Hong Kong Premium Services and Research Laboratory

Wan Chai, Hong Kong

Hong Kong Premium Services and Research Laboratory

Wan Chai, Hong Kong

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Ho K.F.,Chinese University of Hong Kong | Ho K.F.,CAS Institute of Earth Environment | Ho S.S.H.,CAS Institute of Earth Environment | Ho S.S.H.,Desert Research Institute | And 4 more authors.
Aerosol and Air Quality Research | Year: 2013

Vehicular exhaust emissions are one of major sources of anthropogenic volatile organic compounds (VOCs) in urban areas of Pearl River Delta Region (PRDR). Six types of vehicle emission (VE)-dominated samples were collected at representative locations in Hong Kong in the winter of 2003. A total of 111 VOC species were quantified in the samples collected. n-Butane (31%) was the most abundant species in liquefied petroleum gas (LPG)-fueled VE-dominated samples, followed by propane (26%) and i-butane (25%). Toluene was the most abundant species in gasoline-fueled VE-dominated samples (16%), comprising about half of the quantified aromatic content. While ethene and ethyne have the greatest abundance in all diesel-fueled VE-dominated VOCs profiles (except at Tuen Mun Bus Depot). VOCs were also quantified at three roadside locations in Hong Kong. And ethene was the most abundant VOCs at roadside locations which accounted for 9.5 to 29% of the total quantified VOCs, except at Hong Kong Polytechnic University roadside monitoring station (PUX). Moreover, several VOCs were clearly in abundances in the roadside samples, namely toluene, ethyne, propane, i-butane, n-butane and i-pentane. Generally, strong and fair correlations were determined from the marker species of fuel vapor (i.e., LPG, gasoline, and diesel), which show significant fuel evaporation from vehicles in roadside environment of Hong Kong. Maximum incremental reactivity (MIR) was also calculated to evaluate the contributions of individual VOCs to ozone (O3) formation potential. The largest contributors to O3 production at Mong Kok roadside station (MKX) and Lok Ma Chau roadside station (LMX) were toluene (17 and 15% of the measured VOC reactivity, respectively), ethene (14 and 17% of the measured VOC reactivity, respectively), and propene (7 and 8% of the measured VOC reactivity, respectively), indicating the important roles of alkenes and aromatics in the ambient O3 formation. © Taiwan Association for Aerosol Research.


Ho S.S.H.,CAS Institute of Earth Environment | Ho S.S.H.,Desert Research Institute | Ho S.S.H.,Hong Kong Premium Services and Research Laboratory | Chow J.C.,CAS Institute of Earth Environment | And 7 more authors.
Atmospheric Environment | Year: 2011

In-injection port thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS) allows for analysis for >130 non-polar organic compounds on small quartz-fiber filter samples without extraction chemicals. TD-GC/MS has been applied to samples from long-term U.S. networks since it is cost effective and less labor intensive. However, analysis of large numbers of samples results in sensitivity reductions over time. Instrument sensitivity and reproducibility were examined after 100, 200, and 500 sample analyses. Analyses of standards between batches of heavily loaded samples from China and Japan showed signal decreases of 28-78% for major organic classes. In the GC injection port, residues can accumulate on the gold-plated seal resulting in analyte adsorption as well as elevating signal background. Decreases in signal response were 28-43% for n-alkanes, 33-45% for hopanes and steranes, 28-56% for PAHs, and 38-78% for phthalates when the gold-plated seal was not replaced after 500 TD-GC/MS sample analyses. Limits of detection (LODs) also increased by 14-76% for the targeted non-polar organic compounds. Residues trapped in the capillary column head can cause peak broadening and overlap. The GC/MS system, including the injection port and gold seal, the column head (where the eluted sample is pre-concentrated), and the ion source should be cleaned after every batch of 50-100 samples. © 2010 Elsevier Ltd.


