Five-step iodometric method

A technology of iodometric method and potassium iodide, which is applied in the field of disinfectant detection, can solve the problems of less risk, inconvenience to carry, and long process time for nitrogen gas.

Inactive Publication Date: 2016-03-16
SHENZHEN SINSCHE TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] For this reason, the technical problem to be solved by the present invention is that the third step in the traditional five-step iodometric method needs to feed high-purity nitrogen, but hi...

Method used

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Embodiment 1

[0025] Present embodiment provides a kind of five-step iodometric method, and it comprises the steps:

[0026] 1) Mix 5ml of the sample to be tested with 200ml of water and adjust the pH to 7 with an appropriate amount of phosphate buffer solution (if the pH of the sample is less than 3, first adjust the pH to greater than 3 with sodium hydroxide solution), add 10ml of 100g / L After the potassium iodide solution, titrate with a sodium thiosulfate standard solution with a concentration of 0.01mol / L until the mixed solution turns light yellow, add 1ml of a starch solution with a concentration of 5g / L, the solution turns blue, continue to titrate thiosulfuric acid Sodium standard solution until the blue color disappears, the volume of the added sodium thiosulfate standard solution is recorded as V1, and V1 is 11.67ml in the present embodiment;

[0027] 2) Gradually add 2ml of hydrochloric acid solution with a concentration of 2.5N to the solution obtained in step 1), adjust the mi...

Embodiment 2

[0053] Present embodiment provides a kind of five-step iodometric method, and it comprises the steps:

[0054] 1) Mix 2ml of the sample to be tested with 50ml of water and adjust the pH to 7 with an appropriate amount of phosphate buffer solution (if the pH of the sample is less than 3, first adjust the pH to greater than 3 with sodium hydroxide solution), add 8ml of 100g / L After the potassium iodide solution, titrate with a standard solution of sodium thiosulfate with a concentration of 0.01mol / L until the mixed solution turns light yellow, add 0.8ml of a starch solution with a concentration of 5g / L, the solution turns blue, and continue to titrate the thiosulfate solution. Sodium sulfate standard solution until the blue color disappears, the volume of the added sodium thiosulfate standard solution is recorded as V1, and V1 is 4.67ml in the present embodiment;

[0055] 2) Gradually add 2ml of hydrochloric acid solution with a concentration of 2.5N to the solution obtained in ...

Embodiment 3

[0067] Present embodiment provides a kind of five-step iodometric method, and it comprises the steps:

[0068] 1) Mix 5ml of the sample to be tested with 300ml of water and adjust the pH to 7 with an appropriate amount of phosphate buffer solution (if the pH of the sample is less than 3, first adjust the pH to greater than 3 with sodium hydroxide solution), add 20ml of 100g / L After the potassium iodide solution, titrate with a standard solution of sodium thiosulfate with a concentration of 0.1mol / L until the mixed solution turns light yellow, add 1.5ml of starch solution with a concentration of 5g / L, the solution turns blue, and continue to titrate the thiosulfate solution. Sodium sulfate standard solution until the blue color disappears, the volume of the added sodium thiosulfate standard solution is recorded as V1, and V1 is 1.17ml in the present embodiment;

[0069] 2) Gradually add 5ml of hydrochloric acid solution with a concentration of 2.5N to the solution obtained in t...

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Abstract

The invention discloses a five-step iodometric method. According to the invention, in the third step of a conventional five-step iodometric method, solution pH value is adjusted to be 12 or higher instead of adding high-purity nitrogen, so that chlorine dioxide in a sample to be detected is transformed into a chlorite and chlorate which are not reacted, separation of chlorine dioxide with chlorine gas is realized, it is not necessary to blow chlorine dioxide and chlorine gas away with high-purity nitrogen, and problems that nitrogen blowing time is controlled to be longer than 40min, treatment time is too long, nitrogen is not easily available, is not convenient to carry, and is dangerous are solved; and in the fourth step, solution pH value is adjusted to be 3 to 7.

Description

technical field [0001] The invention belongs to the technical field of disinfectant detection, in particular to a five-step iodometric method. Background technique [0002] The five-step iodometric method utilizes the I - The degree of reduction of various oxidative chlorines varies with the pH value, and the free I is titrated with sodium thiosulfate standard solution 2 In order to distinguish various chlorides, the five-step iodometric method can simultaneously measure ClO in the sample by controlling the pH during the measurement process. 2 , ClO 2- , ClO 3- and Cl 2 content, and the equipment used is simple, and it has been used as a standard method for evaluating the technical indicators of chlorine dioxide generators in the "Disinfection Technical Specifications". [0003] The specific operation of the five-step iodometric method is: (1) mix a certain amount of pure water, a sample to be tested, and an appropriate amount of phosphate buffer solution to ensure that...

Claims

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Application Information

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IPC IPC(8): G01N31/16
CPCG01N31/16
Inventor 阮建明
Owner SHENZHEN SINSCHE TECH
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