Hollow fiber membrane-coated functionalized polymeric ionic liquid capsules for direct analysis of estrogens in milk samples

Protein removal process is always time-consuming for the analysis of milk samples. In this work, hollow fiber membrane-coated functionalized polymeric ionic liquid (HF-PIL) capsules were synthesized and used as solid-phase microextraction (SPME) sorbent for direct analysis of estrogens in milk samples. The functionalized PIL monolith sorbent was obtained by copolymerization between 1-(3-aminopropyl)-3-(4-vinylbenzyl)imidazolium 4-styrenesulfonate IL monomer and 1,6-di(3-vinylimidazolium) hexane bishexafluorophosphate IL-crosslinking agent. A group of four capsules were installed as SPME device, to determine four kinds of estrogens (estrone, diethylstilbestrol, hexestrol, and 17 alpha-ethynylestradiol) in milk samples, coupled to high performance liquid chromatography. Extraction and desorption conditions were optimized to get satisfactory extraction efficiency. Good linearity was obtained in the range of 5-200 mu g L-1. The limits of detection were 1 mu g L-1 for diethylstilbestrol and 2 mu g L-1 for 17 alpha-ethynylestradiol, estrone, and hexestrol. The present method was applied to analyze the model analytes in different milk samples. Relative recoveries were in the range of 85.5-112 %. The HF-PIL SPME capsules showed satisfactory extraction efficiency and high resistance to sample matrix interference.