M. Gergov et al., Simultaneous screening and quantitation of 18 antihistamine drugs in bloodby liquid chromatography ionspray tandem mass spectrometry, FOREN SCI I, 121(1-2), 2001, pp. 108-115
A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method is prese
nted for the simultaneous screening and quantitation of 18 antihistamine dr
ugs in blood samples. Sample pretreatment involved liquid-liquid extraction
of the basic antihistamines followed by a second extraction of the acidic
antihistamines. The recoveries were 43-113% for basic drugs and 23-66% for
acidic drugs. The combined extracts were run by LC on C-18 reversed phase c
olumn using acetonitrile-ammonium acetate mobile phase at pH 3.2. The mass
spectrometric analysis was performed with a triple stage quadrupole mass an
alyzer. Screening was performed using Multiple reaction monitoring (MRM) an
d any compounds tentatively identified as, antihistamine drugs were then au
tomatedly verified by their Product Ion Spectra in a subsequent MS/MS run.
Quantitation was based on the MRM data from the screening step. In validati
on tests, the method showed good linearity at the relevant concentrations.
The attained limits of quantitation varied between 0.0005 and 0.01 mg/l in
blood and were lower than the therapeutic concentrations (C-max). The limit
s for identification by Product Ion Spectra were also lower than C-max, exc
ept for clemastine, which has exceptionally low concentrations in blood. Th
e intra-assay relative standard deviations were better than 10% and the ina
ccuracy varied between 39% for levocabastine and 5% for cyclizine, the majo
rity of the values being <20%. (C) 2001 Elsevier Science Ireland Ltd. All r
ights reserved.