硝酸钾-硫氰酸铵-水体系萃取浮选硫氰酸亚铜间接测定头孢拉定

Indirect Determination of Cefradine by Extraction Flotation CuSCN in Potassium Nitrate-Ammonium Thiocyanate-Water System

建立了硝酸钾．硫氰酸铵．水体系萃取浮选铜间接测定头孢拉定的新方法。结果表明，在SCN^-、KNO，存在下及控制溶液pH值为4．0～6．0，头孢拉定完全降解为巯基（-SH）化合物，且巯基（-SH）能使Cu（Ⅱ）还原为Cu（Ⅰ），所生成的Cu（Ⅰ）与SCN^-形成CuSCN白色乳状沉淀而浮选至水相表面，根据溶液中剩余Cu（Ⅱ）的量可间接测定头孢拉定的含量。CuSCN的浮选率E（％）与头孢拉定的含量之间存在良好的线性关系。当Cu（Ⅱ）加入量为50μg时，线性范围为0．3～12．0mg／L。检出限为0．25mg／L。方法用于胶囊、血清、尿样中头孢拉定含量的测定，结果令人满意。

A novel method for indirect determination of cefradine by extraction flotation of CuCSN with potassium nitrate-ammonium thiocyanate-woter system was developed. At pH 4. 0 to 6. 0, in the existence of SCN^-, the thiol group（-SH） of the degradation product of cefradine could reduce Cu（ Ⅱ ） to Cu（ Ⅰ ）, and the resulting Cu（ Ⅰ ） could react with SCN^- to form white emulsion precipitate CuSCN. In the presence of KNO3 , this precipitate ascended and floated on the surface of water. The amount of cefradine can be determined by, measuring the flotation yield of Cu（ Ⅱ ）. When the amount of added Cu（ Ⅱ ） is 50 μg, the linear range is maintained in the range 0. 3 - 12.0 mg/L with a correlation coefficient of 0. 999 2. The detection limit is 0. 25 mg/L. This proposed method was successfully applied to the determination of cefradine in capsules and the recovery of cefradine in urine and human plasma with satisfactory results.