JPH0552773A - Method for pretreament of sample for analysis - Google Patents

Abstract

PURPOSE:To obtain a method for pretreatment of a sample of analysis with high detecting sensitivity which can be simply executed, and enables a microanalysis of an element and analysis of Cl. CONSTITUTION:A fixed amount of a liquid sample as a sample for analysis is dropped onto a metallic plate or a metallic foil and dried to make the dropped liquid adhere onto the metallic plate or metallic foil, A corrosive component reacting with the metallic plate or metallic foil is added to the liquid sample. The reason for this is to prevent the loss of the component of the liquid sample thereby to enhance the analyzing accuracy by securely fixing the dropped liquid to the metallic plate or metallic foil in the drying process. The X-ray fluorescence analysis is used for the analyzing means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for pretreating an analytical sample, and is applied to the analysis of elements contained in liquid samples such as factory water, waste water and various beverages.

[0002]

2. Description of the Related Art Generally, fluorescent X-ray analysis is capable of pretreatment of a sample, easy operation, short measurement time, high detection sensitivity, and spectrally separated and quantified elements to be measured. Therefore, it is widely used for research and analysis for quality control in the technical fields of steel, glass, cement, foods, beverages and the like.

[0003] The pretreatment (preparation) of the sample for the fluorescent X-ray analysis has a great influence on the operation time at the time of analysis, the accuracy of analysis, etc., and is one of the important factors before the analysis. Is. Conventionally, as a sample pretreatment,
The following methods are known, which will be described in order according to the form of the sample.

When the sample is in the form of a solid, the sample is simply smoothed, ground and measured, or crushed into tablets. In the case of powders, tablets, briquettes or glass beads are generally used. Further, in the case of a liquid, there is a pretreatment method such as transferring the sample as it is to a measurement container, or instilling the sample on a filter paper or a membrane filter and drying.

[0005]

However, according to such a conventional sample pretreatment method, when the sample is a liquid, in the method of transferring the liquid sample to the measuring container and measuring, the component to be analyzed is diluted with the solvent. Since the fluorescent X-ray analysis is performed as it is, the detection sensitivity is low. Further, since a film such as polypropylene or Mylar is used for the measuring surface in the measuring container, fluorescent X-rays are absorbed therein, so that the detection sensitivity of the measuring elements of light elements is considerably lowered.
In addition, since the fluorescent X-ray intensity is generally measured in a vacuum, there is a problem that special care is required in handling and the operation is likely to cause anxiety.

According to a conventional pretreatment method in which a liquid sample is dropped on a filter paper or a membrane filter and dried, pp
The detection sensitivity is low when applied to microanalysis of m or less. Further, since both the filter paper and the membrane filter contain Cl as an impurity, there is a problem that they cannot be applied to trace analysis of Cl. The problem to be solved by the present invention is to provide a pretreatment method for an analytical sample with high detection sensitivity, which maintains the simplicity of the operation, enables sub-ppm level trace amount analysis, and can analyze Cl. is there.

[0007]

A method for pretreating an analytical sample according to the present invention for solving the above-mentioned problems is a method for pretreating a sample used in X-ray fluorescence analysis, in which a fixed amount of a liquid sample is treated with a metal. The method is characterized in that a drop is dropped on a plate or a metal foil, and the dropped drop is dried. In the pretreatment method for the analysis sample, the liquid sample to be analyzed may contain a corrosive component that reacts with the metal plate or the metal foil. This is because the dropped droplets are fixed to the metal plate or the metal foil during the drying process to eliminate the loss of the droplet components and improve the analysis accuracy. A fluorescent X-ray analysis method is used as the analysis means.

[0008]

EXAMPLES Examples of the present invention will be described below. The procedure of the pretreatment method for a liquid sample is as follows. A metal foil, for example, an Al foil for cooking is prepared. In the case of metal foil, smooth the metal foil.

Quantitation of liquid samples, preferably 10-20
An aliquot of 0 μl is instilled on the metal foil with a micropipette, for example an Eppendorf pipette 4710. Air-dry the liquid sample on the metal foil. Instead of natural drying, it is preferably 50 in a vacuum dryer or an electric constant temperature dryer.
You may dry at low temperature around ℃. Cut off the metal foil of the part where the liquid sample is drip,
The cut metal foil is attached to a folder for measuring fluorescent X-ray intensity.

