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目的按照职业卫生标准制定指南建立合适的工作场所中氨的采样方法,并探讨采样和分析方法能很好对接的工作场所空气中氨的测定方法。方法选用不同的采样介质,考察其采样效率,解吸效率、分析溶液对后续测定的影响;并考察建立的方法技术指标与标准要求的符合性。结果通过筛选发现,用酸性硅胶管、甲烷磺酸吸收液的短时间采样和长时间采样效率均大于95%,用甲烷磺酸解吸液解吸,平均解吸效率为91.1%;解吸液/吸收液采用分光光度法和离子色谱法分析的RSD均<4%。用2种方法对标样的测定结果都在给定的不确定度范围内。采用分光光度法和离子色谱法测定某电镀厂采集的吸收液样品,两种方法的测定结果经统计学检验,差异无统计学意义(P>0.05)。硅胶管采集的样品可以保存14 d,采样后的吸收液可以保存7 d。结论采用装有5 ml甲烷磺酸吸收液的大型多孔玻板吸收管和酸性硅胶管都可以采集工作场所空气中氨,纳氏试剂分光光度法和离子色谱法都可以用来对溶液中的氨进行定量。但考虑到对仪器的保护,采用离子色谱法检测时宜采用吸收液采样,而分光光度法检测时则两种采样方法均可使用。
Objective To establish a suitable sampling method for ammonia in the workplace according to guidelines for occupational health standards and to explore methods for the determination of ammonia in the workplace air that is well-matched by sampling and analysis methods. Methods Different sampling media were used to investigate the sampling efficiency and desorption efficiency, and the influence of solution on the subsequent determination was investigated. The compliance of the established method with the standard requirements was also investigated. Results The results showed that the short-time sampling and long-time sampling efficiency of methanesulfonic acid absorption solution were all more than 95% with acid silica gel tube. The desorption efficiency was 91.1% with desorption solution of methane sulfonic acid solution. The desorption / absorption solution RSDs were <4% for both spectrophotometry and ion chromatography. The results of the determination of the standard samples by the two methods all fall within the given range of uncertainty. The spectrophotometry and ion chromatography were used to determine the samples of absorption solution collected by a plating plant. The results of the two methods were statistically tested, with no significant difference (P> 0.05). Silicone tube samples collected can be stored for 14 days, and the sampled absorption solution can be stored for 7 days. CONCLUSIONS Ammonia from the air in the workplace can be collected using a large, porous glass-tube absorber and a sour-silica tube containing 5 ml of a methanesulfonic acid absorption solution. Both Nessler’s reagent spectrophotometry and ion chromatography can be used to quantify ammonia in solution Quantitative. However, taking into account the protection of the instrument, the use of ion exchange chromatography should be used when absorbing liquid sampling, and spectrophotometric detection of the two sampling methods can be used.