Ajh. Louter et al., ONLINE AUTOMATED SAMPLE PREPARATION - CAPILLARY GAS-CHROMATOGRAPHY FOR THE ANALYSIS OF PLASMA SAMPLES, Chromatographia, 40(9-10), 1995, pp. 500-506
An automated sample preparation module, (the automated sample preparat
ion with extraction columns, ASPEC), was interfaced with a capillary g
as chromatograph (GC) by means of an on-column interface. The system w
as optimised for the determination of the antidepressant trazodone in
plasma. The clean-up of untreated plasma was carried out with disposab
le C18 cartridges, using several washing steps. The analyte was desorb
ed with methanol, the extract was diluted on-line with buffer and prec
oncentrated on a PLRP-S trapping column. The trapping column was dried
by purging with nitrogen gas. Desorption (phase switching) of the tra
pping column was carried out with ethyl acetate which was introduced i
nto a retention gap using partially concurrent solvent evaporation con
ditions. Trazodone was determined by GC with flame ionisation detectio
n (FID). With a 1 ml sample, this resulted in a detection limit for tr
azodone in plasma of 3 ng/ml. The system showed good linearity and rep
eatability in the range 00.1-1 mu g/ml, thus covering the range of pha
rmacokinetic/dynamic-to-therapeutic concentrations of trazodone in pla
sma. Preliminary results for benzodiazepines are promising. They indic
ate that the use of a selective detector such as the nitrogen/phosphor
us detector, is to be recommended.