JPH11287761A - Method for determining metallic element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To speedily, simply and safely determine many kinds of metallic elements in a sample such as a cosmetic, etc., by sequentially adding a strong acid, a hydrofluoric acid, a boric acid to the sample including an inorganic substance, a metal-containing organic substance while irradiating microwaves to the sample. SOLUTION: A sample such as various cosmetics, agricultural chemicals, etc., includes an inorganic substance and a metal-containing organic substance, and also includes a surfactant, an organic solvent, etc. A strong acid of 2 or lower pKa, preferably nitric acid is added by 2-10 ml to 0.1 g of the sample and microwaves are irradiated in a sealing system. Thereafter, a hydrofluoric acid is added by the same quantity as the nitric acid, and microwaves are irradiated again in the sealing system. Because of this two-stage process, particularly, mica, silica or the like inorganic mineral, silicones are completely dissolved, thus enabling correct analyses. Thereafter, a boric acid is added and microwaves are irradiated in the sealing system. Fluoride ions generated in a pre-stage process are masked by this operation, with high determination accuracy secured. The obtained sample solution is subjected to metallic element analysis, whereby metallic elements in the sample are speedily, simply and safely determined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining a metal element in a sample containing organic and inorganic substances such as cosmetics, cosmetics, household cleaners and the like.

[0002]

2. Description of the Related Art In cosmetics, cosmetics, and household cleaning agents,
Various metal element-based inorganic minerals, metal-containing organic substances, and the like are included, and their quantification is performed in terms of quality control. From the viewpoint of safety, it is necessary to determine trace metals such as heavy metals and arsenic in these products.

[0003] Methods of quantifying the metal-containing components in these samples include a method of directly analyzing the elements in the sample by a fluorescent X-ray method without pretreatment, and a method of analyzing the sample after forming it into glass beads. . However, in these methods, in the case of a sample of a cosmetic or a cosmetic, a complex matrix is often included in the sample, and accurate analysis cannot be performed, for example, because there are many types of elements to be analyzed.

On the other hand, there are high-frequency induction, coupled plasma emission spectroscopy (ICP-AES) and atomic absorption spectroscopy (AAS) as polymetal element determination methods, but the sample must be a solution.

[0005] Furthermore, there is a method in which a sample of cosmetics or the like is pre-treated and made into a solution, and then analyzed by ICP-AES or AAS. However, complicated processing and a long time are required for each element to be analyzed.
Automation was difficult.

There is a method in which nitric acid or the like is added to a sample, microwaves are irradiated in an open system, and a sample solution is prepared by thermal decomposition (Japanese Patent Application Laid-Open Nos. 8-68735 and 9-89868). However, in the case of the open system, there is a risk of light element volatilization and contamination. In the closed system, mica and talc could not be decomposed, and sufficient analysis could not be performed.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to rapidly, simply and safely decompose a sample containing a variety of complex matrices, such as cosmetics, containing a plurality of elements in a small amount to a high concentration. Another object of the present invention is to provide a method for analyzing a metal element in the sample with high accuracy.

[0008]

SUMMARY OF THE INVENTION The present inventors have first prepared p-type samples containing a wide variety of inorganic and / or metal-containing organic substances.
A strong acid of Ka2 or less is added, microwave irradiation is performed in a closed system, then hydrofluoric acid is added, microwave irradiation is performed in a closed system, and further, boric acid is added, and a sample irradiated with microwaves in a closed system is analyzed. For example, they have found that various organic and inorganic substances can be efficiently and safely decomposed, and that many metal elements including Al and Si can be analyzed simultaneously and accurately, and the present invention has been completed.

According to the present invention, a sample containing an inorganic substance and / or a metal-containing organic substance is irradiated with a microwave in a closed system after adding a strong acid having a pKa of 2 or less, and then hydrofluoric acid is added to the sample to produce a microwave in a closed system. And then irradiating the sample with microwaves in a closed system after adding boric acid, and then quantifying the metal elements in the sample.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The determination method of the present invention is a method for determining a metal element and a trace metal in an inorganic substance or a metal-containing organic substance. The sample contains an inorganic substance and / or an organic substance containing a metal,
In addition, in addition to these substances, surfactants, natural and synthetic polymer compounds, various oils, organic solvents and the like are included. For example, there are various cosmetics, cosmetics, detergents, quasi-drugs, pharmaceuticals, agricultural chemicals, and the like. Examples of the inorganic substance include inorganic minerals such as mica and talc, and various inorganic salts. Examples of the metal-containing organic substance include silicones and various organic acid salts. The sample is preferably quantified by removing components soluble in hexane, alcohol, chloroform, ether and the like in advance.

In the present invention, first, a strong acid having a pKa of 2 or less is added to the sample, and microwave irradiation is performed in a closed system. Here, as the strong acid having a pKa of 2 or less, one or more selected from hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid and the like can be mentioned, but nitric acid is particularly preferable, concentrated nitric acid is particularly preferable, and aqua regia and the like may be used. In the case of nitric acid, the amount of the acid to be added is 0.1 to 20 ml, preferably 2 to 10 ml, based on 0.1 g of the sample as 70% nitric acid.

The sample to which these acids have been added is irradiated with microwaves in a closed system. The closed container for the closed system is preferably a container having acid resistance, heat resistance and pressure resistance and further having a pressure release function.

The microwave irradiation may be performed by a usual microwave irradiation apparatus, for example, a microwave irradiation apparatus of 2450 ± 50 MHz. The output is not particularly limited, and is usually 250 W
~ 1 kW is preferred. In order to prevent bumping, high pressure and high heat during operation, a device capable of controlling pressure and temperature is desirable.

