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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.

Groundwater at or near Superfund sites often contains much organic matter, as indicated by total organic carbon (TOC) measurements. Analyses by standard GC and GC/MS methodology often miss the more polar or nonvolatile of these organic compounds. The identification of the highly polar or ionic compounds may be needed to assess toxicity more reliably, to plan remediation, and to establish the possible source of a waste and the responsible party. This study characterized water samples from two Superfund sites for organic components where routine methods had failed to account for a majority of the TOC. Carboxylic acids, alcohols, and ketones were detected by GC/MS using a new capillary column designed for polar organic compounds. Particle beam LC/MS allowed for identifying several additional compounds. Finally, thermospray LC/MS was shown to be an excellent means of detecting ionic constituents, such as aromatic sulfonic acids, in the water samples.

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