A Novel Method for Determination of Ethoxyl Content in Ethyl Cellulose by Headspace Gas Chromatography

Abstract

This paper reported a headspace gas chromatographic (HS-GC) method for the determination of ethoxyl in ethyl cellulose. A 0.5 mL sample of hydroiodic acid (57%) was added to ∼20 mg samples in a closed headspace test vial (20mL) for 30 min at 120°C, for the quantitative cleavage of ethoxyl with hydroiodic acid (HI) to form ethyl iodide. After the reaction, the excess amount of HI in the vial was neutralized by injecting a sodium hydroxide solution, and then the ethyl iodide in the vial was determined by headspace gas chromatography using a flame ionization detector. The results showed that the method has an excellent measurement precision (RSD <0.5%) and accuracy (recovery = 98.6 ± 0.5%) for the quantification of ethoxyl content in ethyl celluloses. The present method is simple and accurate, which can be used for the efficient determination of ethoxyl substitution in ethyl cellulose related research.

Keywords:

• Ethoxyl
• Ethyl iodide
• Gas chromatography
• Headspace
• Hydroiodic acid

Acknowledgments

This work was supported by the National Basic Research Program of China (973 Program 2007 CB210201), the National Natural Science Foundation of China (21006034, 21076091, and 21037001), and the Innovation Foundation for the Youth Scholars of State Key Laboratory of Pulp and Paper Engineering of South China University of Technology.