On-line automated sample preparation-capillary gas chromatography for the analysis of plasma samples
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- Louter, A.J.H., van der Wagt, R.A.C.A. & Brinkman, U.A.T. Chromatographia (1995) 40: 500. doi:10.1007/BF02290259
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An automated sample preparation module, (the automated sample preparation with extraction columns, ASPEC), was interfaced with a capillary gas chromatograph (GC) by means of an on-column interface. The system was optimised for the determination of the antidepressant trazodone in plasma. The clean-up of untreated plasma was carried out with disposable C18 cartridges, using several washing steps. The analyte was desorbed with methanol, the extract was diluted on-line with buffer and preconcentrated on a PLRP-S trapping column. The trapping column was dried by purging with nitrogen gas. Desorption (phase switching) of the trapping column was carried out with ethyl acetate which was introduced into a retention gap using partially concurrent solvent evaporation conditions. Trazodone was determined by GC with flame ionisation detection (FID). With a 1 ml sample, this resulted in a detection limit for trazodone in plasma of 3 ng/ml. The system showed good linearity and repeatability in the range 0.01–1 μg/ml, thus covering the range of pharmacokinetic/dynamic-to-therapeutic concentrations of trazodone in plasma.
Preliminary results for benzodiazepines are promising. They indicate that the use of a selective detector such as the nitrogen/phosphorus detector, is to be recommended.