Title Page
Abstract
초록
Contents
1. Introduction 12
2. Materials and methods 15
2.1. Chemicals and Materials 15
2.2. Preparation of Standards and solutions 16
2.3. Liquid chromatography conditions 17
2.4. Tandem mass spectrometry parameters 18
2.5. Method validation 20
2.6. Residual BAC on different surfaces: Performed with cloth 20
2.7. Comparison of BAC migration between surfaces and between used solvents: performed with 3 gauzes instead of cloth 23
2.8. Restaurant application 24
2.9. Recovery test 27
2.10. Dermal Exposure Assessment 28
2.11. Contact angle measurements 29
3. Results and discussion 30
3.1. LC-MS-MS results 30
3.2. Calibration curves and method validation 30
3.3. Results for the quantification of residual BAC on different surfaces: In lab experiment with cloth 32
3.4. Results of ANOVA comparison of the migration rate (%) between the surfaces, and between the solvents: Experiments performed with 3 gauzes instead of cloth. 38
3.5. Results for the collection of residual BACs from restaurants and café tables 43
3.6. Recovery test results 46
3.7. Exposure Assessment results 51
3.8. Contact angle measurement results 52
4. Conclusion 54
5. References 56
6. Supplementary material 59
Table 1. Parameters used for the Liquid Chromatography. 18
Table 2. Mass chromatography conditions. 19
Table 3. BAC optimized parent ion and production (m/z) parameters. 20
Table 4. Results for the method validation. The limit of detection and limit of quantification for each BAC is shown on the left of the table 32
Table 5. Mass of BAC contained in two sprays of the used product. 33
Table 6. Migration rate(%) BAC to gauzes from the residual BAC remaining after wiped the step before (For example, the BAC migrated to the 4th gauze compared with the BAC...[이미지참조] 39
Table 7. ANOVA test results for glass, wood, and PVC surfaces. The result for IPA solvent is on the top, and the results for the water solvent are on the bottom. 40
Table 8. ANOVA test results for different BAC. The top results show the ANOVA for BAC C12 to C18 migrated to gauzes wet in IPA from the glass surface. The results below... 41
Table 9. Difference in means by the comparison with the least significant difference (LSD). Only results of the water solvent are available since only in the water case migrated BAC... 42
Table 10. Exposure calculated from sum of BAC C12, C14, C16, and C18 of the highest migrated mass from restaurant tables and from the laboratory experiments. 51
Table A. CAS number, molar mass, and chemical properties of the BAC C8 to C18. 59
Table B1. Contact angles of water on three surfaces after cleaned with ethanol and dried (Glass, PVC, and Coated wood) 60
Table B2. Contact angles of water on three surfaces after treated with BAC (Glass, PVC, and Coated wood) 61
Figure 1. Rayon dishcloth and cotton gauze samplers used in the experiment 16
Figure 2. Three surfaces (glass, merbau wood, and PVC tiles) used in the experiment. All surfaces are dense, flat, smooth, and non-porous. 16
Figure 3. The sampling method performed in this study. The surfaces were sprayed twice on an area of 900 cm². The sprayed area was wiped with a dish cloth to absorb and spread the... 23
Figure 4. The restaurant sampling process. 11 different locations were sampled; However, the picture is available only for 9 locations. 26
Figure 5. The chromatogram peaks obtained for BAC C8, BAC C10, BAC C12, BAC C14, BAC C16, and BAC C18. The BAC were eluted in order of chain length. 30
Figure 6. The calibration curve for each of the BAC. Two calibration curves are included, one of lower concentration 0.005-0.3 μM and one for larger concentrations 0.3-3 μM. 31
Figure 7. The total collected BAC from the glass surface in ng/cm². Since only BAC C12 to C18 were contained in the product, only these 4 were collected. The total collection,... 34
Figure 8. The total collected BAC from the merbau wood surface in ng/cm². Since only BAC C12 to C18 were contained in the product, only these 4 were collected. The total... 35
Figure 9. The total collected BAC from the PVC tile surface in ng/cm². Since only BAC C12 to C18 were contained in the product, only these 4 were collected. The total collection, which... 36
Figure 10. The average of the three surfaces. This was calculated after the three surfaces are regarded as the same from ANOVA analysis. Around 64 % of the BAC are collected from the... 37
Figure 11. The BAC recovery rates and the RSD values of cotton gauzes spiked with 10 nmol and extracted with 10 mL Isopropyl alcohol. The recovery rates for the extraction time of 1.5... 46
Figure 12. The recovery rate and RSD values of the cloth spiked with 20 nmol BAC and extracted with 200 mL Isopropyl alcohol. The recovery is compared for when the cloth is... 48
Figure 13. The recovery rate and RSD values for when the 3 gauzes (which were used instead of cloth in the second experiment) were spiked with 10 nmol BAC standard and extracted... 50