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Method for measuring ethoxy content of ethyl cellulose by using headspace gas chromatography

A headspace gas chromatography and ethyl cellulose technology, applied in the direction of measuring devices, instruments, scientific instruments, etc., can solve the problems of inaccurate manual extraction, corrosion, and easy to cause errors, etc., to improve sensitivity and repeatability, analyze Short time, high accuracy results

Inactive Publication Date: 2011-09-14
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the manual extraction is not accurate enough, the sampling process is easy to cause errors, and a small amount of hydroiodic acid in the sample will cause corrosion of the sampling tube and chromatographic column

Method used

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  • Method for measuring ethoxy content of ethyl cellulose by using headspace gas chromatography
  • Method for measuring ethoxy content of ethyl cellulose by using headspace gas chromatography
  • Method for measuring ethoxy content of ethyl cellulose by using headspace gas chromatography

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] 1. detection method of the present invention is specifically as follows:

[0031] (1) Solution preparation

[0032] Internal standard solution: add 10mL o-xylene to a 100mL volumetric flask, then add 2.5g toluene, and finally dilute to 100mL with o-xylene.

[0033] Standard sample solution: Add 20 mg of adipic acid, 15 mg of cotton linters, 1 mL of internal standard solution, 0.5 mL of 8mol / L NaoH solution, and 0.5 mL of 57% HI solution into the headspace bottle, and seal it. Add 2, 4, 6, 8, 10, 15, and 20 μL of iodoethane to the microsyringe puncture, accurately weigh, record the exact mass of iodoethane added, and sample numbers are 1, 2, 3, 4, 5, 6, 7.

[0034] Sample solution: Add 20 mg of adipic acid, 10 mg of ethyl cellulose (DOW Chemical Company, USA), 1 mL of internal standard solution, and 0.5 mL of 57% HI solution into the headspace vial, and seal it. Weigh the headspace vial and shake the sample for 30 s. The headspace bottle was placed in an incubator at...

Embodiment 2

[0050]Accurately weigh 10 mg of pharmaceutical grade ethyl cellulose sample (Shandong Heda Co., Ltd. batch number 100518003), 5 parts in total, add 20 mg of adipic acid, 1 mL of internal standard solution, and 0.5 mL of 57% HI solution into a headspace vial, and seal it. Weigh the headspace vial and shake the sample for 30 s. The headspace bottle was placed in an incubator at 140°C for 2 h, and the sample was shaken for 30 s every 30 min. Cool to room temperature, weigh again, and make sure there is no leakage. Add 0.5mL of 8mol / L NaOH solution by syringe puncture to neutralize the remaining HI. The results are shown in Table 3. Other steps of this embodiment are the same as in Embodiment 1.

[0051] The above operation was repeated once, and the results obtained are shown in Table 3.

Embodiment 3

[0053] Accurately weigh 10 mg of industrial-grade ethylcellulose sample (Shantai Cellulose Co., Ltd.), 5 parts in total, add 20 mg of adipic acid, 1 mL of internal standard solution, and 0.5 mL of 57% HI solution into a headspace vial, and seal it. Weigh the headspace vial and shake the sample for 30 s. The headspace bottle was placed in an incubator at 140°C for 2 h, and the sample was shaken for 30 s every 30 min. Cool to room temperature, weigh again, and make sure there is no leakage. Puncture the syringe and add 0.5 mL of 8mol / L NaOH solution to neutralize the remaining HI. The results are shown in Table 3. Other steps of this embodiment are the same as in Embodiment 1.

[0054] The above operation was repeated once, and the results obtained are shown in Table 3.

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Abstract

The invention relates to a method for measuring ethoxy content of ethyl cellulose by using headspace gas chromatography. The measuring method comprises the following steps of: hydrolyzing the ethyl cellulose by hydroiodic acid in the presence of an adipic acid catalyst under high-temperature closed conditions, wherein the ethoxy of the ethyl cellulose is converted into iodoethane, o-xylene is used as an absorbent, and the hydrolysis reaction of the ethyl cellulose is complete due to the actions of the catalyst and the absorbent; selecting toluene as internal standard solution, selecting the iodoethane as standard sample solution, performing headspace sampling, and performing gas chromatography; and calculating the ethoxy content of the sample according to the peak areas of the internal standard solution and the standard sample solution. The method is superior to a common chemical titration method, and has the characteristics of short analysis time, simple operation, high accuracy and the like.

Description

Technical field [0001] The invention relates to a method for determining the ethoxy group content of ethyl cellulose using headspace gas chromatography, and belongs to the technical field of physical and chemical testing of fine chemical raw materials. Background technique [0002] Ethyl cellulose (EC) is a thermoplastic nonionic cellulose ether that is soluble in a variety of organic solvents and can still maintain good flexibility at low temperatures. EC has bonding, filling and film-forming functions and is used to synthesize plastics, coatings, inks, insulation materials, etc. Since EC is non-toxic, it is increasingly used in pharmaceutical excipients and food packaging. In particular, EC with high purity and high ethoxy group content is a key component of drug sustained-release controlled tablets. The ethoxy group content determination method is mainly a chemical titration method based on the Zeisel reaction. The ethyl cellulose is heated with hydriodic acid to decomp...

Claims

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Application Information

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IPC IPC(8): G01N30/02
Inventor 付时雨谢传龙
Owner SOUTH CHINA UNIV OF TECH
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