Determination of Polycyclic Aromatic Hydrocarbons in Sediment by Liquid Chromatography-Atmospheric Pressure Photoionization–Mass Spectrometry

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants whose carcinogenicity and mutagenicity have been extensively studied. 1They are byproducts of the incomplete combustion of fuels and wood, and persist in the environment. 2 The concentrations of PAHs in the atmosphere are regarded as indicators of air pollution, and the historical trends of PAHs recorded in the sediment core from a reservoir should reflect the changes in the atmospheric pollution around the reservoir. 3 In order to evaluate the atmospheric environment at the sampling point and the historical trend of the PAH risk in the atmospheric environment, it is very important to establish an analytical method for PAHs in sediment samples.Tsuji et al. reported a method for the determination of PAHs in sediment using ultrasonic extraction of the PAHs and a cleanup solid-phase extraction procedure, followed by LC/fluorescence detector. 4 However, it is difficult to detect PAHs which have a poor fluorescence, such as indeno [1,2,3-c,d]pyrene, using the fluorescence detector.The LC/MS method would supply more useful information for the analysis of PAHs because of the relatively high specificity of the MS detector compared to the UV or fluorescence detector. However, very few examples are known based on the detection of PAHs by LC/MS using several commercially available interfaces, including thermospray, 5 liquid ionization 6 and atmospheric pressure chemical ionization.7 Furthermore, there were only a few reports about the detection of PAHs using electrospray as the interface due to difficulty of ionizing low polar compounds. 8,9 Recently, Bruins et al. introduced the dopant assisted atmospheric pressure photoionization (APPI) technique, which was a novel LC/MS ionization and can achieve the ionization of low polar compounds, such as PAHs. 10,11 However, there are few reports on the application of this technique to environmental analysis. 12 In this report, we present a method for the determination of PAHs in sediment samples by the ultrasonic extraction of PAHs and a clean-up solid-phase extraction procedure followed by LC/APPI/MS. Experimental MaterialsThe following 12 PAHs were detected and determined in this study: phenanthrene (Phe), anthracene (An), fluoranthene (Flu), pyrene (Py), benzo(a)anthracene (B(a)A), chrysene (Chr), benzo(b)fluoranthene (B(b)F), benzo(k)fluoranthene (B(k)F), benzo(a)pyrene (B(a)P), benzo(e)pyrene (B(e)P), benzo(ghi)perylene (BghiP) and indeno [1,2,3-c,d]pyrene (IP). These compounds were obtained from SUPELCO (Tokyo, Japan). All solvents were of HPLC grade, while the other chemicals were of analytical-reagent grade. Benzo(a)pyrene-d12 was used as the internal standard, and purchased from Hayashi Pure Chemical Industries (Osaka, Japan). Ammonium acetate and acetic acid were obtained from Wako Pure Chemical (Osaka, Japan). Ultra-pure water was produced by a Milli-Q system (Millipore, Bedford, USA). A sediment sample was obtained from Nagaike, which is a reservoir located in the southern part of Osaka C...

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