【摘要】 <正> dE/dt—E曲线因有独特优点被广泛应用于滴定分析。使用汞膜电极,在pH6左右的醋酸—醋酸钠缓冲液中,或在pH9～10的硼砂—氢氧化钠—醋酸钠缓冲液中,EDTA的dE/dt—E曲线上有明显的切口,可用于滴定非示波极谱活性的金属离子。但在0.01M NaOH底液中,EDTA的切口不明显(见图1),而且位置靠近左侧亮点,这种切口不灵敏,不能用于滴定分析。但在同样的电极和底液条件下,采用dE/dt—t曲线却可得到良好结果。Heyrovsky曾采用高压高阻线路,使去极剂在dE/dt—t产生折扭。采用本文的低压低阻线路,并控制一定的交、直流电压,去极剂在dE/dt—t曲线上能产生切口。凭籍切口的出现或消失指示滴定终点。采用此法指示终点应用于EDTRA滴定葡萄糖酸钙,其测定结果与中国药典法一致,且由于终点指示不受不溶物更多还原

【Abstract】 In the buffers of HOAc-NaOAc （pH 6）or Na₂B₄O₇-NaOH-NaOAc（pH 9—10）,EDTA gives an incision on dE/dt-E curve, which can be used to determine the end-point of titration of oscillopolarographically inactive metal ions,when mercury film electrode is used. In 0.01M NaOH solution,the incision on dE/dt-E curve due to EDTA is ambiguous and can not be used in titration,but the incision on the dE/dt-t curve is very sharp and sensitive and can be used to indicate the end-point of EDTA titration of calcium gluconate. In NH₄OHNH₄C1 buffer solution, both anodic and cathodic incisions of Zn⁺⁺ on dE/dt-t curve are sensitive and sharp. Therefore dE/dt-t curve is sometimes better than dE/dt-E curve.更多还原