Estimated content percentages of volatile liquids and fat extractables in ready-to-eat foods.

Content percentages of volatile liquids and fat extractables in 340 samples of ready-to-eat foods were determined gravimetrically. Volatile liquids were determined by drying samples in a microwave oven with a self-contained balance; results were printed out automatically. Fat extractables were extracted from the samples with mixed ethers; extracts were dried and weighed manually. The samples, 191 nonfat and 149 fatty (containing ca 2% or more fat) foods, represent about 5000 different food items and include infant and toddler, ethnic, fast, and imported items. Samples were initially prepared for screening of essential and toxic elements and chemical contamination by chopping and mixing into homogenous composites. Content determinations were then made on separate portions from each composite. Content results were put into a database for evaluation. Overall, mean results from both determinations agree with published data for moisture and fat contents of similar food items. Coefficients of variation, however, were lower for determination of volatile liquids than for that of fat extractables.

Evaluation of an automated gel permeation cleanup and evaporation systems for determining pesticide residues in fatty samples.

The AutoVap 600 system, used in conjunction with an automated gel permeation chromatography (GPC) instrument, automatically collects and evaporates the effluent from the GPC column, dissolves the residue in a fixed volume of desired solvent, and quantitatively transfers it to a sealed vial. This system was evaluated and found to automate efficiently the cleanup of butterfat for pesticide residue analysis. Quantitative recoveries were obtained for each of 4 pesticides fortified in butterfat and cleaned up through the system and for 12 pesticide standards in the absence of sample matrix collected through the system. After loading, the system operates unattended and will automatically prepare up to 23 individual fat samples for determination by gas chromatography without additional cleanup.

Gas-liquid chromatographic determination of pentachlorophenol in Mason jar lids and home canned foods.

A method was developed for the determination of pentachlorophenol (PCP) in the seals and enamel of Mason lids. After extraction with acidic CH2Cl2 and methylation, the resulting pentachloroanisole was determined by gas-liquid chromatography (GLC) with electron capture detection (EC). Three of the 9 brands of lids examined contained PCP. Levels were as high as 198 micrograms/lid. Recoverires from fortified samples ranged from 92 to 103%. Six fruits and vegetables were canned by home canning techniques, using lids shown to contain PCP. PCP in these foods was determined by a procedure specifying extraction with acidic CH2Cl2 and gel permeation chromatography cleanup. Extracts were methylated and determined by GLC-EC. PCP was found in all the canned foods. Levels were as high as 16 micrograms/qt. Recoveries from foods fortified with PCP ranged from 85 to 94%. The presence of PCP was confirmed by GLC-mass spectrometric determination of the derivative, pentachloroanisole.

Mass spectrometric identification and gas-liquid chromatographic determination of 2-chloroethyl esters of fatty acids in spices and foods.

The 2-chloroethyl esters of 5 fatty acids have been identified in spice and food samples by gas-liquid chromatography-mass spectrometry (GLC/MS). Twenty-four spice samples were analyzed for the 2-chloroethyl esters of fatty acids by AOAC official multiple residues pesticide procedure using GLC with microcoulometric detection. The esters of capric, lauric, myristic, palmitic, and linoleic acids have been identified at levels up to 1400 ppm. 2-Chloroethyl linoleate was the most abundant ester in all samples. Several foods analyzed by the same procedures showed levels of 2-chloroethyl linoleate as high as 35 ppm. Recoveries from fortified samples ranged from 84 to 98% for the various esters. A method using an acid-catalyzed esterification reaction was developed to rapidly determine the fatty acid content of these spices. GLC analysis with microcoulometric detection was used. Recoveries from fortified samples ranged from 92 to 110%. After 2 spice samples found to be free of 2-chloroethyl esters were fumigated with ethylene oxide, the level of 2-chloroethyl linoleate reached 77 ppm. All levels of 2-chloroethyl esters were confirmed by GLC/MS.