WO2014104652A1

WO2014104652A1 - Quantitative analysis method for molecular iodine contained in iodide compound

Info

Publication number: WO2014104652A1
Application number: PCT/KR2013/011894
Authority: WO
Inventors: 류승원; 차일훈; 김종철; 이지윤; 김민정; 이세호
Original assignee: 에스케이케미칼주식회사
Priority date: 2012-12-26
Filing date: 2013-12-19
Publication date: 2014-07-03
Also published as: KR101929508B1; KR20140083455A

Abstract

The present invention relates to a quantitative analysis method for molecular iodine (I2) in an iodide compound. More particularly, each portion of molecular iodine and iodide ion in a small amount of iodine contained in an iodine compound may be detected by: a step of titrating a first solution obtained by reacting an iodide compound containing molecular iodine (I2) with sodium thiosulfate (Na2S2O3) by means of ionic chromatography and detecting a first concentration of iodide ions (I-) in the first solution; a step of titrating a second solution obtained by reacting an iodide compound containing molecular iodine (I2) with water by means of ionic chromatography and detecting a second concentration of iodide ions (I-) in the second solution; and obtaining the amount of the molecular iodine contained in the iodide compound by subtracting the second concentration from the first concentration.

Description

【Specification】

[Name of invention]

Method for Determination of Molecular Iodine in Iodide Compound

The present invention relates to a method for quantifying the molecular iodine (Iodine, 1 ₂ ) contained in the iodide compound. More specifically, the present invention relates to a method for quantitative determination of iodine in which trace amounts of molecular iodine and iodine anion are precisely measured among trace amounts of iodine present in the iodide compound.

[Technique to become background of invention]

Conventionally, the analysis of molecular iodine has been carried out by using the iodine titration method, the iodine titration method was limited to be measured when the molecular iodine content in the sample to the level of several hundred mg / kg (ppm). Therefore, when the iodine compound containing a small amount of molecular iodine in a few ppm level is quantified by the iodine titration method, there is a limit that the error is large and the accuracy is low and the reliability of the measurement result is not high.

In addition, according to the previously known iodine titration method, there was a limitation in separating the molecular iodine and iodine ions among the iodine present in the iodide compound to precisely quantify the content.

Therefore, the development of a method for quantitative determination of iodine capable of precisely measuring the content of molecular iodine (Iodine, 1 ₂ ) and iodine negative (Iodide) among the trace amounts of iodine contained in the iodide compound is required. It is becoming. [Content of invention]

Problem to be solved

The present invention is to provide a method for quantifying iodine which can precisely measure the content of each of molecular iodine and iodine anion in trace amounts of iodine contained in the iodide compound. [Measures of problem]

The present invention relates to an iodide compound containing molecular iodine (I ₂ , Iodine) and a first solution in which sodium thiosulfate (Ν¾) is reacted by ion chromatography, and the iodine ion (Γ) in the first solution is titrated. Measuring the first concentration of Iodide); An iodide compound containing molecular iodine (I ₂ , Iodine) and a second solution in which water was reacted were titrated by ion chromatography to measure a second concentration of iodide (Γ, Iodide) in the second solution. step; And a method of quantifying molecular iodine obtained by subtracting the second concentration from the first concentration as the content of molecular iodine contained in the iodide compound. Hereinafter, a method for quantifying molecular iodine according to a specific embodiment of the present invention will be described in more detail.

According to one embodiment of the present invention, the first solution obtained by reacting a iodide compound containing molecular iodine (12, Iodine) with sodium thiosulfate (Na ₂ S ₂ 0 ₃ ) is titrated by ion chromatography, Measuring a first concentration of iodine ions (1— ， Iodide) in the first solution; An iodide compound containing molecular iodine (1 _2, Iodine) and a second solution that reacted with water were titrated by ion chromatography to measure the second concentration of iodine ions (Γ, Iodide) in the second solution. step ; And a method of quantitating molecular iodine, wherein the value obtained by subtracting the second concentration from the first concentration is obtained as the content of molecular iodine contained in the iodide compound.

The iodide ion (1-, Iodide) The first and second terms of the concentration is to be used to identify the concentration of the ^iodine, an iodine compound Chemistry ions produced by banung the particular material, the analysis banung sequence or other restrictions It doesn't work. The present inventors have recognized the limitations of the detection limits of several hundred ppm, which the conventional iodine titration method has, and in order to solve this problem, the present inventors have studied a method for quantifying trace amount of molecular iodine (I ₂ , Iodine) contained in an iodide compound Proceeding, the solution in which the iodide compound and the specific compound are reacted is ionized. Analysis by chromatography confirmed that the content of molecular iodine present in trace amounts in the iodide compound can be measured, and the invention was completed.

