JPH10227778A - Determination method for dibutyl phosphate and monobutyl phosphate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a determination method for determinating DBP(dibutyl phosphate) and MBP(monobutyl phosphate) included in an organic solvent including TBP(tributyl phosphate) by 0.1mg/l. SOLUTION: In the determination of DBP and MBP in an organic solvent by using an ion chromatography, a small amount of alkali solution is brought into contact with the organic solvent, the obtained alkali solution is passed through a cation exchange resin, and the quantity of DBP and MBP in the solution obtained by adsorbing and removing the alkali metal ion in the solution by the ion exchange resin is measured by an ion chromatographic device. The pH of the alkali solution is preferably 12-14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to dibutyl phosphate (hereinafter referred to as "DBP") in an organic solvent containing tributyl phosphate (hereinafter referred to as "TBP").
And a method for quantifying monobutyl phosphate (hereinafter referred to as “MBP”).

[0002]

2. Description of the Related Art TBP in an extracted organic substance used in a reprocessing step of spent nuclear fuel is converted into DB by contact with a radioactive element.
Decomposed into P and MBP. The use of an extracted organic substance containing these substances lowers the extraction rate of the target element. Therefore, it is necessary to control the concentration of the target element to 0.1 mg / l or less.

[0003] Incidentally, methods for analyzing DBP and MBP include a method of methylating DBP and measuring it by gas chromatography (hereinafter referred to as "GC method"), an ion chromatography method using ion exchange separation (hereinafter referred to as "GC method"). "IC
Law ". ).

However, in the GC method, the pretreatment is complicated and time-consuming, and the lower limit of quantification is 10 mg.
Higher enrichment is required, two orders of magnitude higher than / l and the target value. On the other hand, for the IC method, D in an organic solvent is used.
BP needs to be extracted into the aqueous phase. The lower limit of quantification is 1m
g / l, which is not as good as the GC method, but also requires a concentration operation.

[0005]

SUMMARY OF THE INVENTION Due to these problems,
0.1 m for DBP and MBP in an organic solvent containing TBP
Development of a method capable of quantification down to g / l has been awaited. However, a quantitative method for solving such a problem has not yet been put to practical use.

[0006]

Means for Solving the Problems The present inventor has made various studies to solve the above-mentioned problems, and found that the object can be achieved by improving the preprocessing method of the IC method, and reached the present invention.

That is, in the method of the present invention for solving the above-mentioned problems, when quantifying DBP and MBP in an organic solvent by IC method, first, a small amount of an alkaline solution is brought into contact with the organic solvent, The solution is passed through a cation exchange resin, and the amounts of DBP and MBP in the solution obtained by adsorbing and removing alkali metal ions in the solution from the ion exchange resin are measured by an ion chromatograph.
The pH of the alkaline solution is preferably set to 12 to 14.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the method of the present invention, as a pretreatment, an organic solvent is brought into contact with a small amount of an alkaline solution, and DBP and MBP are transferred to an aqueous phase.
This is because an aqueous solution is required to measure these by the method C. And the target lower limit of quantification is 0.
This is because concentration is necessary because the concentration is 1 mg / l. That is, DBP and MBP are concentrated 10 times,
In addition, alkali extraction is most suitable for preparing an aqueous solution. For example, if the amount of the alkaline solution used for 20 ml of the organic solvent is 2 ml, the concentration can be easily increased 10 times.

The alkaline solution used for extraction has a pH of 12
A water-soluble alkali that can be adjusted to ~ 14 is preferred. Preferably, sodium hydroxide is optimal.

The reason why the pH of the alkaline solution is optimally in the range of 12 to 14 is that DBP and MBP in the organic solvent can be extracted by 95% or more in a single extraction operation only in this range. When the pH is 12 or less, the number of extractions for extracting a sufficient amount increases, and the target lower limit of quantification cannot be obtained. On the other hand, when the pH is 14 or more, the concentration of sodium in the measurement solution becomes high, and the measurement by the IC method becomes difficult. When the solution is diluted in order to avoid the difficulty of the measurement by the IC method, the lower limit of quantification becomes worse.

