 1. Can do.

  After the organic matter in the sample is changed to black by the decomposition step, the temperature is raised, and an organic matter removal step of decomposing and removing the organic matter is performed, for example, at around 450 ° C. (102). At this point, since mercury exists as ions in the solution, it is stably present in the solution even if kept at a high temperature. Further, by heating at 450 ° C., the organic substance is separated as carbon dioxide, and the main component can be removed.

  Through the above steps, the sample pretreatment step is completed. Thereafter, a quantitative process for quantitatively determining mercury in the sample is performed (103). In this determination step, for example, an inductively coupled plasma mass spectrometer is used. This inductively coupled plasma mass spectrometer is a technique that uses plasma generated by high frequency electromagnetic waves for excitation of atoms, and has the feature that it can measure multiple elements simultaneously and with high sensitivity. This inductively coupled plasma mass spectrometer is composed of a plasma torch, a mass analysis part, and a detector, and the sample is transferred in the apparatus by a carrier gas such as Ar.

  The sample pretreatment method and the mercury content measurement method in the present invention are not particularly limited with respect to the resin material in the sample. Specifically, for example, plastics such as PE, PVC, and ABS, synthetic rubber, paint components, and the like can be targeted. In addition to mercury, other elements such as lead, cadmium, and chromium can be simultaneously determined as mercury. Further, the presence state may be either solid or liquid.

  Further, when the electronic component material is used as a measurement sample, for example, organic compounds such as printed circuit boards, FPCs, and packaging materials, and reagents, jigs, and packaging used for forming these are also targets. .

  As described above, since the method of the present invention can eliminate various disturbances during pretreatment such as volatilization and adsorption, the object is not particularly limited, and resins and other materials used in all manufacturing processes and their production Applicable to process.

  Hereinafter, the present invention will be described in more detail by way of examples and comparative examples related to the present invention.

(Example 1) Quantification of heavy metal elements in chemical resin European standard materials (BCR-680, BCR-681) with guaranteed measurement values were prepared as samples. Using a decomposition vessel shown in FIG. 1, 0.2 g of a sample was placed, 10 μg of Au was added, and decomposition was performed at a temperature of 100 ° C. with a solution of 5 ml of sulfuric acid and 10 ml of nitric acid.

  After decomposition, sulfuric acid and organic substances were removed at 450 ° C.

After cooling, 5 ml of nitric acid was added to dissolve the residue, and measurement and analysis were performed with an inductively coupled plasma mass spectrometer (SPQ9000 manufactured by Seiko Denshi Kogyo Co., Ltd.) with a high frequency output set to 1.1 kW. The sample solution was introduced into the inductively coupled plasma mass spectrometer using a coaxial quartz nebulizer. The measurement mass numbers were 198 for Hg, 52 for Cr, 111 for Cd, and 208 for Pb. The obtained quantitative results are shown in Table 1.

  As is clear from Table 1, it was confirmed that the quantitative value in Example 1 was in good agreement with the guaranteed value.

(Comparative example 1) Quantification using the official method of BSEN-1122 Using the same sample as in Example 1, using the decomposition vessel 11 and watch glass 12 shown in FIG. The solution was decomposed with a solution obtained by adding 5 ml of sulfuric acid and 10 ml of nitric acid to 100 ml of pure water.

  After decomposition, sulfuric acid and organic substances were removed at 450 ° C.

After cooling, 5 ml of nitric acid was added to dissolve the residue, and measurement and analysis were performed with an inductively coupled plasma mass spectrometer (SPQ9000 manufactured by Seiko Denshi Kogyo Co., Ltd.) with a high frequency output set to 1.1 kW. The sample solution was introduced into the inductively coupled plasma mass spectrometer using a coaxial quartz nebulizer. The measurement mass numbers were 198 for Hg, 52 for Cr, 111 for Cd, and 208 for Pb. The obtained quantitative results are shown in Table 2. In Table 2, “nd” indicates that no element was detected.

  As is clear from Table 2, in Comparative Example 1, the amount of volatilized Hg is large, and the quantitative result shows a low value. Moreover, it turns out that Pb also precipitates as lead sulfate etc., and the density | concentration is low.

(Example 2) Confirmation of adsorption prevention effect Next, the adsorption effect of Hg in an aqueous solution was examined. The aqueous solution adjusted so that the density | concentration of Hg might be 10 ppm was prepared, and the time-dependent change was confirmed when Au was added to this aqueous solution so that the density | concentration might be 1 ppm, and when Au was not added. The result is shown in FIG.