In particular, in the iodide compound, iodine coexists in the state of molecular iodine (1 ₂ , Iodine) and iodine negative (Γ Iodide), there is a limit to measure each content precisely, previously iodide There is no known quantitative method which can easily measure the content of molecular iodine contained in the compound.

In the method for quantifying molecular iodine, the iodide compound containing molecular iodine (I ₂ , Iodine) is reacted with sodium thiosulfate and water, respectively, and the concentration of iodine ions is measured by subsequent chromatography. The content of molecular iodine contained in the iodide compound can be obtained.

The iodide compound includes both iodides of metals and iodides of nonmetals, and may also include iodides of various hydrocarbons including alkyl. In particular, the iodide compound may be an iodide aryl compound which is an aryl group in which one or more iodine is substituted, and specific examples of the aryl group may include benzene or naphthalene. More preferably, it may be diiodine benzene, benzene iodide or naphthalene iodide.

A first solution of the reaction of an iodide compound with sodium thiosulfate (Na ₂ S ₂ O ₃ ) may be titrated by ion chromatography to determine the first concentration of iodine ions (Γ, Iodide) in the first solution. have. In the measurement of the first concentration, the molecular iodine, which is not in an anionic state, is reacted with sodium thiosulfate to be reduced to an ionic state and titrated by ion chromatography. That is, sodium thiosulfate may serve to reduce molecular iodine present in the iodide compound to generate iodine ions. Therefore, the first concentration of the iodine ion includes both the content of iodine ions present in the iodide compound before reacting with sodium thiosulfate and the molecular iodine reduced by sodium thiosulfate.

The iodide compound and sodium thiosulfate are preferably reacted in a weight ratio of 1: 5 to 1:20, and more preferably in a weight ratio of 1: 7 to 1:15. Reaction amount of the sodium thiosulfate iodide compound When less than 5 times compared to the reaction, the iodide compound is excessive compared to sodium thiosulfate, and molecular iodine cannot be reduced to all iodine ions, which may cause an error in the determination of molecular iodine content. In addition, when the reaction amount of sodium thiosulfate exceeds 20 times that of the iodide compound, the sodium thiosulfate peak is very high upon titration by ion chromatography, and the base line becomes high, making it difficult to measure the peak of the trace amount of iodine ion. . In addition, when the reaction amount of sodium thiosulfate is more than 20 times greater than that of the iodide compound, a trace amount of molecular iodine to be quantified in the iodide compound may be diluted to obtain an incorrect value.

The sodium thiosulfate may have a molar concentration of 0.0005M to 0.002M, or a concentration of 0.0009M to 0.0012M, or about 0.001M. When using sodium thiosulfate at a concentration exceeding 0.002M, the peak of sodium thiosulfate is very high during ion chromatography measurement, making it difficult to measure the peak of trace amount of iodine. In addition, when sodium thiosulfate of less than 0.0005M is used, the reaction of the iodide compound is excessive compared to sodium thiosulfate, and thus, molecular iodine cannot be reduced to iodine. Therefore, an error may occur in the determination of molecular iodine content.

In addition, the step of measuring the first concentration of iodine ions, the concentration of iodine ions contained in sodium thiosulfate by ion chromatography by separating the sodium thiosulfate layer in the first solution of the iodide compound and sodium thiosulfate reaction It can be measured. When the sodium thiosulfate layer is measured separately, the experimental error is reduced, and the subsequent chromatographic titration can be efficiently performed.

Then, the second solution in which the iodide compound and water are reacted is titrated by ion chromatography, and the second concentration of iodine ions (Γ, Iodide) in the second solution can be measured. Molecular iodine (I _2. Iodine) is not only soluble in water, but even when dissolved, it does not ionize through reaction with water, so it exists in molecular iodine (I ₂ , Iodine) state.

Therefore, the second concentration of iodine ions determined by ion chromatography titrating a second solution in which the iodide compound and water are reacted is determined by using water and The content of iodine ions (Γ, Iodide) present in the iodide compound was measured before the reaction.

