In this study, a series of experiments were carried out to measure temporal stability of trimethylamine (TMA) in two different bag sampler types (polyvinyl fluoride bag (PVF) and polyester aluminum bag (PEA)) as a function of storage time. To this end, temporal variability of TMA was measured using its standard gas samples up to 4 days. For the purpose of comparison, storability of TMA was tested between PVF and PEA. To this end, standard gas samples were prepared at two concentration levels of 1 and 10 ppm. The results of this study indicate that the reduction of TMA levels generally increased with the extension of the storage time. Although both bag types showed moderate losses of TMA, differences between bag types (PVF and PEA) were likely to be less significant than those of concentration levels.
Odorous pollutants emitted from the manufacturing process of TFT-LCD were investigated to prepare the odor control plan. Odor measurements in the workplace of clean room were also carried out. The odorous pollutants detected in the organic and acid gas emission duct were acetone, acetic acid, IPA, nbutylacetate, PGMEA, cyclohexane, which were chemicals used for LCD manufacturing. Especially, acetic acid was turned out to one of the major odor substances in the acid gas emission duct because of its low odor threshold value. No odorous pollutants were detected in the toxic gas emission duct. Some organic gases detected in the clean room were due to the leakage from chemical containers or LCD devices.
In this study, emission characteristics of odorants from boiled egg samples were measured through time between fresh and decayed status. Air samples released from boiled egg were collected and analyzed five different periods during the whole experimental period set for 9 days. The concentrations of reduced sulfur compounds (RSC), carbonyl compounds (CC), and NH₃ were generally higher than others like volatile organic compounds over the entire period. Among target compounds, the concentration of H₂S recorded the maximum value of 3.65 ppm immediately after boiling which indicates its maximum contribution as odorant in fresh stage. In addition, some odorants (i.e. CH₃SH, AA, PA, BA, and VA) were detected in the range of 7.52 to 50.8 ppb. Emission of most odorants generally decreased after 1 day of boiling, although their concentrations increased again after 3 days to reach the peak values after 6 days. The dilution-to-threshold (D/T) ratio measured by air dilution sensory test samples between fresh and decayed egg showed patterns similar to H2S. In addition, the result of correlation analysis indicated that there is a strong relationship (p<0.01) between complex odor and H₂S.
A new method using anion generating paint was tested to decrease the concentration of volatile organic compound gas which is the main cause of sick house syndrome in living atmosphere. The method can be widely applied with low cost because the anion generating paint uses the cheap and abundant aluminosilicate mineral as raw materials and maintains the ability to remove the VOCs in dark condition, which was the main demerit of conventional method using TiO2 photo catalyst. The effect of raw mineral treatment on the efficiency of VOCs removal was studied by applying the prepared anion generating paint on specimen surface and monitoring the content of VOCs within controlled box for 24 hours. The content of formaldehyde and toluene was decreased by 88.9% and 72.2%, respectively. The result of field test done in actual living apartment showed the removal ability of 92.2% for formaldehyde, 10% for benzene, 95.9% for toluene, 74.4% for ethylbenzen, 73.8% for p-xylen, and 83.7% for styrene. The concentration of other VOCs were also decreased to below the standard level recommended by Ministry of Environment.
This study aims to evaluate the relationship with the concentration and dilution factor using the Air Dilution Olfactory Method, which is suggested in the Standard Method of Odor Compounds, by measuring dilution factor for 4 types of sulfur compounds, ammonia, and trimethylamine. For the measurement, 13 panelists were selected by several criteria through a panel test. Panelists chosen for their closely similar sensitiviyies provide more reproducible values. The estimation showed that the correlation of the concentration with dilution factor for the 6 compounds can be reasonably expressed by the equation logC=AfㆍlogD+F (Af: material costant, F: constant). The result of this study is suggested to be used as a base data for research on measures to improve the regulation standards for complex odor concentration on site boundary in operation, as well as a correlation between the concentration and dilution factor for the designated foul odor substances, and their characteristics.
Since 2011, proficiency test for the air dilution olfactory method started in Korea for the evaluation of the authorized odor inspection agencies’ analysis skill. For this purpose, sulfur compounds of PTMs (proficiency test materials) were made and investigated for the application to the proficiency test as a complex malodor sample. Time stability and homogeneity between samples were analysed for the PTM which was made with 10 ppm of DMS and 10 ppm of DMDS. As the results, the stability of sample concentration with GC analysis was shown around 6%RSD through the time of 6~48 hr. In addition, dilution number during the same test period appeared almost stable, less than 6%RSD in air dilution olfactory method. The reproducibility results of four laboratories showed very similar results except one lab which was caused by the elder panel characteristics.