  As is clear from FIG. 3, a clear difference was observed in the adsorption rate between the case where Au was added to the aqueous Hg solution and the case where only Au was added without adding Au. It can be seen that the presence of Au having a low ionization tendency tends to suppress the reduction of Hg, and that addition of Au or the like is effective in suppressing the adsorption and volatilization of Hg.

(Example 3) Confirmation of additive concentration of coexisting elements
A European polyethylene reference material (BCR-680) whose measured values are guaranteed was prepared as a sample. Using the decomposition vessel 1 and the lid 2 shown in FIG. 1, 0.2 g of a sample is installed, and Au, Pt, Ag, Pd, Ru, and Os ions as coexisting ions are each 0.005 to the known concentration of Hg. To 100 times equivalent, and decomposed at a temperature of 100 ° C. with a solution of 5 ml of sulfuric acid and 10 ml of nitric acid in 100 ml of pure water.

  After dissolution, sulfuric acid and organic substances were removed at 450 ° C.

After cooling, 5 ml of nitric acid was added to dissolve the residue, and measurement was performed with an inductively coupled plasma mass spectrometer (SPQ9000 manufactured by Seiko Denshi Kogyo Co., Ltd.) at a high frequency output of 1.1 kW. The ratio of guaranteed value to the obtained quantitative result is calculated, and the result of calculating the recovery rate is shown in Table 3.

  As is clear from Table 3, each element other than Au ions can be quantified with high accuracy by preventing Hg from evaporating and adsorbing, as with Au ions, if it is an element that has a lower ionization tendency than Hg. It turns out that it is.

  The concentration is preferably 0.01 to 10 times equivalent, more preferably 0.05 to 5 times equivalent. If it is less than 0.01 times equivalent, the effect is not sufficient because the abundance is small, and if the concentration is higher than 10 times equivalent, the matrix desensitization effect in inductively coupled plasma mass spectrometer (ICP-MS) etc. It can be seen that the apparent recovery rate is reduced.

  As described above, according to this embodiment, it is possible to provide a sample pretreatment method and a mercury content measurement method in a sample that can measure the mercury content in the sample more easily and accurately than in the past. it can. As a result, for example, in the industry of managing electronic component materials, it is possible to ensure environmental safety and improve product reliability within device manufacturing.

  In addition, this invention is not limited to the said embodiment and Example. The above-described embodiments and examples are merely examples, and the ones having substantially the same configuration as the technical idea described in the claims of the present invention and exhibiting the same operational effects are any. Are also included in the technical scope of the present invention.

The figure which shows the process of one Embodiment of this invention. The figure which shows the structure of the container used for the decomposition | disassembly process in one Embodiment of this invention. The figure which shows the measurement result of the adsorption effect of Hg in the aqueous solution in Example 2 of this invention. The figure which shows the structure of the container used for the decomposition | disassembly process in a comparative example.

Explanation of symbols

  101... Decomposition step, 102... Organic substance removal step, 103.

Claims (4)

A sample pretreatment method for measuring the amount of mercury in a sample containing a resin material,
A decomposition step of adding at least one of platinum, gold, silver, ruthenium, rhodium, palladium, osmium, iridium, and decomposing the sample with an acid in a solution;
After the decomposition step, an organic matter removing step for removing organic matter in the sample;
A sample pretreatment method comprising:   The abundance in the solution of at least one of platinum, gold, silver, ruthenium, rhodium, palladium, osmium, iridium is 1/100 times equivalent to 10 times equivalent to the amount of mercury in the solution. The sample pretreatment method according to claim 1, wherein:   The decomposition step is performed in a state where the upper opening of the container containing the solution is covered with a lid body whose lower surface is inclined in one direction and inclined toward the side wall of the container. The sample pretreatment method according to claim 1 or 2. A method for measuring the amount of mercury in a sample for measuring the amount of mercury in a sample containing a resin material,
A decomposition step of adding at least one of platinum, gold, silver, ruthenium, rhodium, palladium, osmium, iridium, and decomposing the sample with an acid in a solution;
After the decomposition step, an organic matter removing step for removing organic matter in the sample;
A method for measuring the amount of mercury in a sample, comprising: a quantitative step of quantifying mercury in the sample after the organic matter removing step.

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