茚三酮光度法测定室内空气中微量氨

目的建立测定室内空气中微量氨的新型光度分析法。方法用内装5mL0.01mol/LH2SO4溶液的气泡吸收管采集空气中的氨,在抗坏血酸存在和加热(95℃)条件下,于pH5.5～6.0的乙酸-乙酸钠缓冲介质中,氨与茚三酮反应生成蓝紫色化合物,于568nm比色定量。本法线性范围为0～8μg/10mL,日间精密度为2.8%～6.8%,加标回收率为96.2%～102.3%,方法检测限为0.06mg/m3。结论本法简便、快速、干扰少,用于实际室内空气样品中氨的测定,结果满意。

Determination of Trace Ammonia in Indoor Air by Ninhydrin Spectrophotometry

OBJECTIVE: To develop a new spectrophotometric method to detect trace ammonia in indoor air. METHODS: Ammonia in the air was absorbed by 0.01 mol/L sulfuric acid in a bubbling absorption tube. With 95 degrees C of water bath and pH 5.5-6.0 of buffer solution of acetic acid-sodium acetate, the ammonium in the solution reacted with ninhydrin at the presence of ascorbic acid to form a royal purple product which has a maximum absorbance at 568 nm. RESULTS: This method produced a linear range of 0-8 microg/10 mL. The detection limit was 0.06 mg/m3. The recoveries of the method ranged from 96.2% to 102.3%, with 2.8%-6.8% of relative standard deviations. CONCLUSION: The method is simple, rapid and safe. The common coexisting substances in the air do not interfere with the determination. The precision and accuracy can satisfy the requirements of the determination of trace ammonia in indoor air.