The iodide compound and water are preferably reacted at a weight ratio of 1: 5 to 1:20, and more preferably at a weight ratio of 1: 7 to 1:15. When the reaction amount of water is less than five times that of the iodide compound, the reacting iodide compound is excessive compared to water, and molecular iodine cannot be reduced to all iodine ions, which may cause an error in the determination of molecular iodine content. In addition, when the reaction amount of water exceeds 20 times that of the iodide compound, a very small amount of molecular iodine to be quantified in the iodide compound may be diluted to obtain an inaccurate value.

Distilled water, ultrapure water, purified water, and the like may be used as the water, and among them, it is preferable to use ultrapure water of 18.5 ΜΩ or more in order to prevent generation of other ions and to obtain precise experimental results.

In the measuring of the second concentration of iodine ions, the concentration of iodine ions in the water layer may be measured by ion chromatography by separating the water layer from the second solution in which the iodide compound and the water are reacted. have. By separating and measuring the water layer, the experimental error is reduced and the ion chromatography titration can be efficiently performed.

In addition, the first or second solution may further include an organic solvent. As the organic solvent, any iodide compound to be analyzed can be dissolved without affecting the structure or other physical properties of the iodide compound, and any organic solvent which is an organic solvent which is not mixed with water can be used without limitation. Specifically, it is preferable to use a solvent such as benzene, p-Xylene, toluene, and the like. As described above, in the case where the iodide compound is dissolved in an organic solvent and reacted, the iodide compound which is not easily dissolved in water and which is not easily ion titrated through the reaction with sodium thiosulfate or water can be titrated.

The iodide compound and the organic solvent are preferably reacted at a weight ratio of 1: 5 to 1:15. Iodide when dissolved in excess of organic solvent Molecular iodine, which is contained in trace amounts in the compound, is diluted dilutely, making it difficult to accurately determine by ion chromatography.

The value obtained by subtracting the second concentration from the measured first concentration of iodine ions may be obtained as the content of molecular iodine contained in the iodide compound. The first solution may include iodine ions derived from molecular iodine and iodide compounds, and the second solution may include iodine ions derived from non-ionized molecular iodine and iodide compounds.

That is, the first concentration represents the concentration of the molecular iodide and the iodide ion derived from the iodide compound contained in the iodide compound, and the second concentration includes only the iodide ion contained before the iodide compound reacts with water, The difference value of the first concentration minus the second concentration means the concentration of iodine silver derived from the molecular iodine present in the iodide compound. Therefore, the content of iodine ions (Γ, Iodide) contained in the iodide compound can be obtained from the measured second concentration of the iodine silver, and molecular iodine (I _2, Iodine) content can be obtained.

By using the above quantitative method for molecular iodine, the content of molecular iodine and iodine ions can be measured, respectively, and a very small amount of iodine content of O.Olppm level can be measured. In other words, the method for quantifying molecular iodine may quantify molecular iodine of O. Olppm or more contained in the iodide compound.

According to the previously known potentiometric titration method, the molecular iodine contained in the iodide compound could be measured up to 100 ppm level, but the reliability of the measurement result was not high, and there was a limit in which low molecular iodine could not be measured. On the contrary, according to the quantitative method of the embodiment of the present invention, not only the trace amount of iodine content can be measured, but also the same level of results can be obtained even if the quantitative is repeated under the same conditions, so that the reliability of the quantitative result is very high. 【Effects of the Invention】 According to the present invention, the content of each of molecular iodine (I ₂ , Iodine) and iodine ion (1—, Iodide) in the trace amount of iodine contained in the iodide compound can be measured accurately. [Brief Description of Drawings]

1 is a graph and a correlation coefficient for Iodide (peak area) 1 of 1) of Verification Example 1. FIG.

FIG. 2 is a graph and correlation coefficient for Iodide (peak area) 2 of 1) of Example 1. FIG.

,

[Specific contents to carry out invention]

The invention is explained in more detail in the following examples. However, the following examples are merely to illustrate the invention, but the content of the present invention is not limited by the following examples.

Example 1 Determination of Molecular Iodine in Para-Diiodide Benzene

1) measuring the first concentration of iodine ions (Γ, Iodide)

Para-diiodine benzene (lg) was dissolved in p-Xylene (9 g), and the lower layer (sodium thiosulfate layer) of the solution reacted with sodium thiosulfate (Na ₂ S ₂ 0 ₃ , 0.001 M, lOg) Analyzed by ion chromatography (Dionex ICS-5000). Ion chromatography was performed using IonPac® AG11-HC (2 瞧 x 50 腿), AS11-HC (2 匪 x 250 腿) columns, 0.35 ml / min Flow rate, 50 m Injection Volume, Column temperature 30 ^° C, and Cell were measured the first concentration of iodine ions under the conditions of 35 ^° C.

