Development of a rapid screening method to determine primary aromatic amines in kitchen utensils using direct analysis in real time mass spectrometry (DART-MS).

Primary aromatic amines (PAAs) are a group of substances with undesirable health effects, that are used in a variety of commercial products. Several recent studies, using a number of screening and confirmatory methods, have reported the migration of PAAs from some kitchen utensils into acetic acid 3% (w/v). Many of these methods require significant sample preparation, therefore the aim of this work was to determine if direct analysis in real time mass spectrometry (DART-MS) could be utilised as a rapid screening tool for the determination of PAAs in kitchen utensils. DART-MS results from direct analysis of the utensil have been compared with results of PAA migration by ultra high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method. The UPLC-MS/MS method had excellent linearity, appropriate sensitivity (LOD ≤ 1.5 µg L(-1); LOQ ≤ 4.5 µg L(-1)), repeatability from 2.4 to 13.2% and acceptable recoveries. DART-MS results were in good agreement with UPLC-MS/MS data, with 100% of non-compliant (PAA positive) samples successfully identified by DART-MS.

Migration of perfluoroalkyl acids from food packaging to food simulants.

A broad range of fluorochemicals is used to impart oil and water barrier properties to paper and paperboard food packaging. Many of the fluorochemicals are applied to paper and paperboard as complex mixtures containing reaction products and by-products and unreacted starting materials. This work primarily focussed on the determination of seven perfluorocarboxylic acids (PFCAs) in two commercially available food contact papers: a di-perfluoro-alkyloxy-amino-acid and a perfluoroalkyl phosphate surfactant. In addition, the migration of the PFCAs into five food simulants from two commercial packages was evaluated. All seven PFCAs were detected in the range of 700-2220 µg kg⁻¹ of paper, while three perfluoroalkyl sulphonates were under the LOD. Results from migration tests showed that migration depends on paper characteristics, time and food simulant. The percentage of migration after 10 days at 40°C ranged from 4.8% to 100% for the two papers and different food simulants.

Non-visible print set-off of photoinitiators in food packaging: detection by ambient ionisation mass spectrometry.

Direct analysis in real time coupled to time-of-flight mass spectrometry (DART/TOF-MS) was used to detect the non-visible set-off of photoinitiators on the food contact surface of three different packages. The samples were intentionally under-cured to provoke set-off. Twelve commercially available photoinitiators were included in the ink formulations including α-amino-, morpholino, and α-hydroxy benzophenones, thioxanthones, aryl-phosphine oxide and three polymeric versions of these. Major colours of the packages' prints were analysed, as well as the specific areas of the inner surface in contact with them. Larger quantities of photoinitiators were detected on the food contact areas in contact with the darker colours of the images. Speed-cure 7005 and 4-phenylbenzophenone were the compounds most susceptible to set-off in each of the samples by DART response. An identification protocol for unknown set-off compounds was tested, resulting in the set-off detection of diethylene glycol ethers, erucamide and acrylates, and confirmed by solvent extraction GC-MS analysis. Finally, DART/TOF-MS was scanned across transects of the food contact side of packages to map the presence of photoinitiators. Higher photoinitiator signals were observed in patterns corresponding to the printed image, suggesting DART/TOF-MS might "image" print set-off.

Assessing direct analysis in real-time-mass spectrometry (DART-MS) for the rapid identification of additives in food packaging.

The ambient ionization technique direct analysis in real time (DART) was characterized and evaluated for the screening of food packaging for the presence of packaging additives using a benchtop mass spectrometer (MS). Approximate optimum conditions were determined for 13 common food-packaging additives, including plasticizers, anti-oxidants, colorants, grease-proofers, and ultraviolet light stabilizers. Method sensitivity and linearity were evaluated using solutions and characterized polymer samples. Additionally, the response of a model additive (di-ethyl-hexyl-phthalate) was examined across a range of sample positions, DART, and MS conditions (temperature, voltage and helium flow). Under optimal conditions, molecular ion (M+H+) was the major ion for most additives. Additive responses were highly sensitive to sample and DART source orientation, as well as to DART flow rates, temperatures, and MS inlet voltages, respectively. DART-MS response was neither consistently linear nor quantitative in this setting, and sensitivity varied by additive. All additives studied were rapidly identified in multiple food-packaging materials by DART-MS/MS, suggesting this technique can be used to screen food packaging rapidly. However, method sensitivity and quantitation requires further study and improvement.

Migration of fluorochemical paper additives from food-contact paper into foods and food simulants.

