MEASUREMENT OF HIGH-MOLECULAR-WEIGHT POLYCYCLIC AROMATIC-HYDROCARBONSIN SOILS BY PARTICLE-BEAM HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY MASS

Polycyclic aromatic hydrocarbons (PAHs) comprise a class of potentiall y hazardous compounds of concern to the U.S. EPA. The application of p article-beam (PB) liquid chromatography-mass spectrometry (LC-MS) to t he measurement of high-molecular-weight PAHs was investigated. Instrum ent performance was evaluated for 16 PAHs in the molecular weight rang e 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 instrume nt detection limits, as measured by selected ion monitoring on the sin gly charged molecular ion of each PAH, were found to be 0.15-0.60 ng f or PAHs with molecular weights up to 352 u and 2-4 ng for PAHs with mo lecular weights greater than 352 u. Instrument response was generally linear for PAHs with molecular weights 300-352 u and generally nonline ar 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 distr ibution ratio of the singly charged molecular ion to the doubly charge d molecular ion, dependent on molecular weight, ion source temperature , and concentration. Analysis by PB LC-MS was applied to extracts of P AH-spiked soil and a PAH-contaminated soil from the Pacific Northwest. Target analyte concentrations in the PAH-contaminated soil ranged fro m 0.85 to 84 mu g/g. Quantitative estimates for nontarget PAHs also we re determined. Analysis of a second soil extract from a hazardous wast e site in the northeast part of the United States displayed isomeric p atterns of high-molecular-weight PAHs similar to those of the Pacific Northwest extract.