Mixed surfactant systems based on primary amine and medium-chain fatty acid: Micelle-mediated microextraction of pesticides followed by the GC–MS determination

Abstract

Mixed surfactant systems based on primary amine and medium-chain fatty acid were investigated and used for the micelle-mediated microextraction for the first time. It was established, that injection of the mixture of primary amine and medium-chain fatty acid into an aqueous sample phase led to formation of a micellar solution. The obtained micellar solution can be used for analytes separation from solid food samples. The addition of salting-out agent into the micellar solution promoted formation of non-viscous surfactant-rich phase and extraction of analytes. The surfactant-rich phase obtained after centrifugation was found to be compatible with a gas chromatography–mass spectrometry (GC–MS) system without any dilution to reduce phase viscosity. Various primary amines and medium-chain fatty acids were studied for the micelle-mediated microextraction from sample suspension and the system based on 1-nonylamine and pivalic acid (3: 2, v/v) was evaluated as the most effective. The surfactant-rich and aqueous phases were investigated in detail to reveal the mechanism of the proposed microextraction procedure. A novel micelle-mediated microextraction for the determination of pesticides (diazinon, triadimefon, triadimenol and bifenthrin) in food samples by GC–MS was developed. The limits of detection, calculated from blank test, were established to be 8 μg kg−1 for diazinon, 10 μg kg−1 for triadimefon, 5 μg kg−1 for triadimenol, and 1 μg kg−1 for bifenthrin. The microextraction procedure can be characterized as fast (7 min), simple and cheap.