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Reagent for Karl Fischer volumetric method, preparation method of reagent and application of reagent

A technology of Karl Fischer and volumetric method, applied in chemical method analysis, measuring device, chemical analysis by titration method, etc. It can solve the problems of rising instrument drift value, failure of buffer solution, inability to continue testing, etc.

Inactive Publication Date: 2019-03-01
DONGGUAN SHANSHAN BATTERY MATERIALS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

There have been experiments to detect the moisture content of vinyl sulfate by Karl Fischer furnace moisture meter, but since the melting point of vinyl sulfate is only 99°C, if the temperature of the Karl Fischer furnace exceeds 100°C, the sample will be liquefied and the test cannot be continued. If the setting is lower than 100°C, the water cannot be completely vaporized into the titration cell, resulting in low test results and inaccurate results
Later, the coulometric method was used for direct sample injection or sample analysis after solvent dilution, but because vinyl sulfate would slowly react with the hydroxyl group in the coulometric Karl Fischer reagent to produce acid, the pH value in the coulometric Karl Fischer reagent decreased. , which makes the buffer solution of the coulometric Karl Fischer reagent invalid, and the instrument drift value increases, making it impossible to continue the test

Method used

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  • Reagent for Karl Fischer volumetric method, preparation method of reagent and application of reagent
  • Reagent for Karl Fischer volumetric method, preparation method of reagent and application of reagent
  • Reagent for Karl Fischer volumetric method, preparation method of reagent and application of reagent

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Effect test

Embodiment 1

[0021] Embodiment 1: Reagent for Karl Fischer volumetric method

[0022] Karl Fischer volumetric titrant formulation components are:

[0023]

[0024]

[0025] Preparation method of titrant for Karl Fischer volumetric method: add imidazole into N-methylformamide at room temperature, stir and dissolve, add iodine, stir and dissolve again, put the solution in an ice bath (0-10°C ), while stirring, slowly introduce sulfur dioxide gas or add liquid sulfur dioxide until the weight increases to the required weight of sulfur dioxide. After 24 hours in the dark. Put this reagent into the titration bottle of the volumetric Karl Fischer moisture meter as a titrant.

[0026] Solvent formula components for Karl Fischer volumetric method:

[0027] 70 parts of ethylene glycol methyl ether

[0028] 25 parts ethanol

[0029] Imidazole 15 parts

[0030] Preparation method of solvent for Karl Fischer volumetric method: add imidazole into absolute ethanol at room temperature, stir an...

Embodiment 2

[0031] Embodiment 2: Reagents for Karl Fischer Volumetric Method

[0032] Karl Fischer volumetric titrant formulation components are:

[0033]

[0034] Preparation method of titrant for Karl Fischer volumetric method: add imidazole into N-methylformamide at room temperature, stir and dissolve, add iodine, stir and dissolve again, put the solution in an ice bath (0-10°C ), while stirring, slowly introduce sulfur dioxide gas or add liquid sulfur dioxide until the weight increases to the required weight of sulfur dioxide. After 24 hours in the dark. Put this reagent into the titration bottle of the volumetric Karl Fischer moisture meter as a titrant.

[0035] Solvent formula components for Karl Fischer volumetric method:

[0036] 55 parts of ethylene glycol methyl ether

[0037] 25 parts ethanol

[0038] Imidazole 20 parts

[0039] Preparation method of solvent for Karl Fischer volumetric method: add imidazole into absolute ethanol at room temperature, stir and dissolve ...

Embodiment 3

[0040] Embodiment 3: the standardization of reagent for Karl Fischer volumetric method

[0041] Put the moisture meter, the reagent for Karl Fischer volumetric method and the sample to be tested in a drying room with a dew point of -50°C for operation, first put the prepared Karl Fischer volumetric titrant into the instrument, and connect the burette; Put 50-100ml prepared Karl Fischer volumetric method solvent into the titration cup, put it into the instrument, titrate until the solvent is anhydrous, and the instrument drift reaches equilibrium. Use a 5ul micro-sampler to draw 5ul deionized water, and use the subtraction method Weigh, accurate to 0.00001g, start the instrument to calibrate the titer of the titrant, and the deionized water calibration results are shown in Table 1.

[0042] Calibration calculation formula: T=M 水 / V 标 *1000

[0043] Among them: T---the titer mg / ml of Karl Fischer reagent,

[0044] M water---injection volume of water during calibration g

[...

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Abstract

The invention discloses a reagent for a Karl Fischer volumetric method, a preparation method of the reagent and an application of the reagent. The reagent for the Karl Fischer volumetric method comprises a titrant and a solvent, wherein the titrant comprises iodine, sulfur dioxide, N-methylformamide and imidazole, and the solvent comprises ethylene glycol monomethyl ether, ethyl alcohol and imidazole. The titrant and the solvent in the reagent for the Karl Fischer volumetric method is free from methyl alcohol, the ethyl alcohol and the imidazole are added into a reactive solvent, hydroxy needed by Karl Fischer reaction can be ensured, reaction can be normal, reaction of ethylene sulfate and alcohol can be slowed down, even if slight reactant acid is generated, the reactant acid can be neutralized by a large amount of imidazole in the solvent, the PH (potential of hydrogen) value of volumetric solution is buffered, and side reaction is avoided, so that water titration of the ethylene sulfate is realized.

Description

technical field [0001] The invention relates to the field of moisture detection, in particular to a reagent for Karl Fischer volumetric method, a preparation method and application thereof. Background technique [0002] Vinyl sulfate is widely used as an important additive for battery film formation. It is generally required that its moisture content be lower than 200ppm. There have been experiments to detect the moisture content of vinyl sulfate by Karl Fischer furnace moisture meter, but since the melting point of vinyl sulfate is only 99°C, if the temperature of the Karl Fischer furnace exceeds 100°C, the sample will be liquefied and the test cannot be continued. If the setting is lower than 100°C, the water cannot be completely vaporized into the titration cell, resulting in low test results and inaccurate results. Later, the coulometric method was used for direct sample injection or sample analysis after solvent dilution, but because vinyl sulfate would slowly react w...

Claims

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Application Information

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IPC IPC(8): G01N31/16
CPCG01N31/168
Inventor 廖红伟
Owner DONGGUAN SHANSHAN BATTERY MATERIALS
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