Douglas A. Lane

Sorbent-impregnated polyurethane foam disk for passive air sampling of volatile fluorinated chemicals.

A passive air sampler comprising a polyurethane foam (PUF) disk impregnated with XAD-4 powder has been developed. This sorbent-impregnated PUF (SIP) disk builds on previous work using PUF disk passive air samplers that have been effective in spatial air mapping studies of nonpolar hydrophobic chemicals, without the need of electricity or expensive air sampling equipment. In this study, PUF disks and SIP disks are calibrated for sampling volatile polyfluorinated chemicals--specifically, the fluorotelomer alcohols (FTOHs) and perfluoroalkyl sulfonamides (PFASs). Results demonstrate the low sorptive capacity of the PUF disk samplers, particularly for the FTOHs, with PUF disks reaching equilibrium within 1 day, after collecting approximately 0.4 and 1.2 m3 of air for 8:2 FTOH and 10:2 FTOH, respectively. This limits their use for these target compounds when time-weighted, linear-phase sampling is desired. The presence of just 0.4 g of XAD powder in the SIP disks greatly increases the sorptive capacity (by approximately 2 orders of magnitude for the FTOHs) and provides linear-phase sampling for a period of several weeks. PUF-air partition coefficients, KPUF-A, calculated for the FTOHs and PFASs are considerably lower than values predicted using previously established correlations against the octanol-air partition coefficient, KOA, demonstrating the unique partitioning behavior of the polyfluorinated chemicals. Using results from these calibration tests, air concentrations of FTOHs were derived from PUF disk samples that were deployed in 52 homes in Ottawa, Canada, during 2002/2003. These represent the first comprehensive measurements of FTOHs in indoor air in North America. Range and (geometric mean) air concentrations (pg m-3) were 261-28 900 (2070) for 8:2 FTOH and 104-9210 (890) for 10:2 FTOH. These air concentrations are orders of magnitude higher than observed for outdoor air, establishing indoor environments as important for human exposure and also as potential sources to the larger environment.

Gas and Particulate Sampling of Airborne Polycyclic Aromatic Compounds

Abstract The denuder surfaces of the gas and particle (GAP) sampler (developed at the Atmospheric Environment Service of Environment Canada) have been modified by coating with XAD-4 resin using techniques developed at Lawrence Berkeley National Laboratory (LBNL) for the lower capacity integrated organic vapor/particle sampler (IOVPS). The resulting high capacity integrated organic gas and particle sampler (IOGAPS) has been operated in ambient air at 16.7 L min−1 for a 24-hour period in Berkeley, California, USA. Simultaneous measurements were made at the same collection rate with a conventional sampler that used a filter followed by two sorbent beds. Gas and particle partition measurements were determined for 13 polycyclic aromatic hydrocarbons (PAH) ranging from 2-ring to 6-ring species. The IOGAPS indicated a higher particle fraction of these compounds than did the conventional sampler, suggesting that the conventional sampler suffered from “blow-off” losses from the particles collected on the filter.

Particle Formation and Gas/Particle Partition Measurements of the Products of the Naphthalene-OH Radical Reaction in a Smog Chamber

The formation of particles during the reaction of naphthalene with OH radicals in a smog chamber was followed by means of a scanning particle-sizing system and aerosol spectrometer probe. The initial formation of nucleation-sized particles (0.03-0.09 w m) quickly grew into an accumulation mode (0.1-3.0 w m) during the photolysis. A small nucleation mode component, however, persisted throughout the experiment, although the major portion of the mass is found in the accumulation mode at later stages in the reaction. Multichannel, annular, diffusion denuders have been used to determine the gas/particle partition factors for many of the observed products. While 1,4-naphthoquinone appears predominantly in the gas phase, the 1- and 2-naphthols and the nitronaphthalenes were found predominantly in the particle phase. Although 2-formylcinnamaldehyde, the most abundant product in the naphthalene-OH photolysis, was split approximately evenly between the gaseous and the particulate phases, the 2-formylcinnamic acid was found almost exclusively in the particle phase.

