调节pH抑制亚硝酸盐对碘量法测定溶解氧干扰的抑制作用

Interference suppression of nitrite in the determination of dissolved oxygen with iodimetry by adjusting pH

为进一步提高碘量法测定溶解氧(DO)对亚硝酸盐存在的上限,提出在滴定前调节溶液pH在4～5,以抑制亚硝酸盐的干扰。实验表明此法适用于亚硝酸盐质量浓度在5～300 mg/L的水样溶解氧测定,在较高浓度亚硝酸盐存在的条件下,此法对DO质量浓度在2～10 mg/L的水样均具有较高的准确度。

To measure the dissolved oxygen （DO） in water containing higher concentration nitrite, the iodimetry is modified by adjusting the pH value around 4 -5 before titration to suppress the interference of nitrite. The results show that, the modified iodimetry method is suitable for measuring DO in water containing nitrite around 5 - 300 mg/L. When the concentration of nitrite is relatively high, this method still can determinate the water samples with concentration of DO around 2 - 10 mg/L accurately.