Application of cluster analysis to identify sources of particulate matter in Hong Kong

Perfluorinated chemicals (PFCs) can be absorbed on fine particulate matter (PM2.5) and used as stain, water and grease repellent in a wide range of consumer products. Among the PFCs, perfluorooctane sulfonate (PFOS) and perfluoro octanoic acid (PFOA) are widely detected in human blood and serum and are of concern due to their potential toxicity. In the present experiment, fine particulate matter (PM2.5) from some northern (Beijing, Xian) and southern (Hong Kong, Guangzhou and Xiamen) cities of China were collected and analyzed for perfluoro butanoic acid (PFBA), perfluoro hexanoic acid (PFHxA), perfluoro octanoic acid (PFOA), perfluoro nonanoic acid (PFNA), perfluoro decanoic acid (PFDA), perfluoro undecanoic acid (PFUdA), perfluoro dodecanoic acid (PFDoA), perfluoro hexanesulfonate (PFHxS) and perfluoro octanesulfonate (PFOS) using liquid chromatography mass spectrometry (LC-MS/MS). The total PFCs ranged from 121.2 to 192.2pg/m3, leading by Guangzhou followed by Xian, Beijing, Xiamen and Hong Koung. Among the nine measured PFCs compounds, the level of PFHxS was below the limit of detection in all the sampling cities. The other eight PFCs (PFOS, PFDoA, PFUdA, PFDA, PFNA, PFOA, PFHxA and PFBA) were detected in all the sampling locations except PFDoA in Hong Kong samples. Human exposure estimated to PFCs for adults showed PFOS as the dominant inhaled compound representing 1.59, 1.15, 1.0 and 1.0 ng/day exposure for Hong Kong, Guangzhou, Xiamen, Beijing and Xian respectively. Results from this study contribute to our understanding of exposure pathways of PFCs to humans.Jahangirnagar University J. Biol. Sci. 5(1): 21-27, 2016 (June)

Download Full-text

Minimizing Contamination from Plastic Labware in the Quantification of C16 and C18 Fatty Acids in Filter Samples of Atmospheric Particulate Matter and Their Utility in Apportioning Cooking Source Contribution to Urban PM2.5

Atmosphere ◽

10.3390/atmos11101120 ◽

2020 ◽

Vol 11 (10) ◽

pp. 1120

Author(s):

Yuk Ying Cheng ◽

Jian Zhen Yu

Keyword(s):

Fatty Acids ◽

Hong Kong ◽

Particulate Matter ◽

Fatty Acid ◽

Stearic Acid ◽

Palmitic Acid ◽

New Method ◽

Urban Site ◽

Plastic Syringe ◽

Syringe Filter

Palmitic acid (C16:0) and stearic acid (C18:0) are among the most abundant products in cooking emission, and thus could serve as potential molecular tracers in estimating the contributions of cooking emission to particulate matter (PM2.5) pollution in the atmosphere. Organic tracer analysis in filter-based samples generally involves extraction by organic solvents, followed by filtration. In these procedures, disposable plastic labware is commonly used due to convenience and as a precaution against sample-to-sample cross contamination. However, we observed contamination for both C16:0 and C18:0 fatty acids, their levels reaching 6–8 ppm in method blanks and leading to their detection in 9% and 42% of PM2.5 samples from Hong Kong, indistinguishable from the blank. We present in this work the identification of plastic syringe and plastic syringe filter disc as the contamination sources. We further demonstrated that a new method procedure using glass syringe and stainless-steel syringe filter holder offers a successful solution. The new method has reduced the contamination level from 6.6 ± 1.2 to 2.6 ± 0.9 ppm for C16:0 and from 8.9 ± 2.1 to 1.9 ± 0.8 ppm for C18:0 fatty acid. Consequently, the limit of detection (LOD) for C16:0 has decreased by 57% from 1.8 to 0.8 ppm and 56% for C18:0 fatty acid from 3.2 to 1.4 ppm. Reductions in both LOD and blank variability has allowed the increase in quantification rate of the two fatty acids in ambient samples and thereby retrieving more data for estimating the contribution of cooking emission to ambient PM2.5. With the assistance of three cooking related tracers, palmitic acid (C16:0), stearic acid (C18:0) and cholesterol, positive matrix factorization analysis of a dataset of PM2.5 samples collected from urban Hong Kong resolved a cooking emission source. The results indicate that cooking was a significant local PM2.5 source, contributing to an average of 2.2 µgC/m3 (19%) to organic carbon at a busy downtown roadside location and 1.8 µgC/m3 (15%) at a general urban site.

Download Full-text