SMOG CHAMBER STUDY OF ACENAPHTHENE: GAS/PARTICLE PARTITION MEASUREMENTS OF THE PRODUCTS FORMED BY REACTION WITH THE OH RADICAL

We studied the gas/particle partitioning of the products of the reaction of acenaphthene with the OH radical in a 10 m 3 smog chamber using multichannel, annular, diffusion denuders. The results showed that most of the products are predominantly in the particulate phase. Only four compounds, such as nitroacenaphthene, preferred the gas phase. We expect that the majority of the oxidation products would be adsorbed onto atmospheric particles. A comparison of solid-phase microextraction (SPME) and denuder sampling showed that the SPME syringe takes a representative sample of both gaseous and particulate phases and therefore cannot be used to determine the gas/particle partitioning ratios of the products. Another interesting result of this study showed that methanol cannot be used for sample extraction because this solvent reacts with some of the oxidation products of acenaphthene (probably the epoxide compounds) to produce artifacts that could lead to a misinterpretation of the actual atmospheric reactions.

Photochemical Degradation of Polycyclic Aromatic Compounds. I. Naphthalene

Abstract A 10 m3 chamber has been constructed to investigate the photochemical decomposition of gas phase polycyclic aromatic compounds (PAC). The chamber was used in the static mode to investigate the products of the reaction of gas phase naphthalene with OH radicals, which were generated in the chamber through the photolysis of isopropylnitrite in the presence of NO. NO was added to the chamber to prevent the formation of ozone, the presence of which could lead to the formation of NO3 radicals and N2O5, which would then react with the naphthalene directly. The products confirmed by combined gas chromatography and mass spectrometry (GS/MS) included 1,4-naphthalenedione, 4-methyl-2H-1-benzopyran-2-one, 1(3H)-isobenzofuranone, 1,2-benzenedicarboxaldehyde, phthalic anhydride, 1-nitronaphthalene, 2-nitronaphthalene, 2-nitro-1-naphthol, and 2,4-dinitro-1-naphthol. Both 1- and 2-naphthol were detected in the gas chromatograms through comparison of relative retention times with pure standards, but they were at ...

Reactions of Methylated Naphthalenes with Hydroxyl Radicals Under Simulated Atmospheric Conditions

Abstract The gas-phase reactions of OH with 1- and 2-methylnaphthalene, 1,3- and 2,3-dimethylnaphthalene, acenaphthylene and acenaphthene were investigated under simulated atmospheric conditions in a 10m3 smog chamber. The rates of reaction, relative to naphthalene = 1.0, were 1-methylnaphthalene, 1.5; 2-methylnaphthalene, 2.1; 1,3-dimethylnaphthalene, 0.9; 2,3-dimethylnaphthalene, 0.9; acenaphthene, 2.9; and acenaphthylene, 5.8. Solid phase microextraction (SPME) in combination with gas chromatography/mass spectrometry (GC/MS) was used to analyze the organic reaction products, thus avoiding the production of artifacts observed in the previously used cold finger trapping procedure. Reaction products were mainly homologs of those formed in the reaction of naphthalene with OH radicals.

DETECTION OF KNOWN PHOTOCHEMICAL DECOMPOSITION PRODUCTS OF PAH IN PARTICULATE MATTER FROM POLLUTION EPISODES IN SEOUL, KOREA

Over the past two decades, significant efforts have been expended to identify the photochemical decomposition products of the OH radical reactions of various polycyclic aromatic compounds (PAC), such as naphthalene, methylnaphthalenes, acenaphthene and phenanthrene (1, 2, 3, 4, 5, 6, 7). Although these parent PAC are predominantly found in the gas phase, many of their oxidation products have been found largely in the particle phase (4, 7, 8). These products include diones, hydroxy-, and nitrated products as well as many products resulting from ring-opening steps. It is, or should be, the goal of every laboratory study on atmospheric processes to apply the laboratory results to real world samples. To this end, we have obtained particulate matter air samples, as well as some smog episode samples, from Seoul Korea and have searched for the known decomposition products of the above mentioned PAC. To eliminate the use of chlorinated solvents used in the extraction and analysis of particulate matter samples, we have been utilizing the direct thermal desorption of small (4 mm diameter) punches of filters followed by Multidimensional Gas Chromatography-Time of Flight Mass Spectrometry (TD-GCxGC-TOFMS) for the analysis of the desorbed compounds. So far, we have detected 14 of the known decomposition products of naphthalene, acenaphthene and phenanthrene in the Seoul pollution episode samples. These include: 1-hydroxynaphthalene, (E) 2-formylcinnamaldehyde, phthalic anhydride, phthalide, 1,2-naphthalic anhydride, 9-hydroxyphenanthrene and dibenzopyrone.

