Evaluation of an on-line coupled continuous flow liquid membrane extraction and precolumn system as trace enrichment technique by liquid chromatographic determination of bisphenol A.

An on-line coupled continuous flow liquid membrane extraction (CFLME) and C(18) precolumn system was developed for sample preconcentration in liquid chromatography determination. After preconcentration by CFLME, which is based on the combination of continuous flow liquid-liquid extraction and supported liquid membrane, bisphenol A (BPA) was enriched in 960 microl of 1 mol l(-1) NaOH used as acceptor. This acceptor was on-line neutralized and transported onto the C(18) precolumn where analytes were absorbed and focused. Then the focused analytes were injected onto a C(18) analytical column for separation and detected at 220 nm with a diode array detector. CFLME related parameters such as flow rates, pH of donor and acceptor, and enrichment time were optimized. The proposed method presents a detection limit of 0.03 microg l(-1) (S/N=3) when 60 ml samples was enriched with an enrichment time of 30 min. Compared with C(18) based column-switching procedure, this proposed procedure presents similar sample throughput and lower detection limits. The proposed method was successfully applied to determine BPA in tap water, river water, and municipal sewage effluent samples.