Collections > Master's Papers > Gillings School of Public Health > Development of a Procedure for Sampling, Fractionation and HPLC Analysis of Nitrated Polycyclic Aromatic Hydrocarbons in Air
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A procedure has been developed for sampling, fractionation and HPLC analysis of carcinogenic nitrated polycyclic aromatic hydrocarbons (nitro-PAH) in air. A high volume sampling system was selected consisting of a Teflon coated glass fiber filter and two polyurethane foam (PUF) plugs in series downstream from the filter. Teflon coated filters were chosen because of their low catalytic potential for artifact formation of nitro-PAH during sampling. PUF was used over XAD-2 resin for sampling volatilized nitro-PAH because of better blank values and extraction efficiencies. Recoveries of simulated sampling experiments (nitro-PAH added on filters were volatilized by operating the sampling pumps) were in the range of 73.6 - 93.8 %. Fractionations of crude sample extracts were performed using a normal phase preparative HPLC column and an 83 minute solvent program that controlled the proportions of n-hexane, methylene chloride and acetonitrile as constituents of the mobile phase. The selected method consisted of an HPLC separation on a reversed phase column (Supelcosil LC-PAH (5 micron)) using a mixture of methanol/water (80/20) as the mobile phase. After separation the nitro-PAH were reduced on-line to the corresponding amino-PAH using a heated catalytic reducer column containing a platinum-rhodium three-way automotive catalyst. A fluorescence detector was used to quantify the amino-PAH produced. The nine nitro-PAH studied in this project could be analysed in chromatograms of 17 minutes length and with detection limits ranging from 7.6 - 90 pg/10 microliter injection. The identity between sample and standard compounds could be tested by comparing peak height changes that occured when non-optimal wavelengths for the emitted fluorescence light were used for detection instead of the optimal wavelenths. In this way, 1-nitropyrene was confirmed in a filter sample from a conveyor station of a carbon plant.