Fluorochemical-treated paper was tested to determine the amount of migration that occurs into foods and food-simulating liquids and the characteristics of the migration. Migration characteristics of fluorochemicals from paper were examined in Miglyol, butter, water, vinegar, water-ethanol solutions, emulsions and pure oil containing small amounts of emulsifiers. Additionally, microwave popcorn and chocolate spread were used to investigate migration. Results indicate that fluorochemicals paper additives do migrate to food during actual package use. For example, we found that microwave popcorn contained 3.2 fluorochemical mg kg(-1) popcorn after popping and butter contained 0.1 mg kg(-1) after 40 days at 4 degrees C. Tests also indicate that common food-simulating liquids for migration testing and package material evaluation might not provide an accurate indication of the amount of fluorochemical that actually migrates to food. Tests show that oil containing small amounts of an emulsifier can significantly enhance migration of a fluorochemical from paper.

Diffusion behaviour of additives in polypropylene in correlation with polymer properties.

The migration behaviour of polymer additives in 17 polypropylene (PP) samples is described. These samples cover the major types of PP used in food packaging. The diffusion coefficients of additives with relatively small molecular masses, M(r) = 136 (limonene), as well as the migration of typical antioxidants used in PP up to M(r) = 1178 (IRGANOX 1010), were measured at different temperatures. In addition, the diffusion data and percentages of xylene-soluble fractions were correlated. This enables a prediction of the migration behaviour of a PP sample by testing its 'isotactic index' with xylene. The results clearly indicate that PP can be subdivided, from the migration point of view, into the monophasic homopolymer (h-PP), the monophasic random copolymer (r-PP), and the heterophasic copolymer (heco-PP). The diffusion coefficients for r-PP are at least one order of magnitude higher than those of h-PP and comparable with the values for heco-PP. Upper limits for the diffusion values can be calculated based on the safety margin required by consumer protection laws.

Determination of 2,6-diisopropylnaphthalene (DIPN) and n-dibutylphthalate (DBP) in food and paper packaging materials from US marketplaces.

A gas chromatography-ion-trap tandem mass spectrometry procedure was developed for the determination of 2,6-diisopropylnaphthalene (DIPN) and n-dibutylphthalate (DBP) in domestic and imported paper packages and food sold in US marketplaces. The procedure involved ultrasonic extraction with dichloromethane, followed by analysis with the gas chromatography-ion-trap tandem mass spectrometry. Calibration curves for DIPN and DBP were achieved with concentrations ranging from 0.01 to 10 microg ml(-1) and the corresponding r(2) values were 0.9976 and 0.9956, respectively. In most of the fortified samples the recoveries were higher than 80% with a relative standard deviation (RSD) <10%. Using this procedure, it was found that less than 20% of the tested domestic packages and more than 60% of the tested imported food packages contained both DIPN and DBP. The concentrations of DIPN and DBP ranged from 0.09 to 20 mg kg(-1) and 0.14 to 55 mg kg(-1), respectively, with most of the DINP and DBP levels lower than 20 mg kg(-1). DIPN was not detected (<0.01 mg kg(-1)) in 41 food samples and DBP was only detected in two domestic and four imported food samples with concentrations ranging from <0.01 to 0.81 mg kg(-1).

Interfacial behavior of common food contact polymer additives.

Irganox 1076 (IN1076) and Irganox 1010 (IN1010), phenol containing species often used as antioxidant additives in food packaging polymers have both hydrophilic and hydrophobic functional groups. Consequently these additives are likely to absorb to surfaces where their free energy is minimized. Experiments described in this work examine the two-dimensional phase behavior and vibrational structure of IN1076 and IN1010 films adsorbed to the air/water interface. Surface pressure isotherms show that repeated compression of these films leads to continued irreversible loss of molecules and that on a per molecule basis, this loss is more pronounced for IN1076 than for IN1010. Differences in the surface properties of these two antioxidant additives are interpreted based on differences in molecular structure. Surface specific vibrational measurements of these organic films show very little conformational order, implying that even when closely packed, both antioxidant species have little affinity for forming highly organized domains. These findings have important ramifications for mechanisms that reduce antioxidant activity in polymers as well as descriptions of antioxidant blooming on polymer surfaces.

Rapid quantitative and qualitative confirmatory method for the determination of monofluoroacetic acid in foods by liquid chromatography-mass spectrometry.

