Report on the preparation of deuterium-labelled aconitine and mesaconitine and their application to the analysis of these alkaloids from body fluids as internal standard.

Improved analysis of aconitine and mesaconitine, highly toxic compounds from Aconitum species, in body fluids by gas chromatography-selected ion monitoring with their deuterium-labelled analogues as internal standards (I.S.s) is described. Deuterium-labelled analogues of aconitine and mesaconitine were synthesized by the substitution of the N-alkyl group for a deuterium-labelled one. The mass spectra of the derivatives of the deuterium labels closely resembled that of the nonlabelled compounds except for an obvious mass shift produced by substitution of the deuterium atoms at N-alkyl groups. Using these deuterium-labelled compounds as I.S.s, the standard curves for aconitine and mesaconitine were linear (r2=0.999 each) in the concentration range of 50 pg to 50 ng, respectively. The detection limit of the alkaloids was 10 pg each per injection. The recovery, accuracy and precision of the analysis were evaluated with three different concentration of spiked human blood and urine (n=5 each). The recovery rates ranged from 97.6% to 101.3% and the standard deviations of the interseries ranged from 2.1% to 3.9%. These I.S.s give us a more precise analysis and may be useful in examining the behavior of these alkaloids in the human body.