| Ambient particulate matter (PM) is of concern to regulatory agencies due to its adverse impacts on public health. A significant contributor to ambient PM is diesel exhaust (as diesel particulate matter, DPM). Current methods for accurately quantifying ambient exposures to DPM are inadequate, as they employ markers that are not well-suited as specific markers for diesel exhaust or because they lack the selectivity and sensitivity to quantify the specific markers at ambient levels. To address this issue, a 2D-HPLC-MS/MS method was developed. This method exhibited novel sensitivity and selectivity for 1-nitropyrene (1NP), a specific molecular marker for diesel exhaust; in addition, this method was used to monitor two additional nitro-PAH species, 2-nitrofluoranthene and 2-nitropyrene, which are formed exclusively via secondary atmospheric reactions. This method was applied to four sets of filter samples from three different locations which were expected to represent three different classes of exposure to diesel exhaust. These locations were: Trujillo, Peru (high exposure); Shenyang, China (medium exposure); and Seattle, Washington (low exposure). The results of these analyses were congruent with what was anticipated due to existing knowledge of environmental regulations in these areas. In addition, urine samples were analyzed for urinary metabolites of 1NP in two of these groups; the Shenyang group and a Seattle group. Differences in the concentrations of 1NP metabolites were observed, although these differences were not of the same magnitude as the differences in 1NP exposures. The results of the filter analyses indicate that the 2D-HPLC-MS/MS method developed has adequate selectivity and sensitivity to detect trace levels of environmentally relevant nitro-PAH species in ambient PM samples. The results of the urine analysis indicate that while the 1NP metabolites detected may not be adequate as biomarkers of acute exposure to diesel exhaust, they may have potential as biomarkers of chronic exposure to diesel exhaust. |