A rapid quantitative method and a qualitative confirmatory method for the determination of monofluoroacetic acid (MFA) in complex food matrices are presented. The quantitative method utilizes a water extraction, solid phase extraction clean-up and liquid chromatography-mass spectrometry (LC-MS) for determination of MFA. This method showed a high degree of specificity, detecting MFA in all of the spiked samples, while none of the unfortified samples tested positive for MFA. Spike recoveries were high in all matrices analyzed, varying from 85 to 110%, and comparable at low (2mg/L) and high (20mg/L) spiking levels. Repeatability tests at the low spiking levels yielded RSDs of less than 5% for all matrices analyzed. The qualitative confirmatory method developed is conceptually different from the quantitative method, ensuring that both methods would not be subject to the same interferences. The method uses the formation of the hydrazide of MFA through derivatization with 2-nitrophenylhydrazine. This derivatization is well established for the determination of carboxylic acids, but this is the first application to the determination of MFA. The derivatization yield was matrix dependent, however the limit of detection (LOD) (0.8microg/L) was sufficient to confirm the presence of MFA in all spiked matrices. Repeatability tests at the low spiking levels yielded RSDs of approximately 7% for all matrices analyzed.

Diffusion of limonene in polyethylene.

Diffusion coefficients of limonene in various linear low-density polyethylene (LLDPE) and low-density polyethylene (LDPE) resins have been determined from sorption data using a thermogravimetric methodology. From these data, one can determine whether polymer synthesis parameters such as the choice of catalytic process or co-monomer result in substantial differences in how much food packaging additives might migrate to food. For example, LLDPE is currently manufactured using either one of two distinct catalytic processes: Ziegler-Natta (ZN) and metallocene, a single-site catalyst. ZN catalysis is a heterogeneous process that has dominated polyolefin synthesis over the last half-century. It involves a transition metal compound containing a metal-carbon bond that can handle repeated insertion of olefin units. In contrast, metallocene catalysis has fewer than 20 years of history, but has generated much interest due to its ability to produce highly stereospecific polymers at a very high yield. In addition to high stereospecificity, metallocene-catalysed polymers are significantly lower in polydispersity than traditional ZN counterparts. Absorption and desorption testing of heat-pressed films made from LLDPE and LDPE resins of varying processing parameters indicates that diffusion coefficients of limonene in these resins do not change substantially.

Perfluorochemicals: potential sources of and migration from food packaging.

Perfluorochemicals are widely used in the manufacturing and processing of a vast array of consumer goods, including electrical wiring, clothing, household and automotive products. Furthermore, relatively small quantities of perfluorochemicals are also used in the manufacturing of food-contact substances that represent potential sources of oral exposure to these chemicals. The most recognizable products to consumers are the uses of perfluorochemicals in non-stick coatings (polytetrafluoroethylene (PTFE)) for cookware and also their use in paper coatings for oil and moisture resistance. Recent epidemiology studies have demonstrated the presence of two particular perfluorochemicals, perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in human serum at very low part per billion levels. These perfluorochemicals are biopersistent and are the subject of numerous studies investigating the many possible sources of human exposure. Among the various uses of these two chemicals, PFOS is a residual impurity in some paper coatings used for food contact and PFOA is a processing aid in the manufacture of PTFE used for many purposes including non-stick cookware. Little information is available on the types of perfluorochemicals that have the potential to migrate from perfluoro coatings into food. One obstacle to studying migration is the difficulty in measuring perfluorochemicals by routine conventional analytical techniques such as GC/MS or LC-UV. Many perfluorochemicals used in food-contact substances are not detectable by these conventional methods. As liquid chromatography-mass spectrometry (LC/MS) develops into a routine analytical technique, potential migrants from perfluoro coatings can be more easily characterized. In this paper, data will be presented on the types of perfluoro chemicals that are used in food packaging and cookware. Additionally, research will be presented on the migration or potential for migration of these chemicals into foods or food simulating liquids. Results from migration tests show mg kg(-1) amounts of perfluoro paper additives/coatings transfer to food oil. Analysis of PTFE cookware shows residual amounts of PFOA in the low microg kg(-1) range. PFOA is present in microwave popcorn bag paper at amounts as high as 300 microg kg(-1).

Migration of a UV stabilizer from polyethylene terephthalate (PET) into food simulants.

