Semi-automatic cryogenic-preconcentrator is constructed with time controlling function in preconcentration and desorption stage. GC-FPD and cryogenic-preconcentrator were to analyze gaseous sulfur compounds (hydrogen sulfide, methanethiol, dimethyl sulfide, and dimethyl disulfide) in ppbv level. The objective of this study was to offer reliable methods for sulfur gas analysis in all procedures (keeping, concentration, desorption, and detection). The cryo-concentrator was able to concentrate 4 L gas sample of 40 % relative humidity. The recovery rate of the system was in the range of 92~100 % at 30 seconds of pre-heating time, and method detection limits were shown up 0.16~0.20 ng which is able to quantify 1 ppbv level with 0.5 L gas sample. The storage time of 5 ppbv sample in polyethylene bag led to serious loss (e.g; H₂S: loss of 30% after storage 3 days).
It was estimated that the analytical bias was affected more sensitively by storage time after sampling than by cryo-injection procedures in the analysis of hydrogen sulfide and methanethiol.
The volatile odor compounds emitted form a stuffing agent production process were quantified by ATD and GC-MS, and then odor causing compounds were identified by the method of EOI using each TLV. As the results, 72 odor compounds were detected and total concentration was turned up 87.6 ppmv level. In these compounds, aldehyde group is higher 45.49 ppmv than others group, the next is turn up the order of aliphatics, alcohols, esters, ketones. The EOA of aldehyde group show up 101,720 and 97.2%, respectively, the odor causing compounds were identified each of odor 2-Octenal 28.31%, Hexanal 24.06%, Valeraldehyde 16.07%, Butyraldehyde 9.69%, Heptanal 4.97%, Propionaldehyde 4.64%, Acetaldehyde 3.31%. The TLVs of 7 major odor compounds are lower value level of 0.001∼0.0001 ppmv, odor causing even in trace level. We need to be concerned with reduction of aldehyde compounds in the odor problem by a stuffing agent production process or ironing process of the textile containing a stuffing agent.
In this study, GC-MS linked with an automatic thermal desorber was used to quantitatively analyze the odorous and volatile compounds in the gas emitted from a sewage sludge drying facility. In addition, the removal characteristics of these compounds were investigated by using a pilot-scale packed bed wet scrubber. A quantitative analysis for 58 odorous and volatile compounds in the gas was successfully achieved with GC-MS and GC-FPD. The a quantitative analysis revealed the major odorous compounds were hydrogen sulfide and acetaldehyde. In addition, D-type siloxane compounds such as octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6), were quantitatively measured. The concentrations of siloxane compounds measured in the gas were in the range of 4.54- 7.36 ppmv, higher than those in landfill gas. The average removal efficiency of the odorous and volatile compounds in a wet scrubber was 67.37%. D4, D5, and D6, which are hydrophobic compounds, were also removed by as much as 50.68%, 44.56%, and 70.26%, respectively.