Next, the alkali solution from which DBP and MBP have been extracted is passed through a cation exchange resin. This is because the retention time of cations in the solution overlaps with that of DBP during measurement by the IC method. Is difficult. It should be noted that even when an alkali solution is passed through a cation exchange resin, DBP
And MBP losses are negligible.

[0012]

Next, the present invention will be further described with reference to examples.

Example 1 A sample solution A was obtained by adding DBP and MBP to n-dodecane containing 30% TBP at a concentration of 1 mg / l each.

20 ml of this sample solution A is placed in seven separating funnels, and the pH is adjusted to 1 with sodium hydroxide solution.
1.0, 11.7, 12.0, 13.0, 13.7, 1
2 ml of the alkaline solution adjusted to 4.0 and 14.7 was added to each, and the mixture was shaken with a shaker for 20 minutes. After standing for 20 minutes, only the alkali solution was separated and collected, and the entire amount was washed with a cation exchange resin (product name: LiChrolut SC manufactured by MERCK).
X). The resulting solutions A1, A2, A3, A4,
DBP and MBP in A5, A6, and A7 were quantified using an ion chromatograph analyzer. The measurement was performed using an ion chromatograph analyzer manufactured by Yokogawa Electric Corporation.

The value obtained by dividing the content of DBP and MBP in the obtained solution by the content of DBP and MBP in the sample solution was defined as the recovery rate. The results are shown in Table 1. From these results, in the pH range of 12 to 14, the recovery of DBP and MBP in the obtained solution was almost 100%, indicating that the present method is effective for the quantification of DBP and MBP.
A7 could not be quantified due to cation interference.

[0016] (Example 2) A recovery test was performed in the same manner as in Example 1 except that a potassium hydroxide solution was used instead of the sodium hydroxide solution.

The recovery of DBP and MBP in the obtained solution was 100 in the pH range of 12 to 14 as in Example 1.
%, Which indicates that this method is effective for quantification of DBP and MBP.

Example 3 DBP and M were added to an actual sample solution.
BP was added at 0, 0.1 and 0.5 mg / l, respectively, to obtain sample solutions B, C and D.

20 ml of each of the sample solutions B, C and D was taken into a separating funnel, 2 ml of an alkali solution adjusted to pH 13 with sodium hydroxide solution was added, and the mixture was shaken with a shaker for 20 minutes. After standing for 20 minutes, only the alkaline solution was separated, and the whole amount was passed through a cation exchange resin. And DBP and MBP of the obtained solution were quantified. For the measurement, an ion chromatograph analyzer manufactured by Yokogawa Electric Corporation was used. The content of DBP and MBP in the obtained solution was
The value divided by the sample amount was defined as the quantitative value. Table 2 shows the quantitative results.
It was shown to. The results show that the lower limit of quantification is 0.1 mg / l, indicating that the present method is effective for quantification of DBP and MBP.

[0020] (Comparative Example 1) A recovery test was conducted in the same manner as in Example 1 without passing through a cation exchange resin.

The DBP and MBP of the obtained solution were measured. However, it was difficult to quantify each of the solutions due to interference of a large amount of cations and the like.

[0022]

According to the present invention, DBP and MBP in an organic solvent containing TBP can be determined up to 0.1 mg / l.
Specifically, it may be used as an index for determining the degree of deterioration of the organic solvent used in the reprocessing step of spent nuclear fuel or for washing and reusing the deteriorated organic solvent. it can.

Claims (2)

[Claims] When quantifying dibutyl phosphate and monobutyl phosphate in an organic solvent containing tributyl phosphate using an ion chromatograph analyzer, the organic solvent and a small amount of an alkali solution are used. Contacting, passing the alkaline solution through a cation exchange resin, separating and concentrating dibutyl phosphate and monobutyl phosphate, and then analyzing the dibutyl phosphate and monobutyl phosphate by an ion chromatograph. Assay method. 2. The method for quantifying dibutyl phosphate and monobutyl phosphate according to claim 1, wherein the pH of the alkaline solution is 12 to 14.