Determination of trace residues of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs and PCDFs) in various matrixes is carried out by a limited number of laboratories in the United States, Canada, and other countries. Current methods for analysis of foods and biological tissues include a combination of preparation, extraction, cleanup, isolation, determination, and identity confirmation procedures. Soxhlet, liquid/liquid, solid-phase, and column extraction procedures are used as well as treatment with acid or base before solvent extraction. Cleanup and isolation steps include sulfuric acid partitioning; adsorption chromatography on Florisil, silica gel, or alumina; gel permeation chromatography; multi-stage column chromatography on sulfuric acid silica and alkali silica; carbon column chromatography; and liquid chromatography fractionation with size exclusion, normal-phase, and reverse-phase columns. Activated carbon and multistage chromatographic columns are widely used in cleanup schemes. Isomer-specific identification and quantitation of PCDD and PCDF congeners at parts-per-trillion levels or lower are carried out by high resolution (capillary) gas chromatography (HRGC) and multiple ion detection mass spectrometry. In addition to chemical methods, bioassay procedures have been recommended (e.g., use of monoclonal antibodies, for immunoassay determination of PCDDs and PCDFs).

Animals↗

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Determination of the iodine value of oils and fats: summary of collaborative study.

Two collaborative studies were conducted using the Wijs method for determining the iodine value in a wide range of vegetable and animal oils and fats. The results obtained when using carbon tetrachloride were compared to those obtained when using a substitute solvent mixture of cyclohexane and glacial acetic acid. The values reported for the iodine values indicate that the cyclohexane and acetic acid mixture can be used in place of carbon tetrachloride without loss of precision. The method has been adopted first action by AOAC INTERNATIONAL as an IUPAC/AOCS/AOAC method.

Acetates↗

PubMedDate not supplied

Gas chromatographic determination of mono- and diglycerides in fats and oils: summary of collaborative study.

A collaborative study was conducted on a capillary gas chromatographic method for the determination of mono- and diglycerides in fats and oils. Other components of fats and oils such as glycerol, fatty acids, and sterols may be analyzed by this method. Six materials used in the study consisted of 2 commercial mono- and diglyceride emulsifiers, 2 synthetic compositions with known amounts of mono- and diglycerides in the presence of an excess of triglycerides, and 2 refined sunflower oils spiked with mono- and diglycerides. Eight laboratories participated in the study. On the basis of the collaborative study results, the method has been adopted first action by AOAC INTERNATIONAL as an IU-PAC/AOCS/AOAC method.

Chromatography, Gas↗

PubMedDate not supplied

Direct graphite furnace-atomic absorption method for determination of lead in edible oils and fats: summary of collaborative study.

The IUPAC Commission on Oils, Fats, and Derivatives undertook development of a method and collaborative study for the determination of lead in oils and fats by direct graphite furnace-atomic absorption spectrophotometric method. Various types of graphite furnaces were used with or without platform. Twenty-three collaborators from 12 countries participated in the study. The materials tested were edible oils (soybean oil) and fats (cocoa butter) containing lead at 3 concentration levels (low, medium, and high). Each level was represented by 2 batches provided in duplicate (blind coded), so that each collaborator received a total of 24 test samples. Collaborators were instructed to analyze each in duplicate and report both results. Twenty collaborators returned the results of the study. After data from laboratories that did not follow the instructions were excluded, only 16 sets of data were evaluated statistically. The method for determination of lead in oils and fats by direct graphite furnace-atomic absorption spectrophotometry has been adopted first action by AOAC INTERNATIONAL as an IUPAC-AOCS-AOAC method.

Fats↗

PubMedDate not supplied

Liquid chromatographic method for determination of triglycerides in vegetable oils in terms of their partition numbers: summary of collaborative study.

The IUPAC Commission on Oils, Fats and Derivatives undertook development of a method and collaborative study for the determination of triglycerides in vegetable oils by liquid chromatography. Three collaborative studies were conducted from 1985 to 1987. Refinements were made in the method after the first collaborative study, and the second and third collaborative studies demonstrated that the method produces acceptable results. Materials studied were soybean oil, almond oil, sunflower oil, olive oil, rapeseed oil, and blends of palm and sunflower oils, and almond and sunflower oils. Six test samples were analyzed by 18 laboratories from 11 countries in the second study; 4 test samples were analyzed by 16 laboratories from 12 countries in the third study. The method for determination of triglycerides (by partition numbers) in vegetable oils by liquid chromatography was adopted first action by AOAC INTERNATIONAL as an IUPAC-AOCS-AOAC method.

Chromatography, Liquid↗

PubMedDate not supplied

Gel-permeation liquid chromatographic method for determination of polymerized triglycerides in oils and fats: summary of collaborative study.

The IUPAC Commission on Oils, Fats and Derivatives undertook development of a method and collaborative study for determination of polymerized triglycerides in oils and fats. Two collaborative studies were carried out by IUPAC in 1985 and 1986. Both studies consisted of 4 materials, including animal fat, frying oil with average content of polymers, and blends of frying oil containing varying amounts of polymers. Thirteen and 17 laboratories were included in the first and second IUPAC collaborative studies, respectively. Another collaborative study conducted by inspectorate for Health Protection, Food Inspection Service, The Netherlands, included 13 laboratories. Six heat-processed fat samples (3 pairs of split samples) containing 14-28% (w/w) of polymerized triglycerides were studied. The method was adopted by AOAC INTERNATIONAL as an IUPAC-AOCS-AOAC method.

Chromatography, Gel↗

PubMedDate not supplied

TCDD residues in fish and shellfish from U.S. waterways.

TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) in the edible portion of fish and shellfish from various U.S. waterways has been monitored since 1979. Analytical results for the period 1979-1994 are reported. Extracts obtained after column chromatographic and liquid chromatographic cleanup were examined by electron capture detection-gas chromatography (GC), and final quantitation and confirmation were performed by GC/mass spectrometry with multiple ion detection. Analyses of 1623 test samples indicated that TCDD residues in fish and shellfish were not widespread but rather were localized in areas near waste sites, chlorophenol manufacturers, and pulp and paper mills. Analytical results indicated that levels in aquatic species from these sites have been declining steadily. No TCDD (limit of detection and confirmation, 1-2 ppt) has been found in recent years in aquatic species from most Atlantic, Pacific, and Gulf of Mexico sites and Great Lakes other than Lake Ontario and Saginaw Bay (Lake Huron).

Animals↗