EDTA滴定法测定芎芷石膏汤中钙离子含量

Content determination of calcium in Xiongzhishigao decoction by EDTA titration

目的建立乙二胺四乙酸二钠(EDTA)络合滴定法测定芎芷石膏汤中钙离子含量。方法芎芷石膏汤样品经无水乙醇脱色处理后,单因素结合正交试验对影响钙离子滴定反应的钙离子浓度、滴定pH值、稀盐酸加入量、指示剂加入量、掩蔽剂5个因素进行考察。以钙标准溶液EDTA用量对其浓度作线性回归,并对测定方法进行精密度、稳定性、重复性、加样回收率试验。在优化条件下测定3批芎芷石膏汤样品中钙离子含量。结果确定最佳测定条件为取样0.1 g,滴定pH值为13,稀盐酸加入量为2.0 ml,指示剂加入量为0.15 g,不加掩蔽剂。该测定方法下,钙离子浓度在0.60~2.98 mmol/L范围内呈现良好的线性关系,回归方程为y=10.05x-0.0498,r=0.9999。精密度、稳定性、重复性试验均RSD<3%,平均加样回收率为100.54%,RSD为0.72%(n=6)。以上均符合定量分析要求。3批芎芷石膏汤样品中钙离子含量分别为40.29,41.22,39.90 mg/g。结论优选的EDTA络合滴定法操作简便、准确可靠,可用于芎芷石膏汤中钙离子含量的测定。

Objective To establish an ethylenediamine tetraacetic acid(EDTA)complexometric titration method for determining calcium content in Xiongzhishigao decoction.Methods After the sample of Xiongzhishigao decoction was decolorized by anhydrous ethanol,five factors affecting the calcium titration reaction,including calcium concentration,pH value of titration,dilute hydrochloric acid amount addition,indicator amount addition and masking agent,were investigated by single factor combined with orthogonal test.The linear regression between EDTA consumption of calcium standard solution and its concentration was analyzed.The precision,stability,repeatability and recovery rate tests were carried out.The calcium content in three batches of Xiongzhishigao decoction was determined under the optimized conditions.Results The optimum conditions were as follows:sampling 0.1 g,pH value of 13,dilute hydrochloric acid addition 2.0 ml,indicator addition 0.15 g and no masking agent.Under this method,there was a good linear relationship in the range of 0.60-2.98 mmol/L,and the regression equation was y=10.05 x-0.0498,r=0.9999.The RSDs of precision,stability and repeatability tests were all lower than 3%.The average recovery rate was 100.54%and RSD was 0.72%(n=6).All met the requirements of quantitative analysis.The calcium content in three batches of Xiongzhishigao decoction was 40.29,41.22,39.90 mg/g under the optimum conditions,respectively.Conclusion The optimized EDTA complexometric titration method is simple,accurate and reliable,and can be used for calcium content determination in Xiongzhishigao decoction.