Formation of polyaromatic hydrocarbon (PAH)-quinones during the gas phase reactions of PAHs with the OH radical in the atmosphere

Environmental context Atmospheric quinones present a potential toxic risk to human health because of their involvement in the generation of reactive oxygen species. Gas phase reactions of naphthalene and phenanthrene with the OH radical are investigated in a laboratory reaction chamber to provide a preliminary assessment of the importance of the atmospheric formation of quinones. Abstract In light of the potential toxicity of quinones (QNs) to human health, previous studies carried out measurement of QNs in ambient air samples and from motor vehicle emissions to understand the characteristics and the sources of QNs in the atmosphere. The major compounds observed in the ambient air samples comprised two and three benzene rings and included polyaromatic hydrocarbon (PAH)-quinones (PAH-QNs) such as 1,2-naphthoquinone (1,2-NQ), 1,4-naphthoquinone (1,4-NQ), 9,10-phenanthrenequinone (9,10-PQ) and 9,10-anthraquinone (9,10-AQ). Although these PAH-QNs are found in vehicular emissions, they may also be formed by the photochemical reactions of gas phase PAHs with atmospheric oxidants. In this study, to allow an assessment of the importance of the atmospheric formation of PAH-QNs and to understand more clearly the sources of PAH-QNs in the atmosphere, the formation yields of PAH-QNs from the gas phase reactions of naphthalene and phenanthrene with the OH radical were observed in a laboratory reaction chamber. In addition, the phase distribution of the PAH-QNs was determined. For naphthoquinones (NQs), the formation yields of 1,4-NQ and 1,2-NQ were 1.5±0.4 and 5.1±2.7% respectively. The measured yields of PQs were 3.6±0.8% for 9,10-PQ and 2.7±1.1% for 1,4-PQ. From the measured yield data, the atmospheric formation of PAH-QNs was estimated and the importance of the atmospheric formation of PAH-QNs from the gas phase reaction of PAHs with the OH radical is discussed.

Analysis of Organic Compounds in Ambient PM 2.5 over Seoul using Thermal Desorption-comprehensive Two Dimensional Gas Chromatography-time of Flight Mass Spectrometry (TD-GCxGC-TOFMS)

Characteristics and advantages of the thermal desorption-comprehensive two dimensional gas chromatography-time of flight mass spectrometry (TD-GCxGC-TOFMS) were discussed and the organic compound`s analysis result was shown for the ambient sample collected in Seoul, Korea. Over 10,000 individual organic compounds were separated from about of aerosols in a single procedure with no sample pre-treatment. Among them, around 300 compounds were identified and classified based on the mass fragmentation patterns and GCxGC retention times. Several aliphatic compounds groups such as alkanes, alkenes, cycloalkanes, alkanoic acids, and alkan-2-ones were identified as well as 72 PAH compounds including alkyl substituted compounds and 8 hopanes. In Seoul aerosol, numerous oxidized aromatic compounds including major components of secondary organic aerosols were observed. The inventory of organic compounds in of Seoul, Korea suggested that organic aerosol were constituted by the compounds of primary source emission as well as the formation of secondary organic aerosols.

THE DETECTION OF POLYCYCLIC AROMATIC COMPOUNDS IN AIR SAMPLES BY GC×GC-TOFMS

Multidimensional Gas Chromatography-Time of Flight Mass Spectrometry is a relatively new, highly versatile and productive technique that is ideally suited for the detection of PACs in environmental samples. Air samples collected in Slocan Park in Vancouver and in Langley, BC (a semi-rural site) during the PACIFIC 2001 field study and aerosol samples from St. Anicet in Quebec (a rural site) collected in 2006 were analyzed for their PAC content. In addition to the parent PAH, many alkylated-PAH, oxygen, sulphur and nitrogen heterocyclic analogues of the parent PAH were detected. Many of the PAHs observed at these sites were also found in diesel exhaust.