Assessment of a dynamic hollow-fibre liquid phase microextraction system for human blood plasma samples

A dynamic liquid phase microextraction (LPME) system, based on hollow-fibre supported liquid membrane (SLM) extraction, was developed for extracting ionisable xenobiotics from human plasma, and its performance was evaluated (in terms of extraction efficiency, reproducibility, durability and carry-over) using nitrophenolic compounds as model analytes at concentrations of 0.1-0.5 microg mL(-1) in aqueous standards. The efficiency and repeatability were tested also on spiked human plasma. The system is non-expensive, convenient, requires minimal manual handling and enables samples with volumes as small as 0.2 mL to be extracted. For plasma samples extraction efficiencies of between 30 and 58% were achieved within 20 min, including washing steps. The limit of detection (LOD) values were in the range 0.02-0.03 microg mL(-1). The developed system can provide enrichment factors up to eight, based on the injection-to-acceptor volume ratio (in this case 0.2-0.025 mL). The same hollow-fibre membrane was used up to 8 days with no loss of efficiency. Carry-over was lower than detection limit.