Ho S.S.H.,CAS Institute of Earth Environment | Ho S.S.H.,Hong Kong Premium Services and Research Laboratory | Ho K.F.,CAS Institute of Earth Environment | Liu W.D.,Hong Kong Polytechnic University | And 4 more authors.
Atmospheric Environment | Year: 2011

Measurements of aldehydes and ketones are typically conducted by derivatization using sorbent cartridges coated with 2,4-dinitrophenylhydrazine (DNPH). The collected samples are eluted with acetonitrile and analyzed by high-pressure liquid chromatography coupled with an ultra-violet detector (HPLC/UV). This paper intends to examine artifacts about its suitability in identification of unsaturated carbonyls. Kinetic tests for acrolein, crotonaldehyde, methacrolein and methyl vinyl ketone (MVK) showed formations of carbonyl-DNP-hydrazone during sampling, which could further react with DNPH, resulting in undesired UV absorption products [e.g., carbonyl-DNP-hydrazone-DNPH (dimer) and 2(carbonyl-DNP-hydrazone)-DNPH (trimer)]. The dimerization and trimerization occurred for acrolein and MVK whereas only dimerization for crotonaldehyde and methacrolein. The polymerization products undoubtedly affect the integrity of the chromatogram, leading to misidentification and inaccurate quantification. Whether precautions taken during sampling and/or sample treatment could avoid or minimize this artifact has not been thoughtfully investigated. More often, such artifacts are usually overlooked by scientists when the data are reported. © 2010 Elsevier Ltd.


Tang D.,Columbia University | Li T.Y.,Chongqing Medical University | Chow J.C.,Desert Research Institute | Kulkarni S.U.,Columbia University | And 6 more authors.
Environmental Pollution | Year: 2014

In Tongliang, China, a coal-fired power plant was the major pollution source until its shutdown in 2004. We enrolled two cohorts of nonsmoking women and their newborns before and after the shutdown to examine the relationship between prenatal exposure to polycyclic aromatic hydrocarbons (PAHs) and fetal and child growth and development. PAHs were used to measure exposure to air pollution generated by the power plant. Using PAH-DNA adduct levels as biomarkers for the biologically effective dose of PAH exposure, we examined whether PAH-DNA adduct levels were associated with birth outcome, growth rate, and neurodevelopment. Head circumference was greater in children of the second cohort, compared with the first (p = 0.001), consistent with significantly reduced levels of cord blood PAH-DNA adducts in cohort II (p < 0.001) and reduced levels of ambient PAHs (p = 0.01). © 2013 Elsevier Ltd. All rights reserved.


Ho S.S.H.,CAS Institute of Earth Environment | Ho S.S.H.,Desert Research Institute | Ho S.S.H.,Hong Kong Premium Services and Research Laboratory | Ip H.S.S.,Hong Kong Premium Services and Research Laboratory | And 5 more authors.
Aerosol and Air Quality Research | Year: 2013

2,4-Dinitrophenylhydrazine (DNPH) is a typical derivatizing agent coated on sorbent cartridges for detection of carbonyl compounds at ambient levels. However, airborne oxidant of ozone (O3) can react with DNPH to form side products that can interfere with the accurate detection of carbonyls. It is the most critical interferer degrading carbonyl-DNP-hydrazone formed on the cartridge during sampling, resulting in underestimation of carbonyl concentrations; this strong oxidant can be removed by installing a denuder or scrubber coated or filled with potassium iodide (KI) upstream. The purpose of this study is to demonstrate and discuss the usage of novel KI-filled ozone traps in affecting carbonyl collection efficiency of DNPH-coated silica gel cartridges in field and laboratory settings. Results of the study showed that measured carbonyls concentrations were 4.9-13.5% lower in samples collected without any ozone traps compared to those collected with a commercially available ozone scrubber or KI denuder. Although ozone can be reduced efficiently by KI, both environmental relative humidity (RH) and byproducts formed from the oxidation of KI with ozone, namely iodine (I2) and hydroxyl ion (OH-), can inhibit derivatization kinetics and contribute to degradation of the carbonyl-DNP-hydrazones formed during sampling. Placement of an acid-permeated polyethylene filter between the ozone scrubbers and the DNPH-coated cartridge notably improved carbonyl collection efficiency by neutralizing the byproduct OH-. End-users of the DNPH method should consider these findings and evaluate the performance of ozone scrubbers accordingly during sampling events. © Taiwan Association for Aerosol Research.


