摘要
在pH11．0的氨水-氯化铵介质中，苦胺酸偶氮变色酸与钙离子生成稳定的络合物，导致显色剂褪色，据此建立了褪色光度法测定药物中的钙含量。对反应介质的酸度及缓冲溶液的用量、显色剂的用量、反应时间和共存离子的干扰等影响因素进行了试验并予以优化。在590nm波长处测定时，钙的质量浓度在0．32～3．60mg·L^-1范围内，反应体系吸光度的降低值△A与钙离子浓度呈线性关系，表观摩尔吸光率为1.26×10^4L·mol^-1·cm^-1。用该方法测定药物中钙的含量，其结果与EDTA法相符，测定值的相对标准偏差（n=10）在1．5％～2．1％之间。
A stable complex was formed by the reaction of Ca^2＋ with the color reagent, picramine CA in an ammoniacal buffer medium of pH 11. Influential/actors, including the pH and amount of buffer solution, amount of color reagent, time of reaction, and interferences of co-existing ions were studied and optimized. Linear relationship between the magnitude of decrease in absorbance of the color reagent and the mass concentration of Ca^2＋ was obtained in the range of 0. 32-3.60 mg ·L^-1 , and value of apparent molar absorptivity found was 1.26×10^4L·mol^-1·cm^-1 when measured at the wavelength of 590 nm. The proposed method was used in the determination of Ca^2＋ in drugs, the results obtained were checked quite well with those found by EDTA titrimetry, and values of RSD＇s （n=10） found were in the range of 1.5%-2. 1%.
出处
《理化检验（化学分册）》
CAS
CSCD
北大核心
2009年第7期818-819,824,共3页
Physical Testing and Chemical Analysis(Part B:Chemical Analysis)
