Recommended Method for the Gas Chromatographic Profile Analysis of Polycyclic Aromatic Hydrocarbons in Smoked Food

Results are reported of a collaborative study on the determination of polycyclic aromatic hydrocarbons (PAH) including benz(a)anthracene, chrysene, benzofluoranthenes (b++k), benzo(a)pyrene, benzo(e)pyrene, and indeno(l,2,3-cd)pyrene in smoked meat. After calibration of the instrument with a standard solution, four samples of smoked meat (two of each were identical samples, respectively) were analysed. Variation coefficients for the above PAH were found to be 19.5-57.5 % with the exception of indeno(l,2,3-cd)pyrene for which a coefficient of 105.5126.9 % was found due to an external impurity which interferes with this PAH in GC. INTRODUCTION Although in many environmental studies only benzo(a)pyrene has been regarded as a carcinogenic representative of PAH, it is well-known that other individuals of this class considerably contribute to the total carcinogenicity of various environmental matter (1, 2). As a consequence, a profile analysis is required which allows the simultaneous determination of as many as possible PAH. Due to legislative regulations which restrict the concentration of six selected PAH to 200 or 250 ng/L water, a thin-layer chromatographic determination method has been developed which is widely used for water control (3). Since, however, resolution for additional PAH is poor with this method, for more sophisticated problems gas chromatography is applied. A previously described CC method (L) has been used in an internal collaborative study including 7 laboratories. SCOPEAND FIELD OF APPLICATION The method specifies a procedure for the gas chromatographic profile analysis of PAH (including benz(a)anthracene, chrysene, benzofluoranthenes (b+j+k) , benzo(a)pyrene, benzo(e)pyrene and indeno(l,2,3-cd)pyrene) in smoked meat. It also can be applied to other materials and allows, moreover, the determination of other PAH as well. The enrichment procedure specif ically separates PAH which are gas-chromatographically analysed and quantified by comparison with internal standards. The method has a limit of detection of about 0.3 ng PAH. PRINCIPLE The sample is spiked with two standards (indeno(l,2,3-cd)fluoranthene and benzo(b)chrycene), and grinded in a mincer (meatchopper) and homogenized for 20 sec at room temperature in l,l,2-trichlorotrifluorethane (TCFE) or, alternatively, refluxed for 30 mm with TCFE or cyclohexane. An aliquot of this solution obtained by decanting is extracted with methanol! water (7+3). In case of TCFE extraction, this is removed by distillation and the residue is then dissolved in cyclohexane. The cyclohexane is extracted with a mixture of N,N-dimethylformamide (DMF)/water (9+1). The remaining DMF/water phase is diluted with water and the PAH extracted with cyclohexane. The cyclohexane phase is washed with water and filtered through silica. After cautious evaporation to near dryness the residue is dissolved in isopropanol and separated by chromatography on Sephadex LH 20 by elution with isopropanol into PAH with 2 and 3 rings and a fraction containing PAH with more than 3 rings. After evaporation of the solvent to near dryness the latter fraction is redissolved in toluene (10-20 pL) and analysed by CC using capillary columns. A schematic representation of the procedure is given in Figure 1. MATERIAL All solvents used (cyclohexane, methanol, dimethylformamide, isopropanol (propanol-2), acetone) were of analytical grade and redistilled in carefully cleaned glass vessels before use. Before analyzing a sample a blank test following the entire procedure should be carried out. For column chromatography silica 60 (particle size 0.063-0.200 mm 70-230 mesh ASTM) and Sephadex LH 20 (Pharmacia Fine Chemicals, S-75l0k Uppsala 1, Sweden) were used. The following reference PAH were obtained in a better than 99.0 % purity from the Commission of the European Community, Community Bureau of Reference BCR, Rue de la Loi 200, B-10k9 Brussels, Belgium: fluoranthene, pyrene, benzo(c)phenanthrene, benzo(ghi)fluoranthene, benz(a)anthracene, chrysene, triphenylene, benzo(b)fluoranthene, benzo(j)fluoranthene, benzo(k)fluoranthene, benzo(e)pyrene, benzo(a)pyrene, perylene, indeno(l,2,3-cd)pyrege, benzo(ghi)perylene, anthanthrene, coronene as well as the internal standard indeno(l,2,3cd)fluoranthene and benzo(b)chrysene. A reference solution for the calibration of the CC instrument and for the determination of the CC retention times contained the following PAH: benz(a)anthracene (5.20 ng!pL); chrysene