JP2012215406A - Sample preparation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sample preparation method with which, when preparing a sample to which an organic film such as a liquid crystal glass panel is deposited into a fluorescent X-ray analysis briquette or the like, the analysis briquette or the like can be prepared easily by grinding the sample without removing an organic substance through calcination.SOLUTION: A sample preparation method is characterized in that a sample containing an organic substance is frozen and ground at -50°C or lower, preferably, at -79°C or lower and a particle size D95 (cumulative 95 vol.% diameter) of the ground result is made into 500 μm or less, preferably, 400 μm or less. The sample preparation method is applied to, for example, a sample containing an organic substance of which weight decrease at 200 to 500°C is 5% or more.

Description

The present invention relates to a sample preparation method capable of easily immobilizing a sample containing an organic substance in a container of an analyzer. The sample preparation method of the present invention is useful, for example, when a sample to which an organic film such as a liquid crystal panel is attached is prepared on a briquette for fluorescent X-ray analysis.

A fluorescent X-ray analysis briquette is generally prepared by packing a powder sample in an analysis container such as an aluminum or vinyl chloride ring or cup and immobilizing it by applying a pressure of 5 to 50 t. However, when it is difficult to fix the sample due to the particle size of the powder or the mixed substances, for example, it is known to mix a polymer compound such as polyester into the sample as a binder to fix the sample in the analysis container. (Non-Patent Document 1). In addition, for samples of organic matter such as plastic, a sample may be pulverized using a freeze pulverizer to produce a briquette for fluorescent X-ray analysis (Non-patent Document 2).

In recent years, as represented by a liquid crystal panel, a large amount of a material having an organic film attached to glass has been used. However, a material in which an organic film or the like is attached to glass is pulverized even if it is put in an ordinary pulverizer, but the film is soft and is not pulverized finely even if it is partially broken. For example, when a liquid crystal glass panel is pulverized with a vibration mill, the glass portion is pulverized but the organic matter is not crushed. Even if the pulverized material in such a state is packed in an analysis container, a good briquette suitable for analysis cannot be prepared.

When a polymer compound is used as a binder, the analysis accuracy may be reduced depending on the type and amount of the polymer compound. In addition, organic substances contained in the sample can be burned and removed, but in this case, there is a concern that low boiling point metals such as arsenic, selenium, and lead contained in the sample volatilize.

X-ray fluorescence analysis guide (third edition), published by Rigaku Denki Kogyo Co., Ltd. Actual X-ray fluorescence analysis 12th X-ray analysis workshop text (published by the Analytical Society of Japan, X-ray analysis study round-table conference)

The present invention solves the above-mentioned conventional problems with respect to a method for preparing a sample of a material to which an organic substance is adhered. Specifically, the present invention provides a sample preparation method that can easily prepare a briquette for analysis when a sample to which an organic film such as a liquid crystal glass panel is attached is prepared as a briquette for fluorescent X-ray analysis. I will provide a.

The present invention relates to a sample preparation method having the following configuration.
[1] A sample preparation method, wherein a sample containing an organic substance is freeze-pulverized at −50 ° C. or less, and the particle size D95 (cumulative 95 volume% diameter) of the pulverized product is reduced to 500 μm or less.
[2] The sample preparation method according to [1], which is applied to an organic substance-containing sample whose weight loss at 200 to 500 ° C. is 5% or more.

The sample preparation method of the present invention can prepare a good briquette or the like suitable for analysis by fixing it to an analysis container even with a sample to which an organic substance is attached. In addition, since the sample preparation method of the present invention is not a method for removing organic substances contained in a sample by burning, low-boiling point metals such as arsenic, selenium, and lead do not volatilize, and highly accurate analysis is possible. .

The sample preparation method of the present invention can be applied to sample preparation for solid direct analysis such as fluorescent X-ray analysis, solid state emission analysis, glow discharge emission analysis, glow discharge mass spectrometry, etc. A good analytical sample can be easily prepared. These analysis methods have the advantage that the analysis time is significantly shorter than that of the wet analysis method, and this advantage can be maintained according to the sample preparation method of the present invention.

Hereinafter, the present invention will be specifically described based on embodiments.
The present invention is a sample preparation method characterized in that a sample containing an organic substance is freeze-pulverized at −50 ° C. or less, and the particle size D95 (cumulative 95 volume% diameter) of the pulverized product is 500 μm or less.

In the sample preparation method of the present invention, the sample containing an organic substance is, for example, a liquid crystal glass panel or a laminated glass sandwiching an organic film. In the liquid crystal glass panel, a polarizing filter, a liquid crystal molecular layer, an ITO transparent layer, and the like formed of an organic material are laminated on the back side of the display. When the discarded liquid crystal glass panel is melt-treated at a smelter or the like, these are crushed and subjected to fluorescent X-ray analysis or the like in order to determine the type of the glass part or metal part. The sample preparation method of the present invention can be applied to these liquid crystal glass panels as a sample containing an organic substance.

