Analysis of rocuronium in human whole blood and tissues using liquid chromatography-tandem mass spectrometry

A rapid, accurate and sensitive liquid chromatography-tandem mass spectrometry method has been developed for the determination of a quaternary nitrogen muscle relaxant, rocuronium, in human blood. The procedure involves protein precipitation with chloroform and trichloroacetic acid, and purification using methanol. The chromatography was performed using a phenyl-hexyl column (150 × 2.0 mm i.d., 3 μm; Phenomenex) with a mobile phase consisting of 5 mM ammonium formate (pH 3.0) and acetonitrile. Multiple reaction monitoring was used for quantification. The assay was linear over a concentration range of 4-500 ng/mL for rocuronium with R² ≥ 0.998. The recoveries for this compound ranged from 96.0 to 109.1%. The intra-day and inter-day precision was less than 10.5% and the accuracy ranged from 106.6 to 114.9%. The validated method was applied to quantify the content of rocuronium in blood and a variety of tissues of a victim suspected of overdose. In conclusion, the method was successfully applied for the analysis of rocuronium in biological samples for forensic toxicology.