The migration characteristics of the UV stabilizer Tinuvin 234 (2-(2H-benzotriazol-2-yl)-4,6-bis (1-methyl-1-phenylethyl)phenol) into food simulants has been measured from polyethylene terephthalate (PET) using HPLC with UV detection. Ethanol/ water, isooctane and a fractionated coconut oil simulant (Miglyol) were used as food simulating solvents. The migration characteristics were measured at temperatures in the range of 40-70 degrees C. Diffusion coefficients were determined to be in the range of 1 x 10(-14) cm2 s(-1) to 1 x 10(-18) cm2 s(-1). At 40 degrees C, the amount of migration into 95% ethanol after 10 days was 2 microg dm(-2). Isooctane is determined to be a good fatty food simulant that provides similar results for PET to those of fatty foods.

Effects of gamma- and electron-beam irradiation on semi-rigid amorphous polyethylene terephthalate copolymers.

Two semi-rigid amorphous polyethylene terephthalate copolymer materials (in both sheet and powder forms) containing 3% 1,4-cyclohexane dimethanol (CHDM) and 31% CHDM were irradiated at 5, 25 and 50 kGy at ambient temperature with a (60)Co radiator or an electron-beam accelerator. After irradiation, volatiles were determined using static headspace sampling with capillary gas chromatography and mass selective detection or flame ionization detection (HS/GC/MSD or FID). Non-volatiles were extracted with 10% aqueous ethanol and 100% n-heptane food-simulating solvents, maintained at 40 degrees C for up to 10 days. The non-volatiles in the materials and those migrating into the food-simulating solvents were determined by high-performance liquid chromatography (HPLC) with ultraviolet and/or photodiode array detection. The results obtained from the HS/GC/MSD suggest that no new chemicals were detected by either gamma- or e-beam irradiation when compared with non-irradiated specimens. The major volatiles in the copolymers were acetaldehyde and 2-methyl-1,3-dioxolane. The concentrations of acetaldehyde increased from 1.24-1.96 mg kg(-1) to 1.94-3.65, 3.52-7.23 and 5.45-15.37 mg kg(-1) after exposure to 5, 25 and 50 kGy doses, respectively. The concentrations of 2-methyl-1,3-dioxolane decreased from 2.49-5.26 mg kg(-1) to 2.07-3.13, 1.33-2.14 and 0.64-2.24 mg kg(-1) after exposure to 5, 25 and 50 kGy doses, respectively. The results of analysis of the copolymers for non-volatiles show that irradiation did not produce any new detectable non-volatile chemicals. A 5 kGy dose had no detectable effect on either copolymer. The 25 and 50 kGy doses had slightly different effects with respect to gamma- and e-beam irradiation on low MW oligomers. However, these increased doses did not significantly affect migration. The concentration of most low molecular weight oligomers migrating into 10% ethanol and 100% heptane was < or =2 ng g(-1) of each oligomer for both copolymers. The cyclic trimer migrating from the 3% CHDM copolymer was approximately 4 ng g(-1); it was 3 ng g(-1) for the 31% CHDM copolymer. The overall results suggest that irradiation significantly increased levels of acetaldehyde but had no effect on non-volatile compounds migrating into food simulants.

Evaluating the potential for recycling all PET bottles into new food packaging.

To evaluate the feasibility of recycling all PET bottles into food packaging, realistic estimates of the maximum concentration of contaminants that might be expected in the polymer are needed. To estimate the maximum concentration of a contaminant that might be in PET from the storage of non-food substances, sorption experiments into two types of PET were performed. These test materials were 0.8mm thick amorphous PET (a relative sink for contaminants) and commercial PET bottle wall. Using a commercial shampoo containing 1% lindane (C6H6Cl6), the test materials were stored in contact with the shampoo at 20 and 40 degrees C for 231 days. This commercial shampoo also represents an extreme case because it contains 7% acetone, a solvent which swells PET, further enhancing sorption of chemicals. Additional sorption experiments into PET were performed by preparing solutions of 10% toluene in Miglyol (a fractionated coconut oil), 10% benzophenone in Miglyol, 5% 2-butoxyethoxy ethanol (2-BE) in 50/50 water/ethanol, and 10% methyl stearate in heptane. Sorption data from the shampoo into PET illustrate Fickian behaviour. Specifically, the amount of sorption at room temperature is approximately40 times less than that at 40 degrees C. The amount of lindane sorbed into PET from the shampoo after 231 days was 0.1 and 3.7 mgdm(-2) at 20 and 40 degrees C respectively. These values correspond to 28 and 765 mg kg(-1) on a mass/mass basis. All sorptions are within the ranges measured and published by other authors using surrogate contamination testing schemes. Additionally, actual bottles from recycle bins were analysed for the amout of contamination. Results are discussed in terms of potential consumer exposure to non-food contaminants