Objective: The Ca2+ content in calcium standard solution

the gypsum decoction

Baihu decoction

Maxing Shigan decoction and Zhuye Shigao decoction was determined by comparing the difference of EDTA titration method and ICP-OES method to discuss the effect of organic matric and other factors of decoction with the degree of Ca2+ content on using EDTA titration and to establish a credible method of Ca2+leaching quantity of the decoction. Method: The EDTA titration method and the ICP-OES method results were compared to determine Ca2+ content of the same sample in calcium standard solution

gypsum decoction

Baihu decoction

Maxing Shigan decoction and Zhuye Shigao decoction. Result: The results of the calcium standard solution between EDTA titration method and ICP-OES determination were no significant(P>0.05)

two methods were the same results.The results of Ca2+ content were significantly different with the determination of two methods for gypsum

Baihu decoction

Maxing Shigan decoction and Zhuye Shigao decoction(P<0.01).The value of results by EDTA direct titration method was higher than that by ICP-OES method. Conclusion: Ca2+content determination by using EDTA titration is affected with the complex degree of sample's organic matrices

influence factors on the determination of EDTA titration methods are homogeneous and linear relationship.The Ca2+ content determination result value of decoction is high by EDTA direct titration method

and it is less suitable for the determination of Ca2+ content of the traditional medical formulae.