Market basket samples representative of food from six Canadian cities were surveyed from 1992 to 1996. Fifty composites of fatty foods, prepared for consumption were analysed for 40 PCB congeners by gas chromatography-mass spectrometry. Fish and butter contained the highest total PCB concentrations, while milk and infant foods contained the lowest. The dairy and meat composites were major contributors to the total PCB intake of 5.7 ng/kg/day, and to the TEQ (2,3,7,8-tetrachloro-p-dibenzodioxin equivalent) intake of 0.11 pg/kg/day. The pattern of congeners was similar for the different food groups with the exception of fish, which contained less tri- and tetra-chlorinated biphenyls and more of the hexachlorinated congener No. 153.
The technique of immunochemical analysis, including the principles involved, is described and the various types of assay are discussed. Application of these methods to the analysis of foods for residues of pesticides, contaminants, drug residues, and natural constituents is reviewed. Compared with conventional methods, immunoassays offer similar detection limits and greatly simplified sample preparation procedures.
A radioimmunoassay was developed capable of determining Aroclor 1260 in milk at levels of from 20 to 80 ppb and in blood from 2 to 16 ppb. The values obtained by radioimmunoassay correlate well with those determined by gas-liquid chromatography (r2 = 0.96 for milk and 0.99 for blood) but were lower. Antiserum was produced in rabbits and was specific for 2,2',4,4',5,5'-hexachlorobiphenyl. It cross-reacted with congeners and isomers in Aroclor 1254 and 1260 to the extent that a 20% decrease in binding was observed with 0.1 ng of either mixture. The method requires preliminary cleanup of the extract on alumina and utilizes 25% dimethyl sulfoxide in the assay medium to promote solubilization of the substrates.
Enzyme-linked immunosorbent assays were developed for benomyl as its decomposition product, methyl 2-benzimidazoIe carbamate, and thiabendazole in foods. Immunogens consisting of human serum albumin coupled to 2-succinamidobenzimidazole or 2-{2'-succinamido- 4'-thiazolyl)benzimidazole were used in rabbits to raise antisera that were specific for the respective fungicides. Lower limits of quantitation of 0.35 ppm for benomyl and 0.03 ppm for thiabendazole were established without cleanup of the ethyl acetate extract. Recoveries of benomyl from 3 crops spiked at 0.5 to 10 ppm averaged 89% (range 73-109%) and of thiabendazole from 5 crops spiked at 0.1 to 2.0 ppm were 93% (range 81-105%).
Fillets from 11 species of commercial fish from the Great Lakes were analyzed for residues of 39 polychlorinated biphenyl (PCB) congeners and 24 other organochlorine compounds. Eel and trout contained the highest amount of PCB (753 and 633 ppb wet weight, respectively) and other organochlorines (607 and 1404 ppb, respectively); perch and carp contained the lowest residues. The pentaand hexachlorinated PCBs were the major congeners in all species except whitefish, in which the tetrachlorinated congeners predominated. Toxaphene was the most abundant organochlorine pesticide in trout; p,p′ -DDE was the major component of this class in eel. Residue concentrations in commercial carp were compared with residues present in carp from a fishery closed to commercial operation. Although both PCB and organochlorine pesticide levels in carp were among the lowest for all commercial fish samples, levels from the contaminated area were among the highest.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.