Screening of four beta‐blockers and codeine in urine by on‐line coupled RPLC‐GC with on‐line derivatization

Abstract

AbstractOn‐line coupled reversed phase liquid chromatography‐capillary gas chromatography (RPLC‐GC) was used in the separation of four derivatized beta‐blockers and codeine in urine. Sample clean‐up was accomplished in the LC part and compounds were separated in the GC part. After the LC column the aqueous phase was switched to organic solvent by on‐line liquid‐liquid extraction and the two phases were separated in a sandwich‐type phase separator. The organic extract was then transferred to a loop‐type LC‐GC interface. Beta‐blockers were derivatized on‐line in the interface before GC analysis. Concurrent eluent evaporation was used during the introduction of the sample fraction, and excess of solvent vapors was removed via an early vapor exit. The sample pretreatment was minimal; the only manual pretreatment step was the filtration of the urine sample.