As for the pressure and temperature during microwave irradiation, the pressure is increased to 75 kg / cm ² or less, preferably several times in a closed state, and is maintained for a certain time (5 minutes or more) in each step;
Alternatively, in a closed state, the temperature is 500 ° C. or less, more preferably 2 ° C.
It is preferable to raise the temperature several times at a temperature of 00 ° C. or less, and to hold the temperature for a certain period of time (5 minutes or more) at each stage.

Next, hydrofluoric acid is added to the sample, and the sample is again irradiated with microwaves in a closed system. Here, the addition amount of hydrofluoric acid is preferably 0.1 to 20 ml, particularly preferably 2 to 10 ml per 0.1 g of the sample as 48% hydrofluoric acid. The microwave irradiation after the addition of hydrofluoric acid is in accordance with the above conditions.

By the two-stage addition of acid and microwave irradiation, components which have been insufficiently decomposed in the past, particularly inorganic minerals such as mica and silica, and silicones can be completely decomposed, and accurate analysis can be performed.

Next, boric acid is added to the sample, and microwave irradiation is performed in a closed system. By this operation, the fluoride ions generated in the pre-stage treatment can be masked, and high quantitative accuracy can be secured. The amount of boric acid added is not particularly limited as long as it can mask the fluoride ions in the sample. Microwave irradiation after the addition of boric acid is also performed using the same apparatus as above, preferably for 1 minute or more, more preferably 1 minute or more.
It may be performed for 10 to 10 minutes.

It is preferable that the samples after the above-described three-stage microwave irradiation are allowed to cool and then to be subjected to the following operation.

When the sample solution thus obtained is subjected to metal element analysis according to a conventional method, the metal element in the sample can be quantified. ICP-AES and AAS are preferred for analysis. For analysis, it is preferable to use an element not contained in the sample (for example, yttrium) as an internal standard component.

According to the method of the present invention, a large number of metal elements can be simultaneously determined only by the sample solution after the three-stage microwave irradiation, for example, Al, Si, Ca, Ti, B
a, Fe, Mg, Zn, As, S, P, K, Na, etc. can be analyzed simultaneously.

[0021]

Next, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto.

Example 1 (1) 0.05 g of a sample obtained by removing alcohol-soluble components from a commercially available foundation was precisely weighed in a decomposition container made of Teflon, 5 ml of concentrated nitric acid was added, and sealed in a pressure container made of polypropylene. The pressure vessel was completely sealed, and decomposed by a microwave decomposition apparatus (MDS2000 manufactured by CHEM) under the microwave output conditions shown in Table 1 below (about 25 minutes). After completion of nitric acid decomposition, it was taken out of the oven and cooled sufficiently.

[0023]

[Table 1]

(2) Next, hydrofluoric acid was added to the sample for 1.5 hours.
After the addition of ml, the safety valve (rupture membrane) was replaced with the same decomposition device as in the above (1), the container was sealed, and the container was decomposed under the microwave output conditions shown in Table 2 (about 25 minutes). After the completion of hydrofluoric acid decomposition, the system was sufficiently cooled at room temperature.

[0025]

[Table 2]

(3) Next, 20 ml of 4% boric acid was added to the sample, and the sample was heated under the microwave output conditions shown in Table 3 by the same decomposition apparatus as in (1) (about 15 minutes). After the completion, it was taken out of the oven and cooled sufficiently.

[0027]

[Table 3]

(4) The decomposition solution is made of polypropylene 100
Transferred to a ml volumetric flask. The decomposition vessel was washed several times with ultrapure water, and the washing solution was also transferred to a 100 ml volumetric flask. Then, 5 ml of an yttrium solution (5000 mg / l) was added, and ultrapure water was added to 100 ml to prepare an analysis sample. This is ICP-
The analysis was performed using AES under the conditions shown in Table 4.

[0029]

[Table 4]

Table 5 shows the results. In comparison with the conventional method, the sample was divided into three parts, and for each, an alkali melting method (for quantitative determination of Ti, Si, Al and Ca), a potassium hydrogen sulfate melting method (for quantitative determination of Fe and Mg) and an acid decomposition method (Zn (For quantification) were separately performed, and I
The results of quantification by CP-AES are also shown. As a result, according to the method of the present invention, simultaneous quantification of Si, Ti, Al, Ca, Fe, Mg and Zn could be performed more accurately than the conventional method.

[0031]

[Table 5]

Example 2 Metal elements were quantified in the same manner as in Example 1 except that a commercially available emulsion sample from which alcohol-soluble components had been removed was used.
As a result, Si, Ti, Al, Fe, Mg, Ca and Zn in the emulsion could be simultaneously determined (see Table 6).

[0033]

[Table 6]

Example 3 A metal element was quantified in the same manner as in Example 1 except that a sample obtained by removing alcohol-soluble components from a commercially available lipstick sample was used. Si, Ti, Al, Fe, Mg, Ca and Zn in the lipstick could be simultaneously determined (see Table 7).

[0035]

[Table 7]

[0036]

According to the method of the present invention, various kinds of metal elements in a sample of cosmetics or the like containing a large number of organic substances and inorganic substances can be quickly and rapidly removed.
Easy and safe quantification. Conventionally, pre-processing, which was performed under different conditions for each element or sample, can now be performed in a single operation, so that simultaneous analysis of various elements has become possible and accuracy has been improved. If a disassembly program is used, automatic disassembly can be performed.

Claims (1)

[Claims] 1. A sample containing an inorganic substance and / or a metal-containing organic substance is added with a strong acid having a pKa of 2 or less and irradiated with microwaves in a closed system. A method for quantifying a metal element in a sample, which comprises irradiating the sample, then adding boric acid, irradiating the sample with microwaves in a closed system, and then quantifying the metal element in the sample.