The HPLC analytical method was established for quantifing the diester-alkaloids content in the decoctions before and after Radix aconiti combined with Rhizoma pinelliae, Rhizoma pinelliae praeparatum, Fructus trichosanthis, Pericarpium trichosanthis, Semen trichosanthis, Bulbus fritillariae thunbergli, Bulbus fritillariae cirrhosae, Radix ampelopsis and Rhizoma bletillae, respectively. The components and content of alkaloids in these decoctions was also investigated by semi-quantitative ESI-MS. For the co-decoctions of Radix aconiti combined with Rhizoma pinelliae, Semen trichosanthis, Fructus trichosanthis, Pericarpium trichosanthis, Bulbus fritillariae thunbergli and Rhizoma bletillae, respectively, the content of diester-alkaloids is more than that of single Radix aconiti decoction. For the decotions of Radix aconiti combined with Rhizoma pinelliae praeparatum, Bulbus fritillariae cirrhosae and Radix ampelopsis, respectively, content of the diester-alkaloids is similar or much less than single Radix aconiti decoction. The semi-quantitative ESI-MS method gained accordant result with HPLC analytical method, and the analytical results of the diester-alkaloid content were also similar with the LD50 results of these Chinese herb-pairs. Additionally, it is found that the content of diester-alkaloids in decoctions was correlated with the decoction pH.

Key words: Radix aconiti, eighteen incompatible medicaments, combination, HPLC