Cleanup and Screening of Citrus Extracts for Residues of Benzo(a)pyrene and Two Other Polynuclear Hydrocarbons
Abstract A method has been developed for the cleanup and screening of extracts from citrus fruit for residues of benzo(a)pyrene, 3-methylcholanthrene, and dibenz(a,h) anthracene. Whole fruits were stripped with pentane, the pentane solution was partitioned with dimethyl sulfoxide, the extract was adsorbed on a magnesia column, and the residue from the eluate was chromatographed on thin layer plates beside spots of standard polynuclear hydrocarbons. The addition of 4.1 μg of either benzo(a)-pyrene or 3-methylcholanthrene to the surface of individual fruits was detected, after cleanup, in extracts stripped from samples of 10–15 oranges or 15–20 lemons. Dibenz-(a,h) anthracene added at levels of 0.1 fig per fruit was detected in only occasional samples. With this procedure, no residues of benzo(a)pyrene, 3-methylcholanthrene, or dibenz(a,h) anthracene were detected in more than 40 paired samples of nonwaxed and commercially waxed citrus fruits. With the proposed cleanup procedures, recoveries of the polynuclear hydrocarbons ranged from 50 to 80% as determined by ultraviolet spectral analysis.