连续流动分析-水杨酸盐分光光度法测定空气中的氨

Determination of ammonia in air by continuous flow analysis-salicylate spectrophotometric method

目的建立并优化空气中氨的连续流动分析-水杨酸盐分光光度法。方法用装有10 ml 0.005 mol/L稀硫酸溶液的大型气泡吸收管,采集5 L模拟空气样品,溶液中的氨在碱性条件(p H=12)及亚硝基铁氰化钠存在下,与水杨酸盐和次氯酸钠反应生成蓝色化合物,采用连续流动分析仪,于波长660 nm处测定吸光度,比色定量;分析标准曲线、检出限、精密度、准确度,同时优化试剂、p H值。结果样品测定结果为0.054 mg/m^3~4.12 mg/m^3,本法标准曲线线性范围为0.01 mg/L^5.00 mg/L,相关系数(r)为0.999 9;以采集5 L空气计算,方法最低检出浓度为0.01 mg/m^3;相对标准差为0.95%~3.70%;加标回收率为98.0%~104.0%,测量国家有证标准物质,结果在定值范围内。结论本法检出限低、线性范围宽、重现性好、准确度高,操作简单自动化,分析周期短,在大批量样品测定中有明显优势。

Objective To establish and optimize the method for detemiantion of ammonia in air by continuous flow analysis-salicylate spectrophotometry.Methods To collecte 5 L air sample with large bubble absorption tubes containing 10 ml 0.005 mol/L dilute sulfuric acid solution; at the alkaline condition（ p H = 12） and in the presence of sodium nitoprussidethe,ammonia in the solution formed a blue compound with alicylate and sodium hypochlorite reaction,and then the production was tested by continuous flow analysis and colorimetric quantification was made by the determination of absorbance at wavelength of 660 nm;meanwhile,the standard curve,the detection limit,the precision and the accuracy were analyzed,and the reagents and p H value were optimized as well.Results The detection results were within 0.054 mg/m^3-4.12 mg/m^3,the linear range of the method was within 0.01 mg/L-5.00 mg/L,and the correlation coefficient（ r） was 0.999 9.The lowest detection concentration of this method was 0.01 mg/m^3（ 5 L air sample）.The relative standard deviations（ RSDs） were within 0.95%-3.70%,and the recovery rates were within 98.0%-104.0%.The certified reference material was detected and the results were within the range of given value.Conclusion The method is of low detection limit,wide linear range,good repeatability,high accuracy,simple operation,short analysis period,and has significant advantage in the analysis of large batch of air samples.