Determination of midazolam and its α‐hydroxy metabolite in plasma by gas chromatography with electron capture detection

Abstract

Abstract A sensitive GC‐ECD assay has been developed for the simultaneous determination of midazolam (I) and its α‐hydroxy metabolite (II) in plasma. The assay involves extraction of both compounds into ether at alkaline pH (pH 12), followed by silylation of the α‐hydroxy metabolite with N,O‐bis(trimethylsilyl) trifluoroacetamide (BSTFA). On extracting 0.5 ml of plasma, the sensitivity limits are 4ng/ml for I and 3ng/ml for II. If present, the minor urinary metabolites, the 4‐hydroxy (III) and the α,4‐dihydroxy compound (IV), can also be determined by this method.