2) measuring the second concentration of iodine silver (Γ, Iodide)

The second concentration of iodine ion was measured in the same manner as in the step of measuring the first concentration except that distilled water was used instead of sodium thiosulfate (Na2S203, O.OOIM).

3) Determination of Iodine in Para-Diiodide Benzene Molecular iodine (1 ₂ , Iodine) content of para-diiodide benzene was obtained by subtracting the second concentration from the first concentration of iodine ions.

Repeating the steps 1) to 3) three times, the average value reflecting the dilution factor is shown in the measurement concentration up to the first decimal place in Table 1, rounded off from the second decimal place, and the molecular weight as a difference between the two decimal places. After determining the content of iodine, it was written down to the first decimal place in the content of iodine.

[Table 1]: Para-diiodide benzene sample analysis result (unit: mg / kg)

[Example 2]: Determination of molecular iodide (I ^ odiiie) in benzene iodide Beneficial determination of molecular iodine was carried out in the same manner as in Example 1 except that benzene iodide (lg) was used instead of paradecidiodidebenzene (lg). It was.

Example 3 Determination of Molecular Iodine (Ig _^ Iodine) in Naphthalene Iodide The molecular weight of iodine was determined in the same manner as in Example 1 except that naphthalene iodide (lg) was used instead of para-diiodic benzene (lg). It was. The concentration of iodine ions and the content of molecular iodine measured in Examples 2 to 3 are shown in Table 2 below.

[Table 2]: Results of analysis of benzene iodide and naphthalide iodide (unit mg / kg)

As shown in Table 1, the results of the analysis of the molecular iodine and iodine ion content in the parabendi iodide benzene, the molecular iodine was found to contain 0.8 to 4.4 mg / kg, the iodine is 0.9 to 2.3 It was shown to contain mg / kg.

In addition, as can be seen in Table 2, the content of molecular iodine and iodine ion of the banyan iodide appeared 2.2 and 0.1 mg / kg, the content of molecular iodine and silver iodine of naphthalene iodide, also 16.2 And 9.9 mg / kg.

Therefore, it was confirmed from the results of Examples 1 to 3 that the quantitative method of molecular iodine can be measured up to several ppm concentration, which is remarkably improved compared to the iodine titration method, which was only capable of analyzing the concentration of several hundred ppm in the past. As a result, it is possible to measure the trace amount of iodine at the lowest O.Olppm. [Validation Example 1]: Validation of the experimental method

1) Linearity

It is proved that the concentration of the analyte and the measurement result are in proportional relationship at the concentration of the application range. It is represented by the linear correlation coefficient (R ² ), and when the R ² is 0.99 or more, the concentration of the analyte and the measurement result are It can be said. Using the standard of iodine ion, the peak area of iodine ion was obtained for 7 standard concentrations in the concentration range of 01 to 30.0 mg / kg, and the content of silver iodine was measured. 1 and FIG. 2. [Table 3] Correlation coefficient for peak area of iodine ion standard (R ² )

2) Precision

As a measure of the degree to which the values measured several times under the same conditions are expressed as relative standard deviation (% RSD) for repeated measurements, precision can be evaluated for experiments with% RSD of 5% or less.

In the low concentration range indicating linearity, the peak area was repeatedly measured five times for each standard, and the relative standard deviation, ° h RSD, was calculated and shown in Table 4 below.

Table 4: Relative standard deviation of peak area of iodine ion standard (%

RSD)

3) Accuracy

By evaluating the closeness of the true value to the measured value, an experiment showing the recovery of the measured value against the certified value of the molecular iodine standard and having a recovery range of 90% to 110% can be evaluated as accuracy. Molecular iodine standards were prepared for each concentration, and each was analyzed by ion chromatography (IC), and the accuracy (recovery rate) was evaluated by comparing the analysis result with the production concentration of the molecular iodine standard. The molecular iodine standard was repeatedly titrated five times in the concentration range of 1.0 mg / kg to 40.0 mg / kg, and the result reflecting the pluripotency was rounded to two decimal places in Table 5 below. Molecular iodine content was determined by the difference of the decimal place of two digits, and the molecular iodine content was entered up to the first decimal place.

