Determination of polycyclic aromatic hydrocarbons in sewage reference sludge by liquid chromatography-atmospheric-pressure chemical-ionization mass spectrometry

Formation and identification of PAHs metabolites in marine organisms

In this study, the development of the technique APCI(+) LC/MS/MS allowed the detection of phenanthrene, pyrene and metabolites of alkyl homologs in fish bile (in situ) and in urine of crabs. Laboratory experiments were carried out exposing crabs from an unpolluted mangrove (Barra de Guaratiba) to phenanthrene, and to the alkylated homologs 1-methyl phenanthrene and 2,6,9-trimethyl phenanthrene. Urine samples were collected at 0, 24, 48, 72, and 96 h. Fishes were captured from strategic sites from Guanabara Bay. Hydroxylated metabolites of phenanthrene, epoxides, orthoquinone and glucoside conjugates were identified in both samples. The method APCI(+) LC/MS/MS showed to be effective in a preliminary assessment of phenanthrene metabolite formation, although the low concentrations of 1-methyl phenanthene and 2,6,9-trimethyl phenanthrene did not allow a systematic evaluation of data. The method, however, proved to be excellent tool for studies of PAHs metabolites due to the high selectivity, sensitivity and separation attained.

Analysis of polycyclic aromatic hydrocarbons by liquid chromatography/tandem mass spectrometry using atmospheric pressure chemical ionization or electrospray ionization with tropylium post-column derivatization

Polycyclic aromatic hydrocarbons (PAHs) with four to six rings are potent carcinogens. This study analyzed ten of the sixteen US EPA priority PAHs using reversed-phase liquid chromatography/tandem mass spectrometry (LC/MS/MS) in selected reaction monitoring mode with two ionization sources: positive atmospheric pressure chemical ionization (APCI+) or positive elecrtrospray ionization (ESI+) with tropylium post-column derivatization. Several factors were investigated, including mobile phases, stationary phases of columns and chromatographic temperature, to determine how optimal separation and sensitivity might be achieved. Methanol used as an organic mobile phase provided better sensitivities for most PAHs than acetonitrile, although some PAHs co-eluted. Acidic buffers did not increase analyte signals. Use of Restek Pinnacle II PAH columns (250 x 4.6 mm or 250 x 2.1 mm, 5 microm) with water/acetonitrile gradient at 27 degrees C made possible a good separation of the ten analytes. [M]+. were the best precursor ions in both APCI and ESI, although fluoranthene could not be detected in ESI mode when tropylium post-column derivatization was performed. [M-28]+ and [M-52]+ were the major product ions of PAHs after collision-induced dissociation, a result of neutral losses of C(2)H(4) and (C(2)H(2))(2), respectively. Chromatographic separation for PAH isomers was crucial because the mass spectra were so similar that even MS/MS could not distinguish them from each other. The recoveries of sample preparations of PAHs spiked onto air-sampling filters ranged between 77.5 and 106% with relative standard deviations between 1.1 and 15.9%. This method was validated by analyzing NIST SRM 1649a (urban dust), producing results comparable with the certified PAH concentrations. The detection limits using APCI and ESI interfaces, defined as three times the noise levels, ranged between 0.23 and 0.83 ng and between 0.16 and 0.84 ng of on-column injection, respectively.

Validated analytical strategy for the determination of polycyclic aromatic compounds in marine sediments by liquid chromatography coupled with diode-array detection and mass spectrometry

The aim of this work was to optimise and validate the experimental conditions for the analysis of 20 polycyclic aromatic compounds (PACs) [19 polycyclic aromatic hydrocarbons (PAHs) and dibenzothiophene as polycyclic aromatic sulphur heterocycle (PASH)] in marine sediments by reversed-phase high-performance liquid chromatography (LC) coupled to photodiode array detection (DAD) and to mass spectrometry (MS). The LC-MS interface used was atmospheric pressure chemical ionization (APCI) in the positive ion mode. The operational parameters of the APCI interface and MS detection, such as organic modifier, fragmentation voltage, gain, vaporizer temperature, corona current, capillary voltage, drying gas (N2) and nebulizer pressure, were studied. The sediments were subjected to microwave-assisted solvent extraction (MAE) and clean-up by solid-phase extraction (SPE). The relevance of the selected PACs lies in the fact that 16 PACs are classified by the US Environmental Protection Agency as priority pollutants; 17 PACs are detected in the Prestige oil spill; and 8 PACs are included in the priority substance list of the EU water policy. Recoveries from 47% to 102% were obtained for SRM 1944 certified reference sediment. The limits of quantitation were lower than 100 ngg(-1) dry weight for most PACs, and good precision was achieved.

Determination of polycyclic aromatic hydrocarbons and polycylic aromatic sulfur heterocycles by high-performance liquid chromatography with fluorescence and atmospheric pressure chemical ionization mass spectrometry detection in seawater and sediment samples

Two methods for determining 10 polycyclic aromatic compounds were developed. Both methods were based on high-performance liquid chromatography (HPLC), but one method used fluorescence detection, while the other used atmospheric pressure chemical ionization mass spectrometry (APCI-MS). For water analysis, solid-phase extraction (SPE) was on-line coupled to the separation system. Using a styrene-divinylbenzene copolymer (PLRP-s) as sorbent in the SPE and adding 20% of acetonitrile to the water sample before its preconcentration, recoveries were above 70% for most of the compounds. For the fluorescence method, all compounds were detected and six of them could be quantified at concentrations higher than 0.02 microg 1(-1). For the MS detection method, only seven of the compounds were detected and six were quantified at concentrations higher than 0.06 microg 1(-1). To analyse sediment samples, an extraction with dichloromethane was used and, due to the complexity of the matrix, a standard addition calibration was carried out. Seawater and sediment samples taken from the Tarragona fishing port and marina on the coast of Catalonia (Spain) were analysed, and five compounds (benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, benzo[ghi]perylene and indeno[1,2,3-cd]pyrene) were quantified in the sediment samples.

Occurrence of polycyclic aromatic hydrocarbons in sewage sludge and their contribution to its toxicity in the toxalert 100 bioassay

The contribution of polycyclic aromatic hydrocarbons (PAH) present in sewage sludge samples to toxicity was investigated. Chemical analysis using gas chromatography mass spectrometry (GC-MS) and the ToxAlert 100 bioassay, based on the inhibition to Vibrio fischeri, were applied to sludge extracts after purification by column chromatography. The levels of the 16 US EPA PAH analyzed in the sewage sludge samples varied from 17 to 2,030 microg kg(-1). In all samples examined phenanthrene was the most prominent compound. The toxicity data obtained by ToxAlert 100 can be explained by the levels and composition of the different PAH in sewage sludge samples. The present approach can contribute to evaluate the toxicity of sewage sludge.