Influence Factors and Mechanism Study on Bag Sampling Method for Determination of Reduced Sulfide Compound by Gas Chromatography-Mass Spectrometry
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ABSTRACT
BACKGROUNDReduced sulfide compound is a typical odorant characterized by high activity and is difficult to store. Therefore, suitable storage conditions are of great significance for the accurate determination of reduced sulfides.OBJECTIVESTo understand the causes of loss and deterioration of highly active reduced sulfides, and to select the optimal storage conditions.METHODSGas Chromatography-Mass Spectrometry was used to investigate the loss of the process of storing reduced sulfides by bag sampling from the following four factors, air bag material, initial concentration of reduced sulfide, reduced sulfide property, and storage time. Sample bags, Tedlar®PVF and Teflon®FEP, were used as object bags. Using 5 initial concentrations (0.001, 0.010, 0.100, 1.000 and 10.000μg/mL) of mixed reduced sulfides, 0, 2, 6, 12, 24, 48 and 72h as the storage time, using the response factor and relative recovery as the evaluation factor, and using the paired t-test and adsorption kinetics, the main factors affecting the storage effect, the mechanism of material loss and the comparison of the storage capacity of the two sampling bags were studied.RESULTSThe results show that the longer the storage time, the higher the initial concentration of the substance, and the stronger the activity of the substance, the more serious the loss. When the ambient temperature reaches 60℃, the substrate background of Tedlar®PVF is more complicated than that of Teflon®FEP. Under the same conditions, the reduced sulfides are more severely damaged during Teflon®FEP storage.CONCLUSIONSIt was suggested that:(1) the reduced sulfide be stored in shad after sampling; (2) analysis should be finished within eight hours and two hours for low and high concentration, respectively; (3) Teflon®FEP be used at high temperature and Tedlar®PVF at low temperature. The research results were beneficial to ensure the storage stability of the reduced sulfide samples, minimize the situation of odor pollution, and provide technical support for the analysis of odor pollution and the subsequent control and treatment of odor pollution.
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