[Table 5] Analysis recovery rate of molecular iodine standards by concentration

* The measurement concentration and the content of molecular iodine are described in half, and the recovery rate was obtained based on actual measurements. In 1) of the verification example 1, the correlation coefficient (R ² ) of the straight line was found to be 0.999 or more, so that the concentration of the standard material after iodine and the peak area of the iodine ion in the actual ion chromatography were proportional to each other. The linearity of the method was confirmed. In addition, the relative standard deviation with respect to the peak area of the iodine ion standard in 2) is shown to be less than 5%, it was confirmed that the experimental method of the example has a precision (Precision).

In addition, in 3), the molecular weight of the iodine standard was prepared for each concentration (1.0 mg / kg to 40.0 mg / kg) to confirm the accuracy (recovery rate), and the correlation coefficient (R ² ) of the linear line for each iteration was also confirmed. All four repetitions showed a recovery rate within 92 to 107% to confirm the accuracy of the experimental method of the example. And it was confirmed that all four repetitions showed a result with a correlation coefficient (R ² ) of 0.999 or more, and with linearity with the result of 1).

Therefore, the experimental method of the embodiment was found to be effective by producing results higher than the parameter criteria in all items such as linearity, accuracy and precision.

Verification Example 2 Detection Limit (L0D) and Quantitative Limit (L0Q)

Limits of detection for the test method (analysis conditions)

Detect ion) was used as the detection limit (L0D) for the instrument using the results of the precision experiment conducted above to determine the lowest concentration of the analyte that can be clearly distinguished from "0". Limits of Quantitation (L0Q) was set to three times the limit of detection (L0D), which is generally recommended. Method detection limit (MDL) indicating the detection limit for the test method was calculated in consideration of the weight of the sample and the dilution factor during pretreatment.

TABLE 6 LOD, LOQ, MDL for test methods

Claims

Patent Claim

[Claim 11

The first solution in which the iodide compound containing molecular iodine (I _2, Iodine) was reacted with sodium thiosulfate (Na ₂ S ₂ 0 ₃ ) was titrated by subsequent chromatography, and the iodine ion in the first solution was titrated. Measuring a first concentration of (Γ, Iodide);

An iodide compound containing molecular iodine (I _2, Iodine) and a second solution containing water were titrated by ion chromatography to measure the second concentration of iodine ions (Γ, Iodide) in the second solution. step ; And

A method for quantifying molecular iodine, wherein the value obtained by subtracting the second concentration from the first concentration is obtained as the content of molecular iodine contained in the iodide compound.

[Claim 2]

The method of claim 1,

The iodide compound is a method for quantifying molecular iodine is an aryl iodide compound.

[Claim 3]

The method of claim 1,

Wherein said iodinated compound is at least one iodine substituted benzene or naphthalene.

[Claim 4]

The method of claim 1,

The iodide compound is a method for quantifying molecular iodine is diiodine benzene, iodide benzene or iodide naphthalene.

[Claim 5]

The method of claim 1, A method for quantifying molecular iodine by reacting the iodide compound and sodium thiosulfate in a weight ratio of 1: 5 to 1:20.

[Claim 6]

The method of claim 1,

Wherein said sodium thiosulfate has a molar concentration of 0.0005M to 0.002M.

[Claim 7]

The method of claim 1,

In the measuring of the first concentration, the sodium thiosulfate layer is separated from the first solution and ion chromatography (Io) ion (Γ, Iodide) contained in the sodium thiosulfate layer is measured, the method of quantitative molecular iodine.

[Claim 8]

The method of claim 1,

A method for quantifying molecular iodine by reacting the iodide compound and water in a weight ratio of 1: 5 to 1:20.

[Claim 9]

The method of claim 1,

In the measuring step of the second concentration ᅳ separating the water layer in the second solution and then measuring the concentration of iodine ion (Γ, Iodide) contained in the water layer by chromatography, quantitative method of molecular iodine.

[Claim 10]

The method of claim 1 The first or second solution is a method for quantifying molecular iodine comprising at least one organic solvent selected from the group consisting of p-Xylene, benzene, Toluene. [Claim 11]

The method of claim 10,

Wherein said first or second solution comprises said iodide compound and said organic solvent in a weight ratio of 1: 5 to 1:15.