An optimized sample preparation and analysis method for the determination of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in the atmospheric bulk deposition samples.

A method based on solid phase extraction (SPE), gas chromatography tandem mass spectrometry (GC-MS/MS) and gas chromatography with electron capture detector (GC-ECD) was developed for the determination of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in atmospheric deposition samples. Six indicator PCB congeners were analysed by GC-ECD equipped with two micro electron-capture detectors and two gas chromatographic columns, while 12 PAH compounds were analysed by GC-MS/MS. Solid phase extraction on silica sorbent proved suitable for accumulation of PAHs and PCBs from deposited matters. The extraction procedure was based by passing the whole sample volume through a silica cartridge with dichloromethane and n-hexane as the eluting solvents. Two different performances of a bulk collector were compared. The method was validated using field total deposited samples collected monthly over a year by bulk method at an urban background station in Zagreb, Croatia. The levels and occurrence of PCBs corresponded to global environmental pollution, with the deposition rates of ∑6PCBs between 6 - 28 ng m-2 d-1. The deposition rates of ∑12PAHs varied between 132 and 714 ng m-2 d-1 during the warm period, whereas it achieved a significantly higher range of 171 to 1069 ng m-2 d-1 in the cold period.