微波消化-分光光度法测定牛奶中钙含量

建立了微波消化-分光光度法测定牛奶中钙含量的方法,研究了缓冲溶液种类、物质的量浓度、pH值、邻甲酚酞和三乙醇胺用量、显色时间等对测定结果的影响,对测定条件进行了优化.在pH=11.0的氨性缓冲溶液中,钙与邻甲酚酞迅速形成紫色络合物.该法用于测定市售牛奶样品得到较满意的结果,Ca2＋质量浓度在0.02～2.50μg/mL范围具有良好的线性关系（R2=0.999 9）,回收率在84%～108%之间.

Determination of Calcium in Mil by Microwave Digested-Spectrophotometry

A method was developed for the determination of o-cresol phthalate calcium in milk by microwave digestion-spectrophotometry.The effect of the buffer type,concentration,pH,amount of o-cresolphthalein and triethanolamine and color time were investigated,and that the determining condition was optimized in this study.The results showed that in the pH=11.0 ammonia buffer solution,calcium and o-cresolphthalein formed the purple complex rapidly.The method was used to determine the commercial milk samples with satisfactory results.The calibration curve had good linear in the ranges of 0.02～2.50 μg/mL（R2= 0.999 9）for calcium concentration.The recovery rate was about 84.4%～108%.