Interlaboratory comparison of HPLC-fluorescence detection and GC/MS: analysis of PAH compounds present in diesel exhaust

Temperature Effects on Retention and Separation of PAHs in Reversed-Phase Liquid Chromatography Using Columns Packed with Fully Porous and Core-Shell Particles

Effects of temperature on the reversed-phase chromatographic behavior of PAHs were investigated on three columns. The first was the recent C18column (250 mm × 4.6 mm) packed with 5 µm core-shell particles while the others were more conventional C18columns (250 mm × 4.6 mm) packed with fully porous particles. Among the 16 PAHs studied, special attention has been paid to two pairs of PAHs, fluorene/acenaphthene and chrysene/benzo[a]anthracene, which often present coeluting problems. Due to the low surface area of the core-shell particles, lowest retention time of each PAH was highlighted and effects of the temperature on the separation of PAHs were negligible in regard to those using columns packed with fully porous particles. For each PAH studied, it was demonstrated that peaks were symmetrical and may be considered as Gaussian peaks when the column packed with core-shell particle was employed. In the best condition, the separation of PAHs was conducted at 16°C under very low pressure values (670–950 psi = 46–65 bars). Depending on PAHs, the limit of detection ranged from 0.88 to 9.16 μg L−1. Analysis of spiked acetonitrile samples with PAHs at 10 and 50 µg L−1and tap water at 10 µg L−1gave very good recoveries (94%–109.3%) and high precision (1.1%–3.5%).

Genotoxic bioactivation of constituents of a diesel exhaust particle extract by the human lung

The ability of the human lung to catalyze genotoxic bioactivation of constituents of diesel exhaust particle (DEP) extract (DEPE) and the identity of the lung enzymes involved in the bioactivation were investigated using human lung tissues obtained from surgical resections. Genotoxicity was determined by lung S9-catalyzed mutagenicity of DEPE constituents to Salmonella typhimurium TA98NR in the Ames test and by DEPE-induced pneumocyte DNA damage response as determined by γH2Ax expression in ex vivo tissues. S9 was prepared from lung explants treated ex vivo with either DEPE to induce pulmonary enzymes (DEPE-S9) or vehicle only (CON-S9). TA98NR served as the tester strain for the purpose of enhancing and minimizing the contribution of lung S9 and Salmonella, respectively, to DEPE bioactivation. DEPE-S9 was 2.2-fold more active than CON-S9 or rat liver S9 in DEPE bioactivation and the bioactivation was inhibited 58, 45, 22, and 16% by α-naphthoflavone, dicumarol, ketoconazole, and ticlopidine, respectively. Alveolar S9 was less active than bronchioalveolar S9 in DEPE bioactivation. DEPE and diesel exhaust particles (DEP) induced γ-pH2Ax expression in pulmonary cells. Pulmonary CYP1A1 and NQO1 were induced by DEPE treatment, with the constitutive and induced CYP1A1 distributed throughout all peripheral lung regions, whereas NQO1 was limited in distribution to bronchiolar epithelium. The results show that the human lung is highly active in catalyzing genotoxic bioactivation of diesel emission constituents and that CYP1A and NQO1 play major roles in the reaction. The findings underscore the usefulness of human lung tissues in studies of the pneumotoxicity potential of chemicals to humans.

Polycyclic Aromatic Hydrocarbons in Air

Policiklički aromatski ugljikovodici (PAU) spojevi su koji se sastoje od dva ili više kondenziranih aromatskih prstenova. Nastaju prilikom nepotpunog izgaranja ili pirolize organskih tvari. Dokazano je da neki PAU imaju kancerogena, a neki mutagena svojstva, pa je stoga potrebno kontinuirano pratiti koncentracije PAU u zraku, vodi i tlu, te pokušati sanirati izvore PAU. PAU s dva ili tri aromatska prstena postojani su u plinovitoj fazi, dok se PAU s više aromatskih prstenova nalaze u zraku uglavnom vezani na čestice. Visoke koncentracije PAU prisutne su u atmosferi urbanih područja, a najviše su zimi kada su pojačane emisije iz kućnih ložišta. U ljetno doba koncentracije su niže jer je većina policikličkih aromatskih ugljikovodika nestabilna na visokim temperaturama, a osim toga dolazi do njihove oksidacije i fotooksidacije. Metode mjerenja PAU u zraku uključuju uzorkovanje prosisavanjem na filterski papir ili kruti adsorbens, ekstrakciju i kromatografsku analizu. U ovom radu prikazani su rezultati mjerenja benzo[a]pirena (BaP) kao glavnog predstavnika PAU na nekim lokacijama u svijetu. Razine BaP u svijetu uspoređene su s rezultatima mjerenja provedenim do sada u Hrvatskoj.

