Modelling of additive diffusion in polyolefins.

A semi-empirical model has been developed for additive diffusion in polymers. The model estimates apparent diffusion coefficients of an additive migrating through polyolefin polymers into a fatty food simulant for a range of temperatures between the glass transition and melting temperatures of the polymer. This diffusion model has been applied to several additive/polyolefin systems to determine its validity and limitations.

Determination of migrants in and migration from nylon food packaging.

A method was developed to determine the amount of residual oligomers in nylon food packaging. In addition, a method was developed to measure oligomers that migrate to a food-stimulating liquid (oil) during oven cooking conditions. It was found that the total amount of nylon 6/66 oligomers that migrated from an oven baking bag to oil after heating for 30 min at 176 degrees C was 15.5 micrograms/g (ppm) or 11.9 micrograms/cm2, which represented 43% of the total amount of oligomers present in the packaging material.

Effects of temperature and mixing on polymer adjuvant migration to corn oil and water.

The effect of mixing on the migration of Irganox 1010 antioxidant from polypropylene and high-density polyethylene to water and corn oil was compared at 77, 100, and 135 degrees C. Irganox 1010 migration to water is enhanced almost five-fold by mixing at 77 degrees C, whereas at 135 degrees C, mixing has only a nominal effect on migration. Irganox 1010 migration to corn oil is virtually unaffected by mixing at the temperatures studied. Migration data indicate a similar trend for Irganox 1076.

Survey of trihalomethanes and other volatile chemical contaminants in processed foods by purge-and-trap capillary gas chromatography with mass selective detection.

A limited number of soft drinks, juices, beers, and waters from processed vegetables were analyzed for trihalomethanes (THMs), benzene, and toluene by a modified Environmental Protection Agency (EPA) Method 524.2. The THMs, which include chloroform, bromodichloromethane, dibromochloromethane, and bromoform, are reaction by-products of water disinfection by chlorination. EPA Method 524.2 is a purge-and-trap capillary gas chromatographic method based on mass spectrometric detection which identifies and simultaneously measures purgeable volatile organic compounds in drinking water. Chloroform was present at concentrations ranging from none detected to 94 ng/g in the 44 foods analyzed. Bromoform was not found in any of the products at a detection limit of 0.1 ng/g. Residue levels of the other THMs ranged from none detected to highs of 12 and 2 ng/g for bromodichloromethane and dibromochloromethane, respectively. Benzene residues were typically < 5 ng/g, except for 7 and 9 ng/g in 2 foods. Toluene residues were typically < or = 3 ng/g except for 23, 29, and 75 ng/g in 3 canned foods.

Survey of benzene in foods by using headspace concentration techniques and capillary gas chromatography.

Recently, the combination of sodium or potassium benzoate with ascorbic acid was shown to produce low levels (ng/g) of benzene in fruit-flavored soft drinks. The presence of benzene also was reported in butter, eggs, meat, and certain fruits; levels of these findings ranged from 0.5 ng/g in butter to 500-1900 ng/g in eggs. Because benzoates are widely used as food preservatives, a limited survey of other foods containing added benzoate salts was conducted to investigate the potential for benzene formation. Selected foods that did not contain added benzoates but were previously reported to contain benzene were analyzed for comparison. More than 50 foods were analyzed by purge-and-trap or static headspace concentration and capillary gas chromatography. Benzene was quantitated by using the method of standard additions, and its identity was confirmed by mass selective detection. Results of this limited survey show that foods without added benzoates (including eggs) contained benzene at levels equal to or less than 2 ng/g. Slightly higher levels were present in some foods and beverages containing both ascorbic acid and sodium benzoate.

Determination of volatile chemicals released from microwave-heat-susceptor food packaging.

Microwave heat susceptors that convert electromagnetic energy to heat attain high temperatures that make it possible to cook some foods to golden crispness in a microwave oven. Susceptors are typically packaged with foods intended for microwave use, e.g., waffles, pizzas, and french fries. The high temperatures > 302 degrees F used to cook some foods release trace levels of volatile chemicals from metalized polyester film, adhesive, and paper packaging materials; these volatile chemicals may be absorbed by the food. We simulated microwave susceptor cooking conditions and developed protocols by using headspace concentration capillary gas chromatography and mass spectrometry to identify volatile chemicals released from heated susceptors. We purchased a limited, cross-sectional sample of local retail microwave food products packaged with susceptors and used our protocol to analyze 10 different susceptor products. Although more than 140 unique chromatographic peaks were tabulated, only 44 volatile chemicals were identified, including 1,1,1-trichloroethane, benzene, and 2-(2-butoxyethoxy)ethanol, which were derived primarily from the paper and adhesive susceptor components. No one susceptor contained all the identified substances. The standard additions technique was the preferred method for quantitation. Trichloroethane and 2-(2-butoxyethoxy)ethanol were present in several products at 75-122 micrograms/in.2 of susceptor surface area. Benzene was found in 3 susceptors at < or = 0.22 microgram/in.2 levels. Examination indicates that adhesives used in more recent susceptor products were reformulated to remove even this trace level of benzene.

Determination of benzene in polypropylene food-packaging materials and food-contact paraffin waxes.