Ho S.S.H.,CAS Institute of Earth Environment | Ho S.S.H.,Desert Research Institute | Ho S.S.H.,Hong Kong Premium Services and Research Laboratory | Ip H.S.S.,Hong Kong Premium Services and Research Laboratory | And 6 more authors.
Journal of the Air and Waste Management Association | Year: 2013

A pilot hazardous airborne carbonyls study was carried out in Hong Kong and the Mainland of China. Workplace air samples in 14 factories of various types of manufacturing and industrial operations were collected and analyzed for a panel of 21 carbonyl compounds. The factories can be classified into five general categories, including food processing, electroplating, textile dyeing, chemical manufacturer, and petroleum refinery. Formaldehyde was invariably the most abundant carbonyl compound among all the workplace air samples, accounting for 22.0-44.0% of the total measured amount of carbonyls on a molar basis. Acetone was also found to be an abundant carbonyl in workplace settings; among the selected industrial sectors, chemical manufacturers' workplaces had the highest percentage (an average of 42.6%) of acetone in the total amount of carbonyls measured in air. Benzaldehyde accounted for an average of 20.5% of the total amount of detected carbonyls in electroplating factories, but its contribution was minor in other industrial workplaces. Long-chain aliphatic carbonyls (C6-C10) accounted for a large portion (37.2%) of the total carbonyls in food-processing factories. Glyoxal and methylglyoxal existed at variable levels in the selected workplaces, ranging from 0.2% to 5.5%. The mixing ratio of formaldehyde ranged from 8.6 to 101.2 ppbv in the sampled workplaces. The observed amount of formaldehyde in two paint and wax manufacturers and food-processing factories exceeded the World Health Organization (WHO) air quality guideline of 81.8 ppbv. Carcinogenic risks of chronic exposure to formaldehyde and acetaldehyde by the workers were evaluated. The lifetime cancer hazard risks associated with formaldehyde exposure to male and female workers ranged from 2.01 × 10-5 to 2.37 × 10-4 and 2.68 × 10-5 to 3.16 × 10-4, respectively. Such elevated risk values suggest that the negative health impact of formaldehyde exposure represents a valid concern, and proper actions should be taken to protect workers from such risks. Many carbonyl species (e.g., formaldehyde, acetaldehyde, and acrolein) are air toxins and they pose public health risks. The scope of this investigation covers 21 types of carbonyls based on samples collected from 14 different workplaces. Findings of the study will not only provide a comprehensive assessment of indoor air quality with regard to workers' healthy and safety, but also establish a theoretical foundation for future formulation of intervention strategies to reduce occupational carbonyl exposures. No similar study has been carried out either in Hong Kong or the Mainland of China. © 2013 Copyright 2013 A&WMA.


Ho S.S.H.,CAS Institute of Earth Environment | Ho S.S.H.,Desert Research Institute | Ho K.F.,CAS Institute of Earth Environment | Ho K.F.,Hong Kong Polytechnic University | And 7 more authors.
Journal of the Air and Waste Management Association | Year: 2012

Vehicular emission (VE) is one of the important anthropogenic sources for airborne carbonyls in urban area. Six types of VE-dominated samples were collected at representative locations in Hong Kong where polluted by a particular fueled type of vehicles, including (i) a gas refilling taxis station (liquefied petroleum gas [LPG] emission); (ii) a light-duty passenger car park (gasoline emission); (iii) a minibus station (diesel emission); (iv) a single-deck-bus depot (diesel emission); (v) a double-deck-bus depot (diesel emission); and (vi) a whole-food market entrance for light- and heavy-duty vehicles (diesel emission). A total of 15 carbonyls in the samples were quantified. Formaldehyde was the most abundant carbonyl among the VE-dominated samples, and its contribution to the total quantified amount on a molar basis ranged from 54.8% to 60.8%. Acetaldehyde and acetone were the next two abundant carbonyls. The carbonyls were quantified at three roadside locations in Hong Kong. The highest concentrations of formaldehyde and acetaldehyde, 22.7 ± 8.4 and 6.0 ± 2.8 μg/m3, respectively, were determined in the samples collected at a main transportation gate for goods between Hong Kong and Mainland China. The total quantified carbonyl concentration, 37.9 ± 9.3 μg/m3, was the highest at an entrance of a cross-harbor tunnel in downtown area. The theoretical carbonyls compositions of the three roadside locations were estimated according to the VE-dominated sample profiles and the statistics on vehicle numbers and types during the sampling period. The measured compositions of formaldehyde were much higher than the theoretical compositions in summer, demonstrating that photochemical reactions significantly contributed to the formaldehyde production in the roadsides. © 2012 Copyright 2012 A&WMA.