Results of interlaboratory comparisons of column percolation tests

Laboratory leaching tests may be used for source term determination as a basis for risk assessment for soil-groundwater pathway (leachate forecast) on contaminated sites in Germany. Interlaboratory comparisons on the evaluation of the reproducibility of column percolation tests were conducted within the framework of an integrated R+D program using three waste reference materials. The interlaboratory comparisons of column percolation tests showed good reproducibility of the results for inorganic and organic parameters as well as for the accompanying parameters. This is due to the stipulations concerning the time of contact between leachant and sample material as well as the sample placement in the columns. Different column dimensions used by the participants of the interlaboratory comparisons did not have any substantial influence on the column test results.

A multi-dimensional high performance liquid chromatographic method for fingerprinting polycyclic aromatic hydrocarbons and their alkyl-homologs in the heavy gas oil fraction of Alaskan North Slope crude

We report an offline multi-dimensional high performance liquid chromatography (HPLC) technique for the group separation and analysis of PAHs in a heavy gas oil fraction (boiling range 287-481 degrees C). Waxes present in the heavy gas oil fraction were precipitated using cold acetone at -20 degrees C. Recovery studies showed that the extract contained 93% (+/-1%; n=3) of the PAHs that were originally present while the wax residue contained only 6% (+/-0.5%; n=3). PAHs present in the extract were fractionated, based on number of rings, into five fractions using a semi-preparative silica column (normal-phase HPLC). These fractions were analyzed using reverse-phase HPLC (RP-HPLC) coupled to a diode array detector (DAD). The method separated alkyl and un-substituted PAHs on two reverse-phase columns in series using an acetonitrile/water mobile phase. UV spectra of the chromatographic peaks were used to differentiate among PAH groups. Further characterization of PAHs within a given group to determine the substituent alkyl carbon number used retention time matching with a suite of alkyl-PAH standards. Naphthalene, dibenzothiophene, phenanthrene and fluorene and their C1-C4 alkyl isomers were quantified. The concentrations of these compounds obtained using the current method were compared with that of a GC-MS analysis obtained from an independent oil chemistry laboratory.

Optimization of the procedure for the determination of polycyclic aromatic hydrocarbons and their derivatives in fish tissue: Estimation of measurements uncertainty

Three alternative procedures were employed for the isolation of polycyclic aromatic hydrocarbons (PAHs; 15 of 16 US EPA priority pollutants and benzo[e]pyrene), their methyl-derivatives and sulphur analogues from fish tissue: (1) Soxhlet extraction, (2) batch extraction enhanced by sonication, and (3) saponification of the sample followed by re-extraction of analytes into hexane. Soxhlet extraction using hexane-acetone (1:1, v/v) was the most efficient extraction technique, with analyte recoveries in the range 70-108%. Within optimization of the clean-up step, several types of gel permeation chromatography (GPC) systems were tested: two types of polystyrene divinylbenzene copolymer gels (PSDVB), both 'soft' gel type (Bio-Beads S-X3) and 'rigid' gels type (PL gel and Envirogel) in combination with various mobile phases were compared. Bio-Beads S-X3 and mobile phase chloroform were the most appropriate for purifying of crude extracts before the final determinative step. High-performance liquid chromatography with fluorimetric detection (HPLC/FLD) was used for identification and quantification of PAHs in purified fish extracts. The uncertainties of PAHs measurements were estimated by employing two alternative approaches. Both provided similar results: the expanded uncertainties obtained for individual PAHs by the 'top-down' approach were in the range 9-53%, their values resulting from application of the 'bottom-up' approach were in the range 16-52%.

The organic composition of diesel particulate matter, diesel fuel and engine oil of a non-road diesel generator

Diesel-powered equipment is known to emit significant quantities of fine particulate matter to the atmosphere. Numerous organic compounds can be adsorbed onto the surfaces of these inhalable particles, among which polycyclic aromatic hydrocarbons (PAHs) are considered potential occupational carcinogens. Guidelines have been established by various agencies regarding diesel emissions and various control technologies are under development. The purpose of this study is to identify, quantify and compare the organic compounds in diesel particulate matter (DPM) with the diesel fuel and engine oil used in a non-road diesel generator. Approximately 90 organic compounds were quantified (with molecular weight ranging from 120 to 350), which include alkanes, PAHs, alkylated PAHs, alkylbenzenes and alkanoic acids. The low sulfur diesel fuel contains 61% alkanes and 7.1% of PAHs. The identifiable portion of the engine oil contains mainly the alkanoic and benzoic acids. The composition of DPM suggests that they may be originated from unburned diesel fuel, engine oil evaporation and combustion generated products. Compared with diesel fuel, DPM contains fewer fractions of alkanes and more PAH compounds, with the shift toward higher molecular weight ones. The enrichment of compounds with higher molecular weight in DPM may be combustion related (pyrogenic).