Determination of pyridine in ambient air by headspace-gas chromatography after absorbed with dilute sulfuric acid
LIU Shaojun, FENG Jiangyan, ZONG Xiaojuan, ZHANG Zihan, REN Tianzi, XIN Kangfei, SHEN Yingyu
Hebei Huazhun Testing Technology Co., LTD., Shijiazhuang 050200, China
摘要：建立了稀硫酸吸收、顶空进样、气相色谱法测定环境空气中吡啶的方法。利用稀硫酸作为吸收液吸收环境空气中的吡啶，将吸收液转移至顶空瓶中，用氢氧化钠溶液调节吸收液的酸碱度，并加入氯化钠减少吡啶的溶解度，加热平衡后取上部空间气体注入气相色谱仪进样口分析，制作标准工作曲线，可以准确测定环境空气中吡啶的含量。最优实验条件：使用多孔玻板吸收管采集样品；采样流量为0.5 L/min；样品测定时pH需大于12；顶空加热温度为80 ℃，平衡时间为30 min，阀温度和传输线温度为120 ℃。吡啶在0.20～10.0 μg/mL质量浓度范围内线性良好，检出限为0.02 mg/m3，测定值的相对标准偏差为2.6%～8.7%（n=6），标准回收率为88.0%～105.3%。环境空气样品应在采集后立即测定，若延迟测定，应于0～4 ℃存放，可保存7 d。
Abstract：A method was established for the determination of pyridine in ambient air by dilute sulfuric acid absorption with headspace injection and gas chromatography. Pyridine in ambient air was absorbed by dilute sulfuric acid absorption solution, the absorption solution was transferred to a headspace bottle, the acidity of the absorption solution was adjusted by adding sodium hydroxide, and the solubility of pyridine was reduced by adding sodium chloride, and the upper space gas was taken into the gas chromatography inlet for analysis after heating and equilibration, and the content of pyridine in ambient air could be accurately determined by making a standard working curve. The following validations were carried out: the sample was collected using a porous glass plate absorber tube; the sampling flow rate was 0.5 L/min; pH needed to be greater than 12 when the sample was measured; the headspace heating temperature was 80 ℃, the equilibration time was 30 min, and the valve temperature and transmission line temperature were 120 ℃. The linearity of pyridine was satisfied in the mass concentration range of 0.20-10.0 μg/mL, the detection limit was 0.02 mg/m3, the relative standard deviation was 2.6%-8.7%(n=6), and the recovery was 88.0%-105.3%. The ambient air samples should be measured immediately after collection, if delay measurement required, the sample should be stored at 0-4 ℃ for a maximum of 7 d.
Keywords：pyridine; gas chromatography; headspace; absorption with dilute sulfuric acid; ambient air
LIU Shaojun，FENG Jiangyan，ZONG Xiaojuan，et al. Determination of pyridine in ambient air by headspace-gas chromatography afterabsorbed with dilute sulfuric acid[J]. Chemical Analysis and Meterage，2023，32(4)：69.