ABSTRACT Quality assurance (QA) of VOC analysis and its relationship with odor evaluation techniques Shin Young Park Department of Earth and Environmental Sciences The Graduate School of Sejong University This research aimed the improvement of the quality assurance (QA) technique for the volatile or...
ABSTRACT Quality assurance (QA) of VOC analysis and its relationship with odor evaluation techniques Shin Young Park Department of Earth and Environmental Sciences The Graduate School of Sejong University This research aimed the improvement of the quality assurance (QA) technique for the volatile organic compounds (VOC). In addition, the relationship between air dilution sensory (ASD) test and instrumental method for odor substances was evaluated. This research consists of 3 chapters. In Chapters 1, attempts were made to evaluate the uncertainties involved in the VOC analysis through a combined application of GC/FID with air server/thermal desorption (AS/TD) system. In Chapter 1,1 the known amounts of VOC standard gases including benzene, toluene, xylene, and styrene (called as BTXS) were prepared at four different concentrations (4, 8, 20, and 40 ppb). Each of these four standard gases was analyzed individually to derive their respective calibration results. The results were then compared across four different compounds. According to this comparison, differences in calibration patterns were not significant enough within the selected concentration range of 4~40 ppb. It was also observed that the loss of styrene standard, when compared across four different compounds, was more apparent than the other VOCs investigated simultaneously. In Chapter 1.2 the known amounts of BTXS standard gases prepared at 10, 20, 50, and 100 ppb were used to draw the calibration curves respective concentration. The loss of standard samples occurred more prominently with decreasing standard concentrations (e.g., one prepared at 10 ppb) with the most noticeable loss from the heaviest compound styrene. In this study, An ancillary experiment was also conducted to evaluate the compatibility of standards between gaseous (using Tedlar bag) liquid phases (using tube method). Based on this comparative analysis, the recovery ratio between two standard types (gas/liquid) was computed: 56 (benzene), 42 (toluene), 31 (p-xylene) and 25% (styrene). In Chapter 2 and 3, an attempt was made to assess the relationship between air dilution sensory (ASD) test and instrumental detection method for individual odorous compounds. The results of instrumental analyses from 46 samples were compared to odor strength expressed as ‘dilution to threshold (D/T)’ ratio after modification to several parameters such as: the sum of odor concentration (SOC), sum of odor quotient (SOQ) and sum of odor intensity (SOI). When we compared D/T values with the modified odor criteria, Pearson coefficient of SOC, SOQ, and SOI were 0.556 (p=5.83E-05), 0.911 (p=9.64E-19) and 0.847 (p=8.93E-14), respectively. The results of this study thus suggest that the conc.’n values were strongly correlated with odor strength measured by olfactometry method. In chapter 4, the analysis of malodor compounds was made using a total of 70 samples collected from three industrial sectors which include: food & beverage (F), waste treatment and cleaning (W), and miscellaneous company (X). The results converted into three odor indices (the odor concentration (OC), odor quotient (OQ) and odor intensity (OI)) were used to statistically sort out the relative contribution of individual odorous component. The results of multiple regression analysis between D/T ratio value and instrumental concentration (of individual 12 compounds) indicate that butyraldehyde, CH3SH, NH3 and H2S are the major odorous compounds that may require more control for the industrial area, investigated in this study.
ABSTRACT Quality assurance (QA) of VOC analysis and its relationship with odor evaluation techniques Shin Young Park Department of Earth and Environmental Sciences The Graduate School of Sejong University This research aimed the improvement of the quality assurance (QA) technique for the volatile organic compounds (VOC). In addition, the relationship between air dilution sensory (ASD) test and instrumental method for odor substances was evaluated. This research consists of 3 chapters. In Chapters 1, attempts were made to evaluate the uncertainties involved in the VOC analysis through a combined application of GC/FID with air server/thermal desorption (AS/TD) system. In Chapter 1,1 the known amounts of VOC standard gases including benzene, toluene, xylene, and styrene (called as BTXS) were prepared at four different concentrations (4, 8, 20, and 40 ppb). Each of these four standard gases was analyzed individually to derive their respective calibration results. The results were then compared across four different compounds. According to this comparison, differences in calibration patterns were not significant enough within the selected concentration range of 4~40 ppb. It was also observed that the loss of styrene standard, when compared across four different compounds, was more apparent than the other VOCs investigated simultaneously. In Chapter 1.2 the known amounts of BTXS standard gases prepared at 10, 20, 50, and 100 ppb were used to draw the calibration curves respective concentration. The loss of standard samples occurred more prominently with decreasing standard concentrations (e.g., one prepared at 10 ppb) with the most noticeable loss from the heaviest compound styrene. In this study, An ancillary experiment was also conducted to evaluate the compatibility of standards between gaseous (using Tedlar bag) liquid phases (using tube method). Based on this comparative analysis, the recovery ratio between two standard types (gas/liquid) was computed: 56 (benzene), 42 (toluene), 31 (p-xylene) and 25% (styrene). In Chapter 2 and 3, an attempt was made to assess the relationship between air dilution sensory (ASD) test and instrumental detection method for individual odorous compounds. The results of instrumental analyses from 46 samples were compared to odor strength expressed as ‘dilution to threshold (D/T)’ ratio after modification to several parameters such as: the sum of odor concentration (SOC), sum of odor quotient (SOQ) and sum of odor intensity (SOI). When we compared D/T values with the modified odor criteria, Pearson coefficient of SOC, SOQ, and SOI were 0.556 (p=5.83E-05), 0.911 (p=9.64E-19) and 0.847 (p=8.93E-14), respectively. The results of this study thus suggest that the conc.’n values were strongly correlated with odor strength measured by olfactometry method. In chapter 4, the analysis of malodor compounds was made using a total of 70 samples collected from three industrial sectors which include: food & beverage (F), waste treatment and cleaning (W), and miscellaneous company (X). The results converted into three odor indices (the odor concentration (OC), odor quotient (OQ) and odor intensity (OI)) were used to statistically sort out the relative contribution of individual odorous component. The results of multiple regression analysis between D/T ratio value and instrumental concentration (of individual 12 compounds) indicate that butyraldehyde, CH3SH, NH3 and H2S are the major odorous compounds that may require more control for the industrial area, investigated in this study.
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