Analysis of toxic norditerpenoid alkaloids in Delphinium species by electrospray, atmospheric pressure chemical ionization, and sequential tandem mass spectrometry

A rapid electrospray mass spectrometry method was developed for screening l arkspur (Delphinium spp.) plant material for toxic norditerpenoid alkaloids . The method was calibrated using two standard alkaloids, methyllycaconitin e (1) and deltaline (2), with a recovery of 92% from spiked samples and rel ative standard deviations of 6.0% and 8.1% for the two alkaloids, respectiv ely. Thirty-three samples of plains larkspur, Delphinium geyeri, were analy zed. Methyllycaconitine (1) concentration was 0.27% +/- 0.08% during a 1-mo nth period in 1997 establishing the relative risk of poisoning from the pla nt to be low. The method was also applied to the trace analysis (<1 ppm) of 1 in serum samples from sheep dosed different levels of the alkaloid. Elec trospray ionization combined with sequential tandem mass spectrometry and H PLC coupled to atmospheric pressure chemical ionization (APCI) mass spectro metry were used to detect and tentatively identify three new norditerpenoid alkaloids from Delphinium nuttallianum [bearline (6), 14-acetylbearline (7 ), 16-deacetylgeyerline (8)]. The tentative structure of the new alkaloids was predicted from the tandem mass spectra fragmentation patterns and assig ning the substitution pattern for methoxy and acetyl groups at the C-14 and C-16 carbons.