title: At-line solid-phase extraction for capillary electrophoresis: application to negatively charged solutes.
abstract: The analysis of complex biological samples with capillary electrophoresis (CE) requires proper sample pretreatment. In this paper the applicability of solid-phase extraction (SPE) coupled at-line with CE is studied, by using a laboratory-made interface. A fresh (disposable) SPE cartridge is used for each sample to prevent carry-over effects. The sample handling procedure is performed parallel with the analysis of the previous sample, to improve sample throughput. Using this set-up, negatively charged test compounds (some non-steroid anti-inflammatory drugs) can be determined in serum and urine. The method is linear over at least two decades and detection limits are around 40 microg/l. A single capillary, flushed only once a week with a sodium hydroxide solution, was used without problems for the analysis of ca. 900 samples during 1 year. The robustness of the system was very good: no blocking of loop, interface or capillary was found during this period. Furthermore, the system was successfully used for overnight runs.
authors.affiliation: Vrije Universiteit, Department of General and Analytical Chemistry, Amsterdam, The Netherlands.
authors.forename: J R
authors.initials: JR
authors.lastname: Veraart
authors.forename: C
authors.initials: C
authors.lastname: Gooijer
authors.forename: H
authors.initials: H
authors.lastname: Lingeman
authors.forename: N H
authors.initials: NH
authors.lastname: Velthorst
authors.forename: U A
authors.initials: UA
authors.lastname: Brinkman
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000032:analysis* / Q000097:blood / Q000652:urine; D002138:Calibration; D004563:Electrochemistry; D019075:Electrophoresis, Capillary / Q000379:methods*; D006801:Humans; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal