分光光度法测定铋系超导材料中钙

Determination of Calcium in Bismuth Based Superconductor by Spectrophotometry

在pH=10.6的NH3-NH4Cl缓冲溶液中,钙离子和酸性铬蓝K显色,于498nm波长处以试剂空白作参比,测定该显色液的吸光度。建立了铋系超导前驱粉(Bi2Sr2Ca2Cu3Ox)中直接测定钙含量的方法。试样中大量存在的锶不干扰测定,用柠檬酸溶液作掩蔽剂,消除了铜的干扰。ε=9.0×103L·mol-1·cm-1,Ca在0—50μg·25mL-1范围内吸光度和浓度有良好的线性关系,回归系数r=0.9994。对合成样品进行6次测定,相对误差为-0.93%。对两种实际样品分别进行6次测定,RSD分别为1.63%和1.19%。

Calcium in superconductor was determined by spectrophotometry based on the complex of Ca and ACBK with the absorbance at 498nm and ε=9.0×10^3L·mol^-1·cm^-1 in pH 10. 6 NH3-NH4Cl buffer medium. The interference of Cu can be sheltered by citric acid. The coexisting Sr,Bi,Pb and other ions had no influence. A good linear relationship was obtained in the range of 0-50μg Ca · 25mL^-1 with r=0. 9994.