氯化钙干燥-预浓缩-气相色谱-质谱法测定畜禽场环境空气中10种挥发性有机硫化物的含量

Determination of 10 Volatile Organic Sulfur Compounds in Ambient Air of Livestock and Poultry Farm by GC-MS after Dring with Calcium Chloride and Pre-Concentration

通过研究湿度、样品采集方式、样品保存时间对挥发性有机硫化物(VOSCs)测定的影响,提出了氯化钙干燥-预浓缩-气相色谱-质谱法(GC-MS)测定畜禽场环境空气中硫化氢、氧硫化碳、甲硫醇、乙硫醇、丙硫醇、丁硫醇、甲硫醚、二硫化碳、乙硫醚、二甲二硫等10种VOSCs含量的方法。畜禽场环境空气经氯化钙干燥、流量控制器采样,并在预浓缩系统中进行三级冷阱捕集。目标物在DB-624石英毛细管色谱柱上以柱升温程序进行分离,在质谱仪中以选择离子监测扫描模式检测。结果表明:当湿度为40%~50%时,硫化氢、甲硫醇、乙硫醇、丙硫醇的回收率仅为2.90%~14.5%;在流量控制器采样、氯化钙干燥条件下,各目标物的回收率均可达到80.0%以上;以一溴一氯甲烷为内标进行定量,10种VOSCs标准曲线的线性范围为2.0×10^(-5)%~2.80×10^(-4)%(硫化氢)和2×10^(-6)%~2.8×10^(-5)%(其余9种VOSCs),硫化氢的检出限(3.143s)为3.47×10^(-6)%,其余9种VOSCs的检出限为1.7×10^(-7)%~3.9×10^(-7)%;对空白样品进行3个浓度水平的加标回收试验,10种VOSCs的回收率为103%~143%,测定值的相对标准偏差(n=6)为2.3%~5.6%;方法用于分析8家畜禽养殖场堆肥粪便处环境空气,有两家养殖场未检出目标物,其他养殖场中VOSCs有不同程度地检出。

By studying the effects of humidity, sampling method and sample storage time on the determination of volatile organic sulfur compounds(VOSCs), a method for the determination of 10 VOSCs including hydrogen sulfide, carbonyl sulfide, methyl mercaptan, ethanethiol, propanethiol, butanethiol, methyl sulfide, carbon disulfide, ethyl sulfide and dimethyl disulfide, in ambient air of livestock and poultry farm by gas chromatography-mass spectrometry(GC-MS) after dring with calcium chloride and pre-concentration was proposed. The ambient air of livestock and poultry farm was dried by calcium chloride, sampled by flow antroller, and captured by three-stage cold trap in the pre-concentration system. The targets were separated on DB-624 quartz capillary column with column temperature program, and detected by mass spectrometer with selected ion monitoring scan mode. As shown by the results, when the humidity was in the range of 40%-50%, the recoveries of hydrogen sulfide, methyl mercaptan, ethanethiol and propanethiol were only in the range of 2.90%-14.5%. Under the conditions of flow controller sampling and calcium chloride drying, the recoveries of targets could reach more than 80.0%. Using bromochloromethane as the internal standard for quantification, the linear ranges of the standard curves of 10 VOSCs were 2.0×10^(-5)%-2.80×10^(-4)% for hydrogen sulfide and 2×10^(-6)%-2.8×10^(-5)% for the other 9 VOSCs, with detection limit(3.143s) of 3.47×10^(-6)% for hydrogen sulfide, and 1.7×10^(-7)%-3.9×10^(-7)% for the other 9 VOSCs. Test for recovery was made on the blank sample at 3 concentration levels, giving results of 10 VOSCs were in the range of 103%-143%, and RSDs(n=6) of the determined values ranged from 2.3% to 5.6%. This method was used to analyze the ambient air in compost feces of 8 livestock and poultry farms. The targets were not detected in two farms, and VOSCs were detected in varying degrees in the other farms.