[Method for identifying and determining polycyclic aromatic hydrocarbons in foods, soil and drinking water].

A method is described for identifying and determining polycyclic aromatic hydrocarbons in foods, soil and drinking water that, owing to the combination of extractive, chromatographic and spectrophotometric techniques, permits to detect 0,01 microgram of bezo(a)pyrene/kg in the presence of other polycyclic aromatic hydrocarbons. The preparation, pretreatment and concentration of the samples depend upon their nature. The isolation and separation of the polycyclic aromatic hydrocarbons are achieved with the aid of two consecutive thin-layer chromatographic systems, silica gel and acetylated cellulose. The subsequent identification and determination are based on the ulta-violet spectra (limit of detection, almost 0,5 microgram/ml) and, in the nanogram range, on the in situ fluorescence spectral analysis (limit of detection, 0,005 microgram of benzo(a)pyrene/spot). Fluorescence excitation and emission spectra obtained directly from the acetylated cellulose plate permit not only the reliable identification but also the determination of the polycyclic aromatic hycrocarbons; fluorescence transfer loci obtained under various conditions, the simultaneous determination. Depending upon the kinds of sample material, the recovery values range from 75 to 99.6% with a variation coefficient between 10.3 and 22.1%. Furthermore, a limiting value method is presented that permits to take yes-no decisions, by means of thin-layer chromatographic screening without using complicated measuring techniques, indicating whether or not the respective sample complies with the benzo(a)pyrene standard.