Simultaneous determination of atracurium and its metabolite laudanosine in post-mortem fluids by liquid chromatography/multiple-stage mass spectrometry on an ion trap

A method was developed to accurately quantify atracurium (a non-depolarizing skeletal muscle relaxant) and its metabolite laudanosine in post-mortem specimens. Analytes were isolated from blood and tissues by liquid/liquid extraction after adding vecuronium as an internal standard. Chromatographic separation was accomplished by gradient elution in a Synergy Max RP 150 x 2.1 mm column. Positive ion electrospray ionization and mass spectrometric analyses were carried out in an ion trap mass spectrometer under collision-induced dissociation conditions. The method proved selective and sensitive, and was validated in post-mortem blood, heart, lung and liver in the range of 1-2000 ng/mL (blood) and 5-5000 ng/g (tissues); the limits of quantification obtained were 1 ng/mL in blood and 5 ng/g in tissues.