Author(s): Wei G, Xiao S, Liu C
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Abstract A rapid, sensitive and accurate liquid chromatographic-tandem mass spectrometric method is described for the determination of metolazone in human blood. Metolazone was extracted from blood using ethyl acetate and separated on a C18 column interfaced with a triple quadrupole tandem mass spectrometer. The mobile phase consisting of a mixture of acetonitrile, 10 mmol/l ammonium acetate and formic acid (60:40:0.1, v/v/v) was delivered at a flow rate of 0.5 ml/min. Electrospray ionization (ESI) source was operated in positive ion mode. Selected reaction monitoring (SRM) mode using the transitions of m/z 366-->m/z 259 and m/z 321-->m/z 275 were used to quantify metolazone and the lorazepam (internal standard), respectively. The linearity was obtained over the concentration range of 0.5-500 ng/ml for metolazone and the lower limit of quantitation (LLOQ) was 0.5 ng/ml. For each level of QC samples, inter- and intra-run precision was less than 8.07 and 3.56\% (relative standard deviation (RSD)), respectively, and the bias was within +/-4.0\%. This method was successfully applied to the pharmacokinetic study of metolazone formulation after oral administration to humans.
This article was published in J Chromatogr B Analyt Technol Biomed Life Sci
and referenced in Journal of Bioanalysis & Biomedicine