Here, the metal foil is cut off after the liquid sample is dropped onto the metal foil, but the liquid sample may be dropped onto the cut metal foil in advance. It is also possible to use a clean metal plate, for example, a silicon wafer, instead of the metal foil. Furthermore, if the liquid sample to be analyzed contains a corrosive component that reacts with the metal foil, such as a small amount of hydrochloric acid, nitric acid, sodium hydroxide, potassium hydroxide, the drip-dried droplets will satisfactorily form on the metal foil during the drying process. It sticks and enables more accurate measurement.

Comparative Test 1 Next, the detection sensitivities of the pretreatment method of the example of the present invention and the conventional filter paper drip method were compared by fluorescent X-ray analysis. Al was used for the metal foil of the pretreatment method of the example of the present invention. Graphs comparing the calibration curves of each element of Cl, P, S, Ti, K, Ca, and Na by the fluorescent X-ray analysis are shown in FIGS.

1 to 7 show an Al foil drip method according to an embodiment of the present invention (shown by a solid line in FIGS. 1 to 7) and a conventional filter paper drip method (shown by a dotted line in FIGS. 1 to 7). Shows how the fluorescent X-ray intensity changes depending on the concentration of the measured element. From this, Table 1 shows the results in which the detection sensitivities of the respective analysis elements are summarized.

[0013]

[Table 1]

As shown in Table 1, for example, the analytical element C
For l, sensitivity of fluorescent X-ray intensity by Al foil drip:
225cps / μgCl, fluorescent X by conventional filter paper drip
Line intensity sensitivity: 40 cps / μg Cl. For other elements, P, S, Ti, K, Ca, Na, the sensitivity of the fluorescent X-ray intensity by the Al foil drip and the sensitivity of the fluorescent X-ray intensity by the conventional filter paper drip are shown in Table 1. Is.

From the results shown in Table 1, it can be seen that the pretreatment method according to the example of the present invention has an average detection sensitivity (analysis sensitivity) of about 3.5 times that of the conventional filter paper drip method. Further, it can be easily inferred that the pretreatment by the method of the present invention enhances the analysis sensitivity for the analysis of other elements not shown in the experiment. Comparative test 2 Various metals such as Al, Ti, and N are used as materials for holding the droplets of the sample.
i, Si metal foil or metal plate was used. The calibration curves in this case were compared using Cl as an analytical element as an example.

A 100 μl liquid sample was instilled. The result is as shown in FIG. The type of metal foil is A
I foil, Ti foil, Ni foil, and Si plate were used. As is clear from FIG. 8, it is understood that the detection sensitivity is almost the same regardless of the type of metal foil or metal plate. The drip-driving liquid contained corrosive components that reacted with the metal foil and did not affect the analysis, such as acids and alkalis. This is because when the corrosive component is contained in the liquid to be drip, since the drip-formed product on the metal foil firmly adheres to the metal foil, there is no component loss of the liquid sample, so that the analysis accuracy is further improved. This is because that. As the acid or alkali in the liquid to be drip, for example, HCl is preferable for Al foil, NaOH, HCl is for Ti foil, and HCl is HNO _{3 for} Ni foil.

Comparative Test 3 The materials holding the droplets of the samples were compared with respect to the drip performance, the reproducibility of the drip fluorescent X-ray intensity measurement, and the Cl analysis.
The results are shown in Table 2. In Table 2, "○": good,
“X”: indicates not possible.

[0018]

[Table 2]

In Example 1 of the present invention, the metal Al foil was used as the material for holding the droplets of the sample. However, as an alternative material, a conventional filter paper (Comparative Example 1) and a polypropylene film (Comparative Example) were used. 2) and a polycarbonate film (Comparative Example 3) were used. As shown in Table 2, Comparative Example 1 cannot be used for the analysis of Cl as the measurement element, because the filter paper itself which is the sample holding material itself contains Cl because of the manufacturing method. Further, the filter paper has lower sensitivity than the case where the metal Al foil is used. The polypropylene film of Comparative Example 2 and the polycarbonate film of Comparative Example 3 could not be used for fluorescent X-ray analysis because the droplets did not adhere well when the sample was dried.