An analytical procedure was developed for determination of benzene in polypropylene food packaging and was adapted for determination of benzene in commercial paraffin waxes intended for food-contact use. The polymer was dissolved in hexadecane at 150 degrees C. The wax was melted in an 80 degrees C oven. A simple helium-sparging apparatus was used to remove the volatile chemical from the polymer or wax. The contaminant was collected in methanol, distilled water was added, and the resulting solution was analyzed by headspace gas chromatography. The instrument was equipped with a 30 m fused silica open tubular capillary column and a photoionization detector. Average recoveries of benzene from polymer and paraffin wax at low parts-per-billion concentrations were 63 and 70%, respectively. Limits of detection and quantitation for analysis of polypropylene were 8 and 17 ppb, respectively; the limit of quantitation for analysis of paraffin wax was 2 ppb. In several commercial polypropylene products examined, benzene levels ranged from none detected to 426 ppb. In 3 commercial waxes examined, concentrations of 16-73 ppb benzene were determined. The presence of benzene was confirmed by gas chromatography/mass spectrometry.

Migration into food of polyethylene terephthalate (PET) cyclic oligomers from PET microwave susceptor packaging.

A quantitative method has been developed to measure the migration of polyethylene terephthalate (PET) cyclic oligomers from aluminized PET susceptor film-type food packaging into several food types. Microwaveable French fries, popcorn, fish sticks, waffles and pizza sold in susceptor-type packaging were purchased in local markets, cooked according to package instructions and analysed for PET oligomers. Appropriate food blanks were cooked in glass containers. Quantities of PET oligomers found in the foods ranged from less than 0.012 micrograms/g to approximately 7 micrograms/g.

Evaluation of polyethylene terephthalate cyclic trimer migration from microwave food packaging using temperature-time profiles.

The polymer polyethylene terephthalate (PET) is widely used for packaging food that will be heated or cooked in the PET container. A procedure was developed to predict the potential of PET to migrate from the container into the food. Migration experiments using crystallized polyethylene terephthalate (CPET) and corn oil were performed at 115, 146 and 176 degrees C. From these experiments diffusion coefficients were calculated for the cyclic trimer in PET. By using an Arrhenius plot to obtain the diffusion coefficient and a temperature versus time plot of a microwave susceptor-heated CPET tray, it was possible to predict migration of the cyclic trimer into corn oil under microwave conditions. Predicted values were in good agreement with measured results.

Quantitative multiresidue analyses for volatile organics in water and milk, using a fused silica open-tubular wide-bore capillary column and automated headspace gas chromatography.

A modified multiresidue capillary gas chromatographic (GC) procedure has been developed using automated headspace sampling and a wide-bore fused silica open-tubular (FSOT) capillary column for the determination of volatiles in water and milk. Compounds are quantitated by the method of standard additions. An IBM System 9000 computer with the CAPMC3 chromatographic applications package and a BASIC linear regression program are used for data reduction. Data are presented for solutions prepared by fortifying water and milk with volatile solvents such as acetone, methyl ethyl ketone, benzene, methylene chloride, and chloroform, which are commonly used in the manufacture of packaging materials and adhesives. The wide-bore FSOT capillary columns showed dramatically improved detection for certain compounds, compared with normal-bore capillary GC columns. Data presented for various chemicals demonstrate the improved limits of detection from the use of automated headspace gas chromatography with wide-bore capillary columns and flame ionization detection.

A multiresidue approach to the identification of food packaging-derived volatiles in foods and containers.

A rapid approach to the tentative identification of food packaging-derived volatile residues in foods and containers by use of headspace sampling, capillary gas chromatography, and a computer data search program is described. Headspace vapors of samples are analyzed on Ov-101 and Carbowax 20M columns. Peak retention time data of a sample on both columns are compared with those of common packaging raw materials, by-products, and processing agents maintained in a standard reference file. A list of possible identities based on the chromatographic peaks is compiled and printed out. Additional supporting data, such as relative peak response on each column, are examined to make a tentative identification. Other methods must be employed to confirm these identifications.

Container-derived contamination of maple sirup with methyl methacrylate, toluene, and styrene as determined by headspace gas-liquid chromatography.

Samples of maple sirup and associated plastic packaging were examined for the presence of methyl methacrylate, toluene, and styrene by a head space gas chromatographic procedure. The volatile components common to the sirup and the plastic container were identified by gas chromatography-mass spectrometry. The quantities of these contaminants in the sirup were determined at ppb levels by the standard additions technique and repetitive headspace analysis.

Identification of cholesterol as a possible interference in the analysis of fish tissue for industrial chemical residues.

The presence of cholesterol in cleaned up fish tissue extracts has been established by gas-liquid chromatography and confirmed by mass spectrometry. It was found both in extracts cleaned up by gel permeation chromatography and in those extracts prepared by the AOAC method for nonfatty foods. It is not normally observed in routine residue analyses because selective gas chromatographic detectors such as electron capture are commonly used.

Fluorescence and phosphorescence characteristics of anticoagulants: A new approach to direct measurement of drugs in whole blood.

Fluorimetric and phosphorimetric excitation and emission peaks and limiting detectable concentrations and phosphorimetric decay times are given for warfarin, dicumarol, diphenandione, phenindione and tromexan. Known concentrations of warfarin, a highly fluorescent compound, and dicumarol, a highly phosphorescent compound, are directly measured in the complex biochemical system of whole blood. Excellent recoveries of warfarin and dicumarol in the concentration range of 0.1 to 10 mg% in whole blood were achieved.