电位溶出法间接测定血清中钙镁

INDIRECT DETERMINATION OF CALCIUM AND MAGNESIUM IN SERUM BY POTENTIOMETRIC STRIPPING ANALYSIS

利用钙置换Zn EGTA中锌 ,镁置换Zn EDTA中锌 ,采用计时电位溶出法间接地测定血清中钙镁含量。血清用量仅为 2 0 μl,且不必消化 ,钙的线性范围为 0～ 4 80 μg·L- 1,检出限为 2 μg·L- 1,相关系数为 0 .9976 (n =6 ) ,镁的线性范围为 0～ 2 88μg·L- 1,检出限为 1μg·L- 1,相关系数为0 .9984 (n =6 )。用模拟血清测定钙的平均回收率为 99.4 % ,镁的平均回收率为 10 0 .1%。

The chrono-potentiometric stripping analysis was applied to the indirect determination of calcium and magnesium in blood serum. Replacement reactions between Ca 2+ ion and Zn-EGTA complex and between Mg 2+ ion and Zn-EDTA complex were utilized and the determinations were carried out in ammoniacal buffer solutions of pH 9.26 for calcium and of pH 9.86 for magnesium, respectively. The measurements were carried out under the following experimental conditions electrolysis voltage--1.3V, concentration time-1min 20 stripping time-20s. Linearity for determination of calcium was found to be in the range 0～480μg per liter, with a cor relation coefficient of 0.9976 (n=6); and for determination of magnesium in the range 0～288μg per liter with a correlation coefficient of 0.9984 (n=6). A detection limit of 2μg·L -1 was found for both calcium and magnesium determination. An average recovery of 99.4% was found for calcium and of 100.1% for magnesium by the analysis of some simulated serum samples. Only 20μl of serum sample were required by this analysis and it was not necessary to digest the sample with nitric acid.