示波极谱法测定空气中的痕量氨

Determination of Trace Ammonia in Air by Oscilloscopic Polarography

作者对空气中氨的采样方法进行了研究,并建立了用次溴酸钠将氨氧化成亚硝酸盐后,经磺胺和盐酸萘乙二胺偶联,再在碱性介质中进行极谱测定的方法。其线性范围为0～3.0μg/10ml,方法灵敏度较常规的纳氏比色法高50倍,检出限为3.6μg/ml,变异系数为2.0～9.5％,回收率为93.0～108.7％。本法简便、快速,测定条件易于控制、重现性、稳定性均好,适合于空气中痕量氨的测定。

Air sample was collected in 10ml of 5mmol/L sulfuric acid (flow rate 0.3L min^(-1)) using a fritted bubbler. Then the ammonium salt in absorbing solution was oxidized quantitatively by sodium hypobromite to nitrite which can form an azo complex with sulphanilamide and N-1-naphthyl-ethylenediamine hydrochloride. The azo complex in alkaline solution was determined by oscilloscopic polarography at approximately-0.64 V (vs. SCE). The peak height was proportional to the concentration of ammonia in range of 0-3.0μg/10ml. The method's sensitivity was 50 times higher than that of Nessler's method. The detection limit was 3.6ng/ml, the average recovery 101.9％. ranging from 93.0％-108.7％, coefficient of variation 2.0-9.5％. This method was simple, quick, reliable and was suitable for analyzing trace ammonia in air.