Preparation method of water content standard material

A standard substance and moisture technology, applied in the preparation of test samples, etc., can solve problems such as unevenness between bottles, rapid decrease in moisture content, unstable moisture content, etc., to improve repeatability and accuracy, and to achieve small differences in moisture content , Good uniformity between bottles

Inactive Publication Date: 2011-11-23
NAT INST OF METROLOGY CHINA
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Saturated solutions of water based on other organic solvents, such as saturated xylene solutions of water (moisture content 0.027%), all appear to reduce the phenomenon of moisture content rapidly during use, which is not conducive to the repeated measurement of moisture standard substances when used
On the other hand, the moisture content of the standard substance is unstable, which may easily lead to unevenness between bottles during the preparation of the standard substance, which is not conducive to the accurate determination of the moisture content of the standard substance
Therefore, the saturated solution of water has obvious disadvantages as a moisture standard substance.

Method used

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  • Preparation method of water content standard material
  • Preparation method of water content standard material
  • Preparation method of water content standard material

Examples

Experimental program
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Effect test

Embodiment 1

[0046] Prepare a moisture standard substance with a moisture content of 1%. The mass percentage of propylene carbonate is 55%; the mass percentage of 1-butanol is 27%; and the mass percentage of m-xylene is 18%. The total mass of the mixed solution is 4500g. Karl Fischer coulometric moisture titrator measured the moisture content of the mixed solution to be 0.0156%. The moisture content target value of the moisture standard substance is 1%, and according to formula 2, it is calculated that 44.75 g of water needs to be added. 44.76 g of water was actually added. After the solution is mixed evenly, take 10mL each time to monitor the change of moisture content under different humidity conditions. The result is as figure 1 As shown, when the humidity is 45%, the change value of the sample moisture within 3 hours is less than 0.01%. Adjust the humidity in the fume hood to 45%, and keep it stable for more than 1 hour. In the fume hood, divide the solution in the volumetric flas...

Embodiment 2

[0052] Prepare a moisture standard substance with a moisture content of 0.1%. The mass percentage of propylene carbonate is 49%; the mass percentage of 1-butanol is 0%; the mass percentage of m-xylene is 51%. The total mass of the mixed solution is 4500g. Karl Fischer coulometric moisture titrator measured the moisture content of the mixed solution to be 0.015%. The moisture content target value of the moisture standard substance is 0.1%, and according to formula 2, it is calculated that 3.86 g of water needs to be added. 3.90 g of water was actually added. After the solution is mixed evenly, take 10mL each time to monitor the change of moisture content under different humidity conditions. The result is as figure 2 As shown, when the humidity is 20%, the change value of the sample moisture within 3 hours is less than 0.001%. Adjust the humidity in the fume hood to 20%, and keep it stable for more than 1 hour, and divide the solution in the volumetric flask into ampoules ...

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Abstract

The invention relates to a preparation method of a water content standard material. The method comprises the steps of: weighing the mass of a dried glass volumetric flask, adding propylene carbonate, 1-butanol and xylene in proportion, and weighing the mass of the mixed solution; measuring water in the mixed solution, and calculating the mass of water needing to be added according to a preparation target value; adding deionized water into the volumetric flask and mixing the solution well; shifting part of the mixed solution into an ampoule bottle, adjusting the humidity of a constant temperature and humidity chamber, monitoring water content variations over time under different humidity conditions; recording the humidity within the constant temperature and humidity chamber when the solution water content varies minimally; under a humidity condition with stable solution water content, charging ampoule bottles with the mixed solution separately, and sealing the ampoule bottles; taking the mean of the results measured by Coulometry and volumetric methods as the water content of a standard material; and evaluating the water uncertainty. The water content standard material prepared by the method of the invention is beneficial for improving the accuracy of a Karl Fischer water titrator measuring result.

Description

technical field [0001] The invention relates to a preparation method, in particular to a preparation method of a water content standard substance. Background technique [0002] Moisture widely exists in solid and liquid substances, and accurate measurement of moisture is very important for product quality evaluation and control. The Karl Fischer method is a specific method for moisture, which has the characteristics of good repeatability, high accuracy, convenience and quickness, so it is widely used in medicine, chemical industry, food and light industry and other industries. [0003] Moisture standard substances are used in the calibration and verification of Karl Fischer moisture titrators to ensure accurate and reliable values. In the moisture measurement standards formulated by the International Organization for Standardization (ISO), the American Society for Testing and Materials (ASTM) and relevant domestic units, such as the general measurement standard for moisture...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N1/28G01N1/38
Inventor 王海峰马康张伟李佳孙国华
Owner NAT INST OF METROLOGY CHINA
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