Oligomer-Specific, Short Chain Linear Alcohol Ethoxylate Quantification via Comprehensive Two-Dimensional Gas Chromatography

Abstract

Non-ionic linear alcohol ethoxylated surfactants (LAEs) make up a broadly utilized class of compounds commonly employed in unconventional hydraulic fracturing activities. However, current detection and quantification methods fail to operate in relevant concentration ranges and are limited in specificity because of a lack of access to all analytical standards for individual LAE oligomers. Here, we present a novel extraction and quantification technique for aqueous samples containing both petroleum hydrocarbons and short chain LAEs with alkyl chain lengths of 6–10 carbons and 0–9 ethylene oxide groups. Using liquid–liquid extraction and two-dimensional gas chromatography with flame ionization detection, the method provided over 80 and 100% recovery of LAEs and n-alkane hydrocarbons, respectively. Individual LAE oligomers were quantified using calibration curves of n-alkanes and adjusted response factors based on the effective carbon number (ECN) concept, and we present a detailed framework for calculating E...