title: Two-step liquid-liquid-liquid microextraction of nonsteroidal antiinflammatory drugs in wastewater.
abstract: A simple and novel two-step liquid-liquid-liquid microextraction technique combined with reversed-phase HPLC has been developed for the determination of the nonsteroidal antiinflammatory drugs ibuprofen and 2-(4-chlorophenoxy)-2-methylpropionic acid in wastewater samples. In the first step, the analytes were extracted from an acidified sample (donor solution) into 1-octanol immobilized in the pores of 10 pieces of polypropylene hollow fiber and further into a basic acceptor phase inside the hollow fiber channels. This first extraction step, using 0.01 M NaOH as the acceptor phase and 0.1 M HCl within the donor phase, had a 100% relative recovery with an enrichment factor of 100-fold. The extract in the first step was then adjusted to acidic condition with HCl. It now represented the donor phase for the second step of the extraction, using a single piece of hollow fiber, with 2 microL of 0.01 M NaOH solution as the acceptor phase. This analyte-enriched acceptor phase was subsequently withdrawn into a microsyringe and directly injected into an HPLC system for analysis. With this two-step microextraction, sensitivity enhancement of >15,000-fold could be obtained. Detection limits of < or =100 ng/L could be achieved for both compounds. The method was applied to the analysis of wastewater.
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Republic of Singapore 117543.
authors.forename: Xiujuan
authors.initials: X
authors.lastname: Wen
authors.forename: Chuanhong
authors.initials: C
authors.lastname: Tu
authors.forename: Hian Kee
authors.initials: HK
authors.lastname: Lee
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid; D002995:Clofibric Acid / Q000302:isolation & purification; D004785:Environmental Pollutants / Q000302:isolation & purification*; D007052:Ibuprofen / Q000302:isolation & purification; D013056:Spectrophotometry, Ultraviolet; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D004785:Environmental Pollutants; D014874:Water Pollutants, Chemical; D002995:Clofibric Acid; D007052:Ibuprofen