JP2007327797A - High-frequency inductively coupled plasma emission spectrometric analysis method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-frequency inductively coupled plasma emission spectrometric analysis method of high analytical accuracy and high reliability for arsenic-containing solutions. <P>SOLUTION: The high-frequency inductively coupled plasma emission spectrometric analysis method for arsenic-containing solution is a composition-analyzing method, where the concentration of arsenic in the arsenic-containing solution is measured in a photometric time that brings the measurement dispersion of arsenic to 0.025 mg/l or smaller. According to this method, high-accuracy and reliable analysis becomes possible. Furthermore, higher accuracy and reliability analysis becomes possible, by making a liquid with a pH of 6-8 pass through the measuring sample inlet part, through which the measuring sample is passed, of the high-frequency inductively coupled plasma emission spectrometric analyzer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The composition analysis of the intermediate product of the product was performed, the preparation result of the next process was selected by using the analysis result, the composition of the final product was adjusted, and the product abnormality was detected. The analysis of the intermediate product requires an analysis with a short analysis period without reducing the analysis accuracy as the production line speeds up.

Patent Document 1 discloses a method of stabilizing measurement values by grasping changes in sample conditions and analysis conditions in advance and setting analysis conditions for high performance liquid chromatography based on the information.

JP-A-6-18504

However, in order to determine the analysis conditions by the high-speed chromatography method of Cited Document 1, it is necessary to grasp the composition of the sample, and it takes time for the analysis time to calculate the analysis conditions for each sample. It was difficult to measure with high accuracy and reproducibility.

As a result of intensive studies, the present inventor has obtained the knowledge that high-frequency inductively coupled plasma emission spectroscopy (hereinafter referred to as ICP) can be analyzed with high accuracy and high reliability.

In order to solve the above-mentioned problems, the high frequency inductively coupled plasma optical emission spectrometry method for an arsenic-containing solution according to the present invention provides a arsenic solution containing the arsenic in a photometric time in which the measurement variation of arsenic is 0.025 mg / l or less It is characterized by measuring the concentration.
By the above method, it becomes possible to perform highly accurate and highly reliable analysis.

  Further, in the high frequency inductively coupled plasma emission spectroscopic analysis method for a solution containing arsenic, a liquid having a pH of 6 or more and 8 or less is passed through the measurement sample introduction part through which the measurement sample of the high frequency inductively coupled plasma emission spectrometer is passed. The arsenic concentration of the solution containing arsenic is measured at a photometric time in which the measurement variation of arsenic is 0.025 mg / l or less.

  By the above method, it is possible to efficiently remove the residual sample remaining in the sample introduction part, in particular, it is possible to efficiently remove arsenic (As), and a highly accurate and highly reliable analysis can be performed. Can be possible.

  Provided is a high frequency inductively coupled plasma emission spectroscopic analysis method capable of improving the analysis accuracy of a solution containing arsenic and enabling highly reliable analysis.

  Hereinafter, embodiments of the present invention will be described. Fig. 1 shows a flowchart of the procedure for preparing a sample to be analyzed by ICP. First, 50 ml of the solution in which the analysis sample is dissolved in the beaker and 1-2 ml of nitric acid are added to completely dissolve the analysis sample. Thereafter, the solution is heated, and the solvent is evaporated and concentrated. The concentrated solution was cooled to room temperature, transferred to a 50 ml volumetric flask, added with pure water to make a constant volume of 50 ml, and used as an analytical sample. The measurement sample is preferably a sample having a concentration of 0.1 to 1.0 mg / L because it enables analysis with high accuracy.

The analysis sample is used for analysis by ICP. The analysis sample is passed through the sample introduction part of the high-frequency inductively coupled plasma emission spectroscopic analyzer to emit plasma. The light emitted from the plasma measurement sample is measured for a predetermined time to obtain one photometric value. At this time, the time when the photometry is performed is set as the photometry time. After performing this photometry several times, the average of the photometric values is taken as one measurement value. Here, it is preferable that one photometry time is 4 seconds or more and 7 seconds or less because a sufficient amount of light can be received and disturbance noise can be suppressed. The number of photometry is preferably 3 or more times with the same sample, and the average value is taken as the measurement value, which can further reduce measurement variation. Further, the variation can be reduced as the number of times of photometry is increased. However, when the number of times of photometry is increased, it takes time to calculate a measured value and the like.

In addition, the sample remaining in the measurement sample introduction part can be efficiently removed by passing a solution containing no metal element in the measurement sample introduction part before and after the analysis measurement. This is preferable because it is possible. In particular, the use of pure water is preferable because the amount of As contained in the subsequent measurements can be reduced below the lower limit of quantification.
The washing time is preferably 20 seconds or longer. If the cleaning time is 20 seconds or less, the residual impurities are not sufficiently cleaned, and a signal is generated by the sample remaining in the measurement sample introduction part.

(Reference example)
Using a blank solution in which concentrated nitric acid with a purity of 70% was diluted 50 times, the average of the measured values for 5 seconds of photometry and 3 times of photometry was taken as 1 measurement, and 10 measurements were taken to calculate the standard deviation at that time. The lower limit of quantification was calculated by multiplying the standard deviation by 10. The lower limit of quantification is arsenic (As), cadmium (Cd), copper (Cu), iron (Fe), lead (Pb), selenium (Se), zinc (Zn), and the lower limit of quantification is 0.018 mg / L, They were 0.0004 mg / L, 0.011 mg / L, 0.002 mg / L, 0.01 mg / L, 0.025 mg / L, and 0.005 mg / L.