For example, a sample to which the sample preparation method of the present invention is applied is effective when the weight loss at 200 to 500 ° C. is an organic content of 5% or more. In general, when a sample containing an organic substance having a weight loss of 5% or more is subjected to fluorescent X-ray analysis, the analysis accuracy decreases.

In the sample preparation method of the present invention, a sample containing an organic substance is freeze-ground at −50 ° C. or lower. The temperature for freeze pulverization is suitably −50 ° C. or lower, and preferably −70 ° C. or lower. A freezing refrigerant may be introduced into the pulverization chamber and pulverized. When the pulverization temperature is higher than −50 ° C., there is a concern that the organic matter is not sufficiently pulverized. If liquid nitrogen is used as the refrigerant, it can be freeze-ground at about -196 ° C, and if dry ice is used, it can be freeze-ground at about -79 ° C. When freeze-pulverized at about -196 ° C using liquid nitrogen, both organic and inorganic substances are frozen and can be easily pulverized to a target particle size range (D95: 500 µm or less).

In the sample preparation method of the present invention, freeze pulverization is performed so that the particle size D95 (cumulative 95% by volume) of the pulverized product is 500 μm or less, preferably 400 μm or less, more preferably 350 μm or less. If the particle size D95 of the pulverized product is larger than 500 μm, for example, when a briquette for fluorescent X-ray analysis is prepared, coarse particles of organic matter are included, and there is a concern that the analysis accuracy may be lowered. In addition, when the particle size of the pulverized product is large, a part of the powder may spill from the surface of the container without being sufficiently fixed when packed in the analysis container, or the surface may be cracked.

Examples of the present invention and comparative examples are shown below. A commercially available machine (model name: SPEX 6770 type) was used as the freeze pulverizer. An aluminum ring or a PVC ring having a diameter of 20 mmφ was used as a press sample for fluorescent X-ray analysis.

[Example 1]
About 4 g of coarsely crushed flat panel display glass crushed material was collected and placed in a frozen powder container. Liquid nitrogen was used as a refrigerant for freeze grinding, and freeze grinding was performed at -196 ° C. The crushing time was 3 minutes twice to prevent the apparatus from generating heat. When the particle size distribution of the powder obtained by freeze pulverization was measured by a laser scattering method, D95 was about 350 μm. Furthermore, when the weight loss of this powder was measured by TG-DTA, it was about 20%. This powder was packed so that the sample was filled in the ring before pressing, and a press sample for fluorescent X-ray analysis was prepared. It was.

[Example 2]
Except for adjusting the pulverization time, freeze pulverization was carried out in the same manner as in Example 1 to obtain pulverization having the particle size distribution shown in Table 1. These powders were put into an analysis container (the above aluminum ring) and press-molded. As shown in Table 1, sample No. 1 with D95 of 650 μm has cracks on the briquette surface. On the other hand, sample No. 1 with D95 of 500 μm and sample No. 3 with 350 μm both have a smooth briquette surface, and a good analytical sample can be obtained.

Example 3
Free pulverization was carried out in the same manner as in Example 1 except that a coarse crushed glass of a flat panel display different from Example 1 was used, dry ice was used as a refrigerant for freeze pulverization, and it was frozen at -79 ° C. When the particle size distribution of the powder obtained by freeze pulverization was measured by a laser scattering method, D95 was about 400 μm. Furthermore, when the weight loss of this powder was measured by TG-DTA, it was about 25%. When this powder was packed in the ring before press so that the sample was filled and a press sample for fluorescent X-ray analysis was prepared, press molding was easy with either an aluminum ring with a diameter of 20 mmφ or a PVC ring. It was.

[Comparative Example 1]
When the coarse pulverized glass of the flat panel display similar to that in Example 1 was pulverized with a vibration mill, the organic matter film could not be pulverized and an analytical briquette could not be prepared.

[Comparative Example 2]
When ethylene glycol (liquid temperature −20 ° C.) was introduced into the pulverization chamber and pulverized, the organic matter fill could not be sufficiently pulverized.

Claims (2)

A sample preparation method characterized by freeze-pulverizing a sample containing an organic substance at −50 ° C. or less and setting the particle size D95 (cumulative 95 volume% diameter) of the pulverized product to 500 μm or less.
The sample preparation method according to claim 1, which is applied to an organic matter-containing sample having a weight loss of 200 to 500 ° C. of 5% or more.