固体吸附剂管采样-溶剂解吸-分光光度法测定工作场所空气中一氧化氮和二氧化氮

Measurement of nitric oxide and nitrogen dioxide in workplace air using solid adsorbent tube sampling and solvent desorption spectrophotometry

关键词: 氮氧化物  二氧化氮(NO₂)  一氧化氮(NO)  固体吸附剂管  分光光度法

Keywords: nitrogen oxide  nitrogen dioxide (NO₂)  nitric oxide (NO)  solid adsorbent tube  spectrophotometry

摘 要: 目的 建立工作场所空气中氮氧化物(NO 和 NO2)的固体吸附剂管采样-溶剂解吸-分光光度测定方法。方法 空气中的气态 NO 通过三氧化铬氧化管氧化成 NO₂; NO₂ 被三乙醇胺浸渍的 5A 分子筛吸附,溶剂解吸后生成的亚硝酸根,与对氨基苯磺酸起重氮化反应,再与盐酸萘乙二胺偶合成玫瑰红色,在 540 nm 波长下测量吸光度,进行定量。结果 亚硝酸根离子(NO^-₂)在质量浓度 0~0.70 μg/ml 时呈线性关系,相关系数 r=0.9993。方法检出限 0.004 μg/ml,定量下限 0.014 μg/ml;以采集 3 L 空气按 NO₂ 计算,最低检出浓度 0.05 mg/m³,最低定量浓度 0.19 mg/m³;以采集 12 L 空气按 NO₂ 计算,最低检出浓度 0.01 mg/m³,最低定量浓度 0.05 mg/m³。氧化管的氧化效率 92.87%~95.96%。固体吸附剂管的采样效率 95.36%~98.43%,本方法的穿透容量> 116.00 μg(300 mg 固体吸附剂),解吸效率 96.20%~98.15%,批内精密度(RSD)0.98%~4.23%, 批间精密度 1.38%~3.04%,加标回收率 95.40%~101.96%。样品在室温下至少可保存 14 d。结论 本方法适用于工作场所空气中氮氧化物的检测。

Abstract: Objective To establish a method for the determination of nitrogen oxides (NO and NO₂)in the air of workplaces by solid adsorbent tube sampling-solvent desorption-spectrophotometry. Methods Gaseous NO in the air was oxidized to NO₂ through a chromium trioxide oxidation tube. NO₂ was adsorbed by 5A molecular sieve impregnated with triethanolamine. After desorption by the solvent, the generated nitrite reacted with p-aminobenzenesulfonic acid for diazotization and then coupled with naphthylenediamine hydrochloride to form rose red color. The absorbance was measured at a wavelength of 540 nm for quantification. Results The results indicated a linear relationship of nitrite ion (NO^-₂) within the mass concentration range of 0—0.70 μg/ml, and the correlation coefficient r=0.9993. The detection limit of the method was 0.004 μg/ml, and the lower limit of quantification was 0.014 μg/ml. Based on 3 L of air collected and calculated as NO₂, the minimum detectable concentration was 0.05 mg/m³, and the minimum quantifiable concentration was 0.19 mg/m³. Based on 12 L of air collected and calculated as NO2, the minimum detectable concentration was 0.01 mg/m³, and the minimum quantifiable concentration was 0.05 mg/m³. The oxidation efficiency of the oxidation tube was 92.87%—95.96%. The sampling efficiency of the solid adsorbent tube was 95.36%—98.43%. The penetration capacity of this method was more than 116.00 μg (300 mg solid adsorbent), the desorption efficiency was 96.20%—98.15%. The intra-batch precision (RSD) was 0.98%—4.23%, and the inter-batch precision was 1.38%—3.04%, the recovery rate of standard addition was 95.40%—101.96%. The samples could be stored at room temperature for at least 14 days. Conclusion This method is applicable to the detection of nitrogen oxides in the air of the workplace.