Chemical Residues, Determination of Perchloroethylene in Strawberries

Abstract A gas chromatographic (GC) method is described for the determination of 22 fumigant and industrial chemical residues in a variety of foods. The fumigants and industrial chemicals determined are methyl bromide, methylene chloride, carbon disulfide, chloroform, 1,1-dichloroethane, ethylene dichloride, methyl chloroform, carbon tetrachloride, methylene bromide, propylene dichloride, 2,3-dichloropropene, trichloroethylene, 1,3-dichloropropylene, 1,1,2-trichloroethane, chloropicrin, ethylene dibromide, tetrachloroethylene, propylene dibromide, l,l,2,2-tetrachloroethane,j»-dichlorobenzene, o-dichlorobenzene, and l,2-dibromo-3-chloropropane. Except for the latter three, the fumigants are determined at 90°C on 3.6 m 20% loaded OV-101 columns with electron-capture and Hall-electroconductivity detectors. The other 3 compounds (o-dichlorobenzene, p-dichlorobenzene, and l,2-dibromo-3-chloropropane), which elute beyond 30 min on the above columns, are determined at 90°C on 1.8 m 5% loaded OV-101 columns with the same detectors. The ng/g-level fortifications have an overall mean analyte recovery of 70% and a coefficient of variation of 40%. The variety of foods examined includes both fatty and nonfatty food types (e.g., off-the-shelf cooked and uncooked grain-based items, dairy products, fresh and canned fruits and vegetables, and meats). Samples are extracted and cleaned up according to fat content and food type. Samples containing less than 71% fat are extracted by using an aqueous: nonaqueous shakeout (20% acetone solution under isooctane). Most extracts (isooctanes) are analyzed directly. Extracts from samples containing from 21 to 70% fat (e.g., ground beef, pecans, and corn chips) are cleaned up further on micro-Florisil columns to remove excess fat. A few other samples containing more than 71% fat or oil (e.g., butter, salad dressing, and vegetable oil) are diluted directly in isooctane and, depending on the degree of dilution, can be cleaned up further on micro-Florisil columns. Also, clear beverages (e.g., soda and tea) are extracted directly with isooctane. These extraction and cleanup techniques were tested on 231 different table-ready foods. Three-hundred incurred residues of 10 different fumigants were found in 138 items examined; 93 items had no detectable residues. The main advantage of the method is rapid semiquantitative determination of multiple fumigants from all food types.

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Gas-Liquid Chromatographic Determination of Chlordene Epoxide in Catfish

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/61.1.1 ◽

1978 ◽

Vol 61 (1) ◽

pp. 01-04

Author(s):

Gabriel D Castillo ◽

Marshall T Jeffus ◽

Charles T Kenner

Keyword(s):

Mass Spectra ◽

Chromatographic Determination ◽

Gas Liquid Chromatography ◽

Edible Portion ◽

The Third ◽

Chemical Residues ◽

Fish Samples ◽

Liquid Chromatographic Determination ◽

Liquid Chromatographic

Abstract Chlordene epoxide was detected in the range of 0.04 to 0.27 ppm in the edible portion of 3 catfish samples during the analysis of 36 fish samples by electron capture gas-liquid chromatography (GLC) for pesticide and industrial chemical residues. Two of these catfish samples were from suppliers in Louisiana and the third was from a Texas supplier. Chlordene was also present; the amount of chlordene epoxide in the 3 samples averaged 46% of the amount of chlordene present. The epoxide was identified by comparison of the mass spectra and the CLC retention times of the samples with reference material prepared in this laboratory.

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