JPS5853857B2 - Quantification of trace amounts of indium using flameless atomic absorption spectrometry - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for quantifying trace amounts of indium by flameless atomic absorption spectrometry.

The resistance heating element normally used as a carbon atomizer is a graphite tube with a length of 30 rIrIn, an outer diameter of 6 mm, and an inner diameter of about 4 mm, with a sample injection hole of about 1.5 m in diameter in the center. The quantitative method of the invention atomizes the sample using Joule heat generated by passing an electric current across a resistive heating element, converts the atomic absorption of the atomized indium into a current value, and records it on the chart of a recorder. Based on the height of the recorded absorption peak (...), this method uses a calibration curve prepared in advance using standard solutions to quantify the analyte element.

In this method, by adding zirconium, molybdenum, yttrium, lanthanum, thorium, or tungsten to the part of the carbon atomizer that comes into contact with the sample or to the sample solution, the indium atomization efficiency can be improved and the measurement sensitivity can be significantly increased. It turns out that it is possible to improve.

It was also found that this method has good effects as an interference suppressor for coexisting elements.

The present invention will be explained in detail below.

This example uses the intra-electrode addition method, which is simple to operate and consumes only a small amount of sensitizer, that is, the sensitizer is added in advance to the part of the carbon atomizer that comes in contact with the sample. We will discuss the experimental results in this case.

First, Table 1 shows the optimum measurement conditions for indium determined from the results of experimental studies on various measurement conditions using a solution with an indium concentration of 50 ppb.

Next, the sensitization rate of each sensitizer was investigated according to the measurement conditions shown in Table 1.

The results are shown in Table 2. This sensitization rate is indium concentration 5
This is a value measured using a 0 ppb solution and adding 150 μ2 of a sensitizer.

Table 2 Sensitizing effect of various elements on income A; peak value due to atomic absorption of indium (rIr
In) B: Peak value (rran) of indium atomic absorption measured after adding 150 μ2 of sensitizer to a carbon atomizer. Next, using a solution with an indium concentration of 50 ppb, calculate the amount of each sensitizer added. The relationship between the amount added and the sensitization rate was investigated by changing the amount in stages.

The results are shown in Figure 1.

In FIG. 1, the vertical axis is the sensitization rate, and the horizontal axis is the amount added.

From this result, in the case of molybdenum Mo, a constant effect was shown at an addition amount of 30 μm or more, and in the case of other sensitizers, a constant effect was shown at an addition amount of 90 μm or more, and 150 μm? It can be seen that stable values can be obtained for all sensitizers by adding a certain amount, which is sufficient.

Next, in Figure 2, 150μ of zirconium Zr was added as a sensitizer.
? Or 150μ of molybdenum Mo? An example of a calibration curve when using an added carbon atomizer and when using an additive-free carbon atomizer is shown.

The vertical axis in this figure 2 is the peak height W) due to atomic absorption of indium, and the horizontal axis is the indium concentration pp
It is b.

As a result, when a sensitizer was used, a good linear relationship was obtained, and sufficient practicality was recognized.

Next, nitrates of various elements were added to a solution with an indium concentration of 150 ppb while changing the concentration stepwise, and the influence of coexisting elements was investigated by measuring the peak value due to atomic absorption of indium.

As a result, Cs exhibited desensitizing interference with Na, and L
i.

M? , ca , Ba > Sr, , AI , Cr t
Au)pt and Hf show sensitizing interference, and also Fe
.

Nl, Co>Mn, etc. exhibit complex interferences such as desensitizing interference at low concentrations (around 1 ppm) and sensitizing interferences as the concentration increases; cannot be applied and directly measured.

Figure 3 shows an example of the influence of these coexisting elements.

However, it has been found that by using a carbon atomizer to which the above-mentioned sensitizer is added, all effects of these coexisting elements can be suppressed.

Figure 4 shows an example of zirconium Zr with a thickness of 150μ.
The results are shown using a carbon atomizer to which 150 μm of molybdenum Mo was added.

In this case, the experiment was conducted using a solution with an indium concentration of 50 ppb because the susceptibility increased about three times.

It was also found that the quantitative method of the present invention shows good results in improving reproducibility.

That is, as a result of measuring the coefficient of variation C-V (n=10) using a solution with an indium concentration of 50 ppb, it was 7.77% when using a carbon atomizer without addition, but when zirconium Zr was added. 1.1 for
7%, and when molybdenum Mo was added, it significantly improved to 1.14%.

As described above, according to the present invention, low concentration indium can be analyzed quickly with high sensitivity and accuracy without separating it from coexisting elements in a sample.

[Brief explanation of the drawing]

Figure 1 shows the sensitization rate, Zr 2Mo tY, La tTh
Figure 2 is a graph showing the relationship between the amount of addition of Zr or Mo, and Figure 2 is a graph showing an example of a calibration curve when using a carbon atomizer with Zr or Mo added and a carbon atomizer without additives. The figure is a graph showing an example of the influence of coexisting elements on indium, and FIG. 4 is a graph showing that this influence can be suppressed by adding Zr or Mo.

Claims (1)

[Claims] 1. A flameless atomic absorption spectrometry method characterized by adding zirconium, molybdenum, yttrium, lanthanum, thorium, or tungsten to the contact part of a carbon atomizer with a sample or to a sample solution, and then quantifying a trace amount of indium. Quantitative method for trace amounts of indium.