Example 1
2 ml of nitric acid is added to 50 ml of the analysis solution in which 100 mg of the analysis sample is dissolved to completely dissolve the solute. The solution was heated and concentrated to about 30 ml, cooled by heat dissipation, and then pure water was added to make the total liquid volume 50 ml.
The sample was used for measurement with a high frequency inductively coupled plasma optical emission spectrometer.
As measurement conditions for this sample, the measurement value variation when the photometry time is 5 seconds, the photometry times are 3, 5, and 10 is shown in FIG. The measurement variation was calculated by measuring each number of times, calculating the standard deviation at that time, and multiplying the standard deviation by three. The measurement variations of As, Cd, Cu, Pb, Se, and Zn are 0.006 mg / l, 0.005 mg / l, 0.006 mg / l, 0.009 mg / l, and 0.009 mg / l when the number of photometry is three times, respectively. l, 0.006 mg / l, 0.014 mg / l, 0.009 mg / l, 0.006 mg / l, 0.009 mg / l, 0.022 mg / l, 0.009 mg / l, photometry at 5 times of photometry The number of times was 0.007 mg / l, 0.004 mg / l, 0.005 mg / l, 0.007 mg / l, 0.008 mg / l, and 0.005 mg / l at 10 times.

(Comparative Example 1)
FIG. 2 shows variations in measured values of the same sample as in Example 1 measured with the high frequency inductively coupled plasma emission spectrometer when the photometry time is 3 seconds, the photometry frequency is 3, 5, and 10 times. . The measurement variation was calculated by the same method as in Example 1. The measurement variations of As, Cd, Cu, Pb, Se, and Zn are 0.018 mg / l, 0.014 mg / l, 0.012 mg / l, 0.009 mg / l, and 0.027 mg / l, respectively, at three photometry times. l, 0.012 mg / l, 0.044 mg / l, 0.032 mg / l, 0.027 mg / l, 0.045 mg / l, 0.044 mg / l, 0.033 mg / l, photometry at 5 times of photometry The number of times was 0.027 mg / l, 0.024 mg / l, 0.023 mg / l, 0.026 mg / l, 0.035 mg / l, and 0.024 mg / l at 10 times.

(Comparative Example 2)
FIG. 2 shows the results of measuring the variation in measured values of a sample similar to Example 1 when the photometric time is 10 seconds and the number of photometry is three. The measurement variation was calculated by the same method as in Example 1. The measurement variations of As, Cd, Cu, Pb, Se, and Zn are 0.024 mg / l, 0.018 mg / l, 0.021 mg / l, 0.021 mg / l, and 0.028 mg / l, respectively, at three photometry times. l, 0.022 mg / l.

As shown in FIG. 2, in contrast to the measurement variations in the 3-second photometry in Comparative Example 1 and the 10-second photometry in Comparative Example 2, the 5-second photometry in Example 1 is a highly reliable measurement with a small measurement variation. In particular, 3 times and 10 times metering shows a measurement variation of 0.01 mg or less, indicating that a more reliable analysis is possible.

(Example 2)
After the measurement in Example 1, a blank solution (pH≈0.5) in which concentrated nitric acid with a purity of 70% was diluted 50 times was passed through the measurement sample introduction part of the high-frequency inductively coupled plasma emission spectrometer, and the residue in the apparatus Was washed. While passing through the blank solution, photometry was performed with a photometry time of 5 seconds to confirm residual impurities in the apparatus. The photometric results are shown in FIG. From the figure, it can be seen that the elements of Cd, Cu, Pb, Se, and Zn are below the lower limit of quantification after being washed for 90 seconds with a cleaning solution using nitric acid, and As is washed and removed from the apparatus. Also, the value above the lower limit of quantification is shown, and it can be seen that it has not been completely removed.

(Example 3)
In Example 2, after analyzing a standard solution containing 1 mg / L of As, which contained a large amount of residual impurities in the apparatus, a nitric acid solution (pH≈0) in which concentrated nitric acid having a purity of 70% was diluted about 16 times, 50 times After washing with a diluted nitric acid solution (pH≈0.5) and pure water (pH = 8) for 30 seconds, the measurement was performed at a photometric time of 5 seconds. The measurement results are shown in FIG. From the figure, the nitric acid solution diluted 16 times showed 0.04 mg / L, and the nitric acid solution diluted 50 times showed 0.03 mg / L, which was higher than the lower limit of quantification, but when washed with pure water. In addition, the concentration of As in the cleaning solution can be reduced to a concentration lower than the lower limit of quantification of 0.018 mg / L, enabling highly reliable analysis and reducing the time required for analysis because the time required for cleaning is reduced. I was able to.

It is a measurement sample preparation procedure of ICP in the embodiment of the present invention 6 is a graph showing variations in measurement elements according to photometric conditions in Example 1, Comparative Example 1, and Comparative Example 2. (sec) represents seconds. It is a graph showing the time-dependent change of the residual impurity in blank solution washing | cleaning. (sec) represents seconds. In Example 3, it is a figure which shows the residual impurity density | concentration in the apparatus by the washing | cleaning liquid.

Claims (2)

In the high-frequency inductively coupled plasma emission spectroscopic analysis method for a solution containing arsenic, the arsenic concentration of the solution containing arsenic is measured at a photometric time in which measurement variation of arsenic is 0.025 mg / l or less. Method. In the high frequency inductively coupled plasma optical emission spectrometry method for a solution containing arsenic, a liquid having a pH of 6 or more and 8 or less is passed through the measurement sample introduction part through which the measurement sample of the high frequency inductively coupled plasma emission spectrometer is passed. And measuring the arsenic concentration of the solution containing arsenic for a photometric time in which the measurement variation is 0.025 mg / l or less.

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