[Study on the speciation of calcium in Baihu decoction]

A method for speciation analysis of calcium in Baihu decoction was presented. The six different forms of Ca in the filtrate including free ions, non-free ions, exchangeable, non-exchangeable, organic and inorganic were separated by using ion-exchange resin (IER), chelating resin and organic solvent extraction. Various forms of Ca were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The recovery for the method is 90.0%-110.0%. The result showed that baihu decoction extract was a kind of complex solution, in which 83.25% of Ca existed in free ions form and 23.79% of Ca existed in organic form in the soluble filtrate.