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

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.