EDTA减量滴定法快速测定固体饮料中微量铜

Rapid determination of trace copper in powdered drinks by EDTA titrimetry

采用EDTA减量滴定法测定固体饮料中的微量铜。样品用HNO3-HClO4湿消化后,先在pH=5￣6时,以二甲酚橙为指示剂,用EDTA标准溶液测定金属离子的总量;然后在另一份试样中,用硫脲掩蔽铜,再用EDTA标准溶液测定铜以外的其它金属离子。两者之差即相当于铜的量。测定结果的相对标准偏差RSD0.48%,回收率(R)在98.2%￣100.6%之间。

Trace copper in powdered drinks is determined by the EDTA titrimetry. First, the samples are wetly digested by HNO3- HCIO,. Then, in one wetly digested sample, with XO as the indicator, the total amount of metallic ions is determined with the standard solution of EDTA while the pH is 5 - 6. And in another wetly digested sample, thiourea is added to mask Cu^2＋, then metallic ions other than Cu^2＋ are determined with the standard solution of EDTA. The difference between the two results is the amount of copper. The RSD% is 0.48% and R is between 98.8% and 100.6%.