Method for improving iodometry measurement accuracy of samples containing interfering substances

An interfering substance, iodometric method, applied in the field of analysis and detection, can solve problems such as difficulty in accurate determination, and achieve the effect of easy operation and less dosage

Active Publication Date: 2016-01-20
广州超威生物科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] The purpose of the present invention is to provide a simple and reliable method to solve the technical problem that some samples are difficult to measure accurately due to turbidity when they are measured by conventional iodometric method

Method used

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  • Method for improving iodometry measurement accuracy of samples containing interfering substances
  • Method for improving iodometry measurement accuracy of samples containing interfering substances
  • Method for improving iodometry measurement accuracy of samples containing interfering substances

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0040] Embodiment 1. Direct iodometric method measures vitamin C in a certain sample

[0041] The normal method is:

[0042] Accurately weigh an appropriate amount of vitamin C-containing sample (or prepare an aqueous solution of appropriate concentration in advance), add appropriate amount of pure water, add 10mL 2mol / L acetic acid and 1mL 1% starch solution, and immediately titrate with 0.05mol / L iodine standard solution to a stable Light blue, no fading within 30 seconds is the end point. Record the volume of iodine standard solution consumed. At the same time, titrate the reagent blank with pure water, and record the volume of iodine standard solution consumed by the blank.

[0043] When the sample contains interfering substances (OA-12), the titration end point is turbid with the above method, and the starch cannot develop color. The following improved methods can be used to solve the problem:

[0044] Accurately weigh an appropriate amount of vitamin C-containing sam...

Embodiment 2

[0045] Embodiment 2. residual iodometric method measures formaldehyde in a certain sample

[0046] The normal method is:

[0047] Accurately weigh an appropriate amount of formaldehyde-containing sample (or prepare an aqueous solution with a suitable concentration in advance), add 20.00mL of 0.1mol / L iodine solution and 15mL of 1mol / L sodium hydroxide solution, and let it stand for 15min. Add 20mL of 0.5mol / L sulfuric acid solution and let it stand for 15min. Titrate with 0.1mol / L sodium thiosulfate standard solution until the solution is light yellow, add 1mL of 0.5% starch solution and continue titrating until the blue just fades as the end point. Record the volume of sodium thiosulfate standard solution consumed. At the same time, titrate the reagent blank with pure water, and record the volume of sodium thiosulfate standard solution consumed by the blank.

[0048] When the sample contains interfering substances (1227), use the above method to titrate the end point to ...

Embodiment 3

[0050] Embodiment 3: the available chlorine of certain disinfectant is measured by displacement iodometric method

[0051] The normal method is:

[0052] Accurately weigh an appropriate amount of chlorine-containing disinfectant (or prepare an aqueous solution with a suitable concentration in advance) in a 100mL iodine bottle, add 10mL of 2mol / L sulfuric acid, 10mL of 100g / L potassium iodide solution, and place in a dark place for 5 minutes. Titrate with 0.1mol / L sodium thiosulfate standard solution until the solution is light yellow, add 10 drops of 5g / L starch solution, continue titrating until the blue color disappears, record the volume of consumed sodium thiosulfate standard solution. At the same time, titrate the reagent blank with pure water, and record the volume of sodium thiosulfate standard solution consumed by the blank.

[0053] When the sample contains interfering substances (OA-12), the titration end point is turbid with the above method, and the starch canno...

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Abstract

The invention discloses a method for improving iodometry measurement accuracy of samples containing interfering substances. According to the method, a proper amount of nonionic surfactant is added on the basis of a conventional iodometry, and the problems that certain samples containing the interfering substances become turbid in the titration testing process and even accurate measurement is difficult due to iodine precipitation are successfully solved. By means of the method, a titration reaction is quick and sufficient, a titration end point is clear and transparent, the end point is accurately judged through color changes of iodine even if starch can not normally display colors, and a test result is good in precision and accuracy. Reagents used in the method are all conventional, safe, free of harm, easy to operate and suitable for being popularized in detection organizations and research institutions.

Description

technical field [0001] The invention relates to a method for improving the measurement accuracy of iodometric method, which can overcome the problem that certain samples containing interfering substances cannot be accurately measured due to turbidity when measured by conventional iodometric method, and belongs to the technical field of analysis and detection. Background technique [0002] Iodometric method uses iodine (I 2 ) Oxidation and iodide ion (I - ) reduction method to carry out titration. There are direct iodometric method and indirect iodometric method. Direct iodometric method is to directly use iodine standard solution (actually I 3 - solution) to titrate the reducing sample, the end point changes from colorless to light yellow (if starch solution is added, it becomes light blue). Indirect iodometric method can be divided into residual iodometric method and displacement iodometric method. The remaining iodine method is to add quantitative and excessive iodin...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N31/16
Inventor 尹齐和许锐芬钱千里吴萍萍黄亮张利萍
Owner 广州超威生物科技有限公司
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