Measurement of high-molecular-weight polycyclic aromatic hydrocarbons in soils by particle beam high-performance liquid chromatography-mass spectrometry.

Polycyclic aromatic hydrocarbons (PAHs) comprise a class of potentially hazardous com- pounds of concern to the U.S. EPA. The application of particle-beam (PB) liquid chromatography-mass spectrometry (LC-MS) to the measurement of high-molecular-weight PAHs was investigated. Instrument performance was evaluated for 16 PAHs in the molecular weight range 300-450 u. The PAHs were separated by reverse-phase high-performance liquid chromatography via a polymeric octadecylsilica (C-18) packing and gradient elution with methanol-tetrahydrofuran. On-column instrument detection limits, as measured by selected ion monitoring on the singly charged molecular ion of each PAH, were found to be 0.15-0.60 ng for PAHs with molecular weights up to 352 u and 2-4 ng for PAHs with molecular weights greater than 352 u. Instrument response was generally linear for PAHs with molecular weights 300-352 u and generally nonlinear for PAHs with molecular weights greater than 352 u. The PB electron impact mass spectra of the PAHs were found to vary with the ion distribution ratio of the singly charged molecular ion to the doubly charged molecular ion, dependent on molecular weight, ion source temperature, and concentration. Analysis by PB LC-MS was applied to extracts of PAH-spiked soil and a PAH-contaminated soil from the Pacific Northwest. Target analyte concentrations in the PAH-contaminated soil ranged from 0.85 to 84 µg/g. Quantitative estimates for nontarget PAHs also were determined. Analysis of a second soil extract from a hazardous waste site in the northeast part of the United States displayed isomeric patterns of high-molecular-weight PAHs similar to those of the Pacific Northwest extract.

Evidence for thermal decomposition contributions to the mass spectra of chlorinated phenoxyacid herbicides obtained by particle beam liquid chromatography mass spectrometry.

The spectral quality of a group of chlorinated phenoxyacid herbicides has been shown to degrade under certain conditions upon introduction into the mass spectrometer by a particle beam interface. Experiments were performed to investigate these changes in spectra. Normalized ion chromatograms were generated for the herbicides, and the results showed a broadening of the profiles of some ions, indicating a longer residence time in the ion source. These ions were postulated as coming from the ionization of thermal degradation products from the herbicides. The generation of these ions was dependent on ion source temperature, analyte concentration, and, by implication, ion source cleanliness. Tandem mass spectrometry experiments were performed on these ions from the herbicides and ions from the corresponding phenols. The tandem mass spectra of the ions from the herbicides were similar to the tandem mass spectra of the ions from the phenols. Therefore, it appears that the particle beam mass spectra of the chlorinated phenoxyacid herbicides are composite spectra with contributions from the gas phase ionization of the parent herbicides and thermal decomposition products.

Environmental semivolatiles and nonvolatiles analysis by hyphenated spectral techniques.

Environmental sample extracts contain a variety of volatile and nonvolatile organic compounds exhibiting a range of polarities and concentrations. Although gas chromatography/mass spectrometry (GC/MS) is the method of choice thus far for such analyses, this technique used alone cannot adequately characterize the volatiles in such samples and is not amenable to environmental nonvolatiles. A more complete characterization of environmental and hazardous waste samples is required to assess the dangers posed to the nation's groundwater by hazardous waste dumps. Online spectral confirmation by directly linked GC/Fourier transform infrared (FTIR)/MS is shown to provide useful structural information on environmental volatiles in hazardous wastes, even when the analyte's spectrum is not in either spectral database. This information can lead to biological-hazard estimation. The diffuse reflectance Fourier transform infrared (DRIFT) technique, used in conjunction with thermospray MS or fast atom bombardment (FAB) MS, provides confirmed identifications or confirmed compound class assignments of organic nonvolatiles in solid wastes. This is believed to be the first report of spectral confirmation (identification or functionality) of organic volatiles and nonvolatiles in environmental samples.

Characterization of doxylamine and pyrilamine metabolites via thermospray/mass spectrometry and tandem mass spectrometry.

Analysis of doxylamine N-oxide and pyrilamine N-oxide as synthetic standards and biologically derived metabolites by thermospray mass spectrometry (TSP/MS) provided [M + H]+ ions for each metabolite. TSP/tandem mass spectrometry (TSP/MS/MS) of the [M + H]+ ions provided fragment ions characteristic of these metabolites. In addition, TSP mass spectrometry and TSP/MS/MS analysis of ring-hydroxylated N-desmethyldoxylamine, N-desmethylpyrilamine and O-dealkylated pyrilamine is also reported. A fragmentation pathway for analysis by MS/MS of pyrilamine and its metabolites is also proposed. The results demonstrate the utility of TSP/MS for biologically derived metabolites of pyrilamine and doxylamine.

Direct analysis of rat bile for acetaminophen and two of its conjugated metabolites via thermospray liquid chromatography/mass spectrometry.

Bile from rats treated with acetaminophen was analyzed by direct injection onto a thermospray liquid chromatography/mass spectrometry (LC/MS) system. Two conjugated metabolites of acetaminophen were separated by the high-pressure liquid chromatographic system and analyzed by mass spectrometry. The conjugates were identified as the glutathione-acetaminophen conjugate and the glucuronide-acetaminophen conjugate by comparison of the chromatographic retention times and the mass spectra to that of the synthetic standards. No evidence of acetaminophen metabolites was observed when bile samples were subjected to direct analysis by fast atom bombardment mass spectrometry.

Identification of two glucuronide metabolites of doxylamine via thermospray/mass spectrometry and thermospray/mass spectrometry/mass spectrometry.

Analysis of a high-pressure liquid chromatography fraction containing two urinary glucuronide metabolites of doxylamine by thermospray mass spectrometry (TSP/MS) provided [MH]+ ions for each metabolite. TSP/MS/MS of the [MH]+ ions provided a fragment ion characteristic of these metabolites. The results demonstrate the utility of TSP/MS analysis for biologically derived glucuronide metabolites.

Thermospray LC/MS/MS analysis of wastewater for disperse azo dyes.

Primary effluent from a municipal wastewater treatment plant was used as the feed in bench scale activated sludge systems. These systems were spiked with disperse azo dyes at 1 mg 1-1 and 5 mg 1-1 levels and were sampled at various points in the process. Samples were analysed by high performance liquid chromatography with UV = visible detection and by thermospray ionization MS and tandem mass spectrometry (MS/MS) using direct injection or via column chromatography. The tandem mass spectrometry techniques were used both for method development purposes and for the specificity and extra information these techniques can provide. The investigation of the fate of disperse azo dyes in the activated sludge process was a major feature of this study. Major degradation products have been identified by tandem mass spectrometry analyses of these wastewaters. Precision and accuracy data generated by the thermospray tandem mass spectrometry technique are compared to those derived from the high performance liquid chromatography/UV-visible method.