Comparative Gas Chromatography Analysis of Ethoxylated Fatty Acid Methyl Esters with Packed and Capillary Columns

摘要

Directly ethoxylated fatty acid methyl esters are an emerging raw material for the detergent industry. The capability to analyze their fractional composition is important for quality control of these products. Capillary and packed-column gas chromatography (GC) was applied to determine the homolog distribution of directly ethoxylated 4-, 8-, and 14-mol methyl esters made from pure C_(12) fatty acid and technical-grade C_(12)-C_(18) fatty acids. Analytical procedures are described, and chromatograms are presented. Quantifications based on internal normalization are discussed. Quantifications based on internal normalization are discussed. Results demonstrate that both techniques are useful and give comparable results over the wide range of molecular weights investigated. Somewhat better separation is obtained with a capillary column, especially for the technical-grade products.