Determination of aconitine in body fluids by LC-MS-MS

A very sensitive and specific method was developed for the determination of aconitine, the main toxic alkaloid from plants of the genus Aconitum L., in biological samples. The method comprised solid-phase extraction using mixed-mode C₈ cation exchange columns followed by liquid chromatography-tandem mass spectrometry (LC-MS-MS). Chromatographic separation was achieved with a RP₈ column. Detection of aconitine was achieved using electrospray in the positive ionisation mode and quantification was performed using multiple reaction monitoring with m/z 646.4 as precursor ion, i.e. [M+H]⁺ of aconitine and m/z 586.5, m/z 526.4 and m/z 368.4 as product ions after collision-induced dissociation. The method was fully validated for the analysis of blood samples: the limit of detection and the limit of quantitation were 0.1 ng/g and 0.5 ng/g, respectively. Within the linear calibration range of 0.5–25 ng/g, analytical recovery was 79.9%. In two fatal cases with suspected aconite intoxication, aconitine could be detected in blood samples at concentrations of 10.0 and 12.1 ng/g. In one case, aconitine could also be detected in the stomach content (3 ng/g) and in the other in the urine (180 ng/ml).