Comparative Test 4 Next, Cl in the silicon nitride raw material powder was analyzed. Cl in the silicon nitride raw material powder was collected as a liquid together with water vapor by the pyrohydrolysis method, and analyzed by the pretreatment method of the present invention. Samples A to H shown in Table 3 were compared with the conventional filter paper drip method. The results are shown in Table 3.

[0021]

[Table 3]

As can be seen from Table 3, according to the method of the present invention, the amount of Cl can be measured up to the order of a trace value of 100 ppm or less. With the conventional filter paper drip method, it was impossible to analyze a sample with a minute amount of Cl content of 100 ppm or less. Further, according to the pretreatment method according to the embodiment of the present invention,
It turned out that pm level analysis is possible. As a comparative test 5 analysis method, a fluorescent X-ray analysis method was used. This is another analysis method, such as ion chromatography method, ion meter method,
Although there are mercury thiocyanate absorptiometry and the like, in ion chromatography, interference peaks are likely to appear and accurate measurement may not be possible. Trace C
This is because it is not suitable for l analysis.

Comparative Test 6 The Cl analysis value of the silicon nitride raw material powder to which the present invention was applied was applied to the fluorescent X-ray analysis by the powder molding method to prepare a calibration curve. When the data values of the pretreatment method according to the example of the present invention are plotted, a very good straight line is shown, as indicated by the mark "O" in FIG. This shows that the pretreatment method according to the embodiment of the present invention enables accurate analysis. Therefore, for example, the amount of Cl in the raw material powder is first accurately determined by the above pretreatment method, a calibration curve as shown in FIG. 9 is obtained, and the subsequent analysis of Cl in the raw material powder is a simpler operation method. X-ray fluorescence analysis by powder molding can be used.

On the other hand, when the analysis value by the conventional filter paper drip method is used for the horizontal axis, as shown by the "x" mark in FIG.
Since the quantitative value of the filter paper drip method is inaccurate, the calibration curve does not become a straight line and cannot be put to practical use.

[0025]

As described above, according to the method for pretreating an analytical sample of the present invention, the operation of the drip method is kept simple, the detection sensitivity is remarkably improved, and the sub-ppm level trace elemental analysis can be performed. It is possible to analyze Cl, which is possible.

[Brief description of drawings]

FIG. 1 is a characteristic diagram in which the detection sensitivity by the pretreatment method of the present invention and the detection sensitivity by the conventional filter paper drip method are compared with respect to the measurement element Cl.

FIG. 2 is a characteristic diagram in which the detection sensitivity by the pretreatment method of the present invention and the detection sensitivity by the conventional filter paper drip method are compared for the measurement element P.

FIG. 3 is a characteristic diagram in which the detection sensitivity by the pretreatment method of the present invention and the detection sensitivity by the conventional filter paper drip method are compared for the measurement element S.

FIG. 4 is a characteristic diagram in which the detection sensitivity by the pretreatment method of the present invention and the detection sensitivity by the conventional filter paper drip method are compared for the measurement element Ti.

FIG. 5 is a characteristic diagram in which the detection sensitivity by the pretreatment method of the present invention and the detection sensitivity by the conventional filter paper drip method are compared for the measurement element K.

FIG. 6 is a characteristic diagram in which the detection sensitivity by the pretreatment method of the present invention and the detection sensitivity by the conventional filter paper drip method are compared for the measurement element Ca.

FIG. 7 is a characteristic diagram in which the detection sensitivity by the pretreatment method of the present invention and the detection sensitivity by the conventional filter paper drip method are compared for the measurement element Na.

FIG. 8 is a characteristic diagram comparing fluorescent X-ray intensity characteristics that vary depending on the concentration of a measurement element Cl for various metal foils or metal plates.

FIG. 9 is a characteristic diagram comparing the detection sensitivity of the pretreatment method of the present invention with the detection sensitivity of the conventional filter paper drip method.

Claims (2)

[Claims] 1. A method for pretreating a sample used in a fluorescent X-ray analysis method, which comprises dropping a fixed amount of a liquid sample on a metal plate or a metal foil, and drying the dropped droplets. Sample pretreatment method. 2. A liquid sample containing a corrosive component that reacts with a metal plate or a metal foil, and the drip-dried droplets are fixed to the metal plate or the metal foil in a drying process. Pretreatment method for the analytical sample described.