Wang B.,Hong Kong Polytechnic University | Wang B.,Concordia University at Montréal | Hang Ho S.S.,CAS Institute of Earth Environment | Hang Ho S.S.,Desert Research Institute | And 6 more authors.
Aerosol and Air Quality Research | Year: 2012

Environment tobacco smoke (ETS) is an important source of anthropogenic pollution in indoor environments. This research reports an environmental chamber study of pollutants released from ETS generated by smoking cigarettes in the chamber. Six cigarettes samples sold in Hong Kong and China were characterized. Gaseous pollutants: carbon monoxide (CO), sulphur dioxide (SO2), nitric oxide (NO), nitrogen dioxide (NO2), methane (CH4), non-methane hydrocarbon (NMHC), carbonyls and volatile organic compounds (VOCs); and particulate matter (PM), including organic carbon (OC), elemental carbon (EC) and total carbon (TC), were determined using online and offline analytical methods during smoking and post-smoking periods. Acetaldehyde, acetone and formaldehyde were the three most abundant carbonyls. A total of 18 aromatic and chlorinated VOCs were quantified. Among these, benzene and toluene were the two most abundant VOCs. OC was more dominant (> 93% of TC) than EC. The amounts of tar and nicotine in the cigarettes could have a direct correlation with the PM emitted. Menthol, an additive in cigarettes, could also contribute to the ETS pollutants. The indoor ETS could be removed by a higher air exchange rate, which would also minimize secondary VOC formation. © Taiwan Association for Aerosol Research.


Wu F.,CAS Institute of Earth Environment | Ho S.S.H.,CAS Institute of Earth Environment | Ho S.S.H.,Hong Kong Premium Services and Research Laboratory | Sun Q.,East China Normal University | Ip S.H.S.,Hong Kong Premium Services and Research Laboratory
Terrestrial, Atmospheric and Oceanic Sciences | Year: 2011

Twenty-seven samples of typical loess and paleosol strata collected in nine different regions of the Chinese Loess Plateau (CLP) were fractionated into PM1.0, PM2.5, PM10 and Total Suspended Particulates (TSP) (particulate matter with aerodynamic diameters less than 1.0, 2.5, 10 and ~30 μm, respectively) by a resuspension chamber at the Desert Research Institute (DRI; Reno, NV, United States). The amounts and isotope ratios of lead (Pb) were quantified in the loess samples. Our size-segregated analysis demonstrated that the Pb isotopic composition in the loess-paleosol deposits was preserved after grain-size sorting and that therefore the isotope ratio can serve as a proxy for source tracing. A similar pattern of Pb isotope ratios was observed for sediment collected from potential source regions and the loess samples suggested that the Gobi and deserts in southern Mongolia and northern China are major sources for the deposits in the CLP. No significant deviation of Pb isotope amount was found between the nine samples of loess and paleosol strata, implying the stability of loess sources during the glacial and interglacial regime.


Huang Y.,Hong Kong Polytechnic University | Hang Ho S.S.,CAS Institute of Earth Environment | Hang Ho S.S.,Desert Research Institute | Ho K.F.,CAS Institute of Earth Environment | And 3 more authors.
Analytical Methods | Year: 2012

Biogenic volatile organic compounds (BVOCs) in household cleaning products play key roles in indoor air quality (IAQ) because they are precursors for secondary pollutants formation. An accurate and rapid analytical technique for their measurement is of importance. This paper describes an optimization of a method for solid-phase microextraction (SPME) coupled with gas chromatography/mass spectrometry (GC-MS) for the determination of BVOCs. SPME fibers coated with Carboxen-PDMS are used to collect 12 individual BVOCs under standard conditions with a short exposure time of 5 min. Parameters influencing the extraction processes including sampling time, temperature and relative humidity are also investigated. All of the targeted BVOCs are shown to have limits of detection (LODs) in mixing ratios ranging from 0.31-0.50 ppbv, which are two magnitudes better than the LODs reported. The method precisions are between 1.1% and 6.7%. Comparison studies were carried out on a set of four floor cleaner extracts using the SPME method and traditional liquid injection method. Good agreement of the targeted BVOCs by the two methods was demonstrated. Our results indicated that SPME can serve as a simple and rapid sample collection approach to quantify BVOCs accurately and precisely in the indoor environment. © 2012 The Royal Society of Chemistry.

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