JP2539557B2 - Analytical sample pretreatment method - Google Patents

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 In general, 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 this 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 analysis. Is. Conventionally, as the pretreatment of the sample,
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 to a measurement container as it is, or dropping the sample onto 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. In addition, since a film such as polypropylene or Mylar is used for the measurement surface in the measurement container, fluorescent X-rays are absorbed therein, so that the detection sensitivity of light elements for measurement is considerably lowered.
In addition, since the measurement of the fluorescent X-ray intensity is generally performed in a vacuum, there is a problem that special care is required in handling and anxiety is likely to remain in the operation.

According to the 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 operation, enables sub-ppm level trace amount analysis, and enables Cl analysis. 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 a fluorescent X-ray analysis method, in which a fixed amount of a liquid sample is treated with aluminum. Drip on a plate or aluminum foil,
It is characterized in that the dropped droplets are dried. The pretreatment method of analyzing a sample may contain an alkali that reacts with the aluminum <br/> plate or aluminum foil in a liquid sample to be analyzed. This is a drip droplets in the drying process
This is because by fixing to a minium plate or aluminum foil, loss of droplet components is eliminated and analysis accuracy is improved.
A fluorescent X-ray analysis method is used as the analysis means.

[0008]

Embodiments of the present invention will be described below. The procedure of the liquid sample pretreatment method is as follows. An aluminum foil, for example, an Al foil for cooking is prepared. In the case of Al foil, smooth the Al foil.

Quantitation of liquid samples, preferably 10-20
A fixed amount of 0 μl is instilled on the Al foil with a micropipette, for example an Eppendorf pipette 4710. Allow the liquid sample on the Al foil to air dry. 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 Al foil in the part where the liquid sample is drip,
The cut Al foil is attached to a fluorescent X-ray intensity measurement folder.

[0010] Here, after infusion of a liquid sample to Al foil, although cut Al foil, may be a liquid sample was instilled into Al foil cut in advance. Furthermore, if the liquid sample to be analyzed contains an alkali that reacts with the Al foil, for example, a small amount of sodium hydroxide, potassium hydroxide, etc., the drip drops will adhere well to the Al foil during the drying process, resulting in higher accuracy. High measurement is possible.

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:
225 cps / μg Cl, fluorescence X from 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 compared as shown in Table 1. Is.

From the results 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. Moreover, it can be easily analogized 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 substantially the same regardless of the type of metal foil or metal plate. The drip liquid contained an alkali that reacted with the metal foil and did not affect the analysis. This is because when the liquid to be drip contains an alkali , the drip-formed product on the metal foil firmly adheres to the metal foil, so there is no component loss of the liquid sample, and therefore the analysis accuracy is further improved. is there. As the alkali in the liquid to be drip, for example, NaOH and KOH are desirable.

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

[0018]

[Table 2]

In Example 1 of the present invention, a metal Al foil was used as a 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 contains Cl for the reason 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 having 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, the sub-p
It turned out that pm level analysis is possible. Comparative Test 5 As the 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, ion chromatographic methods often give rise to interfering peaks, which may result in inaccurate measurement. 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 on 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 analysis sample of the present invention, the operation of the drip method is kept simple, the detection sensitivity is remarkably improved, and the trace amount elemental analysis of sub-ppm level 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 comparing the detection sensitivity by the pretreatment method of the present invention and the detection sensitivity by the conventional filter paper drip method 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 the fluorescent X-ray intensity characteristics that vary depending on the concentration of the 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)

(57) [Claims] 1. A fixed amount of a liquid sample is placed on a metal plate or metal foil.
For fluorescent X-ray analysis
In the pretreatment method for analytical samples in 1., the metal plate or metal foil to which the drip drops are adhered is
The liquid to be drip contains alkali and is
A pretreatment method for an analytical sample, wherein the body sample corrodes the aluminum . 2. An element to be analyzed by X-ray fluorescence analysis is chlorine.
Pretreatment method for analyzing a sample according to claim 1, wherein the that.