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Method by utilizing all-volatility headspace gas chromatography to measure content of alkoxy

A headspace gas chromatography and alkoxy technology, applied in measuring devices, instruments, scientific instruments, etc., can solve the problems of corrosion, interference, volatile component analysis, etc., to avoid corrosion, save time, and achieve continuity. Effect

Inactive Publication Date: 2012-03-21
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 of the supernatant is easy to be mixed with matrix components such as hydrolyzed products, which will affect and interfere with the analysis of volatile components, and a small amount of hydroiodic acid in the sample will cause corrosion to the injection tube and chromatographic column

Method used

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  • Method by utilizing all-volatility headspace gas chromatography to measure content of alkoxy
  • Method by utilizing all-volatility headspace gas chromatography to measure content of alkoxy
  • Method by utilizing all-volatility headspace gas chromatography to measure content of alkoxy

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] (1) Solution preparation

[0035] Internal standard solution: add 10mL o-xylene to a 100mL volumetric flask, then add 2.5g of toluene, and finally dilute to 100mL with o-xylene.

[0036] Standard solution: Add 20mg of adipic acid, 1mL of internal standard solution, 0.5mL of 8mol / L NaOH solution, and 0.5mL of 57% HI solution to the headspace bottle, and seal. Add 2, 4, 6, 8, 10, 15, 20 μL of methyl iodide to microsyringe puncture, accurately weigh, record the exact added mass of methyl iodide, use microsyringe to draw 30μL of supernatant into the headspace bottle and press the cap Seal, sample numbers 1, 2, 3, 4, 5, 6, and 7 respectively.

[0037] Sample solution: Add 20 mg of adipic acid, 10 mg of methyl cellulose, 1 mL of internal standard solution, and 0.5 mL of 57% HI solution to the headspace bottle, and seal it. Weigh the headspace bottle and shake the sample for 30 seconds. The headspace bottle was placed in a thermostat at 140°C for 2 hours, and the sample was shaken...

Embodiment 2

[0052] The difference between this embodiment and Embodiment 1 is:

[0053] Accurately weigh 10 mg of pharmaceutical grade ethyl cellulose sample (DOW Chemical Company), 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 bottle and seal it. Weigh the headspace bottle and shake the sample for 30 seconds. The headspace bottle was placed in a thermostat at 150°C for 1.5 hours, and the sample was shaken every 30 minutes for 30 seconds. Cool to room temperature and re-weigh to confirm that there is no leakage. Add 0.5 mL of 8mol / L NaoH solution to the syringe to neutralize the remaining HI. Withdraw 30 μL of supernatant into the headspace bottle, press the cap and seal, and analyze by fully volatile headspace sampling, and the measured ethoxy content is 48.7%.

Embodiment 3

[0055] The difference between this embodiment and Embodiment 1 is:

[0056] Accurately weigh 10 mg of pharmaceutical grade hydroxypropyl methylcellulose sample (Shandong Heda 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 the headspace bottle and seal it . Weigh the headspace bottle and shake the sample for 30 seconds. The headspace bottle was placed in a thermostat at 140°C for 2 hours, and the sample was shaken every 30 minutes for 30 seconds. Cool to room temperature and re-weigh to confirm that there is no leakage. Add 0.5 mL of 8mol / L NaoH solution to the syringe to neutralize the remaining HI. Withdraw 20 μL of supernatant into the headspace bottle, press the cap and seal, and analyze by fully volatile headspace sampling. The measured content of methoxy group is 15.8% and the content of hydroxypropoxy group is 22.1%.

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Abstract

The invention relates to a method by utilizing all-volatility headspace gas chromatography to measure content of alkoxy, which can be used for measuring content of alkoxy groups such as methoxyl group, oxyethyl group, propxy group and the like in polymer derivatives. The measurement method comprises the steps that: a test piece containing the alkoxy is hydrolyzed by hydriodic acid by adopting adipate as catalyst under the high-temperature closed condition, the alkoxy is transformed to corresponding methyl iodide, and ortho-xylene is used as an absorbent. Because of the effect of the catalyst and the absorbent, the adequate hydrolysis reaction is promoted, toluene is then adopted as internal standard solution, the corresponding mehyl iodide is used as the standard solution, a micro-liter-level sample is placed inside a headspace bottle, and the all-volatility headspace sampling and gas chromatography is adopted. According to the peak area of the internal standard solution and the standard solution, the content of the alkoxy in the sample is calculated. The method is better than ordinary chemical titration method and gas chromatography and has the characteristics of short analysis time, simplicity in operation, high accuracy and the like.

Description

Technical field [0001] The invention relates to a method for determining the content of alkoxy groups by fully volatile headspace gas chromatography, which belongs to the technical field of physical and chemical inspection of fine chemical raw materials. Background technique [0002] Natural polymer materials such as cellulose have no thermoplasticity and cannot be dissolved in conventional solvents. Through alkylation chemical modification, polymer derivatives containing different alkoxy groups are generated. They are soluble in common solvents such as water and ethanol, and have film-forming properties. , Thermoplasticity and certain mechanical strength. The content of alkoxy groups is directly related to the performance of polymer derivatives, and the method of quickly and accurately determining the content of alkoxy groups is beneficial to the quality monitoring of polymer derivatives. [0003] The conventional method for determination of alkoxy group is chemical titration. Th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N30/02
Inventor 付时雨谢传龙张亮亮
Owner SOUTH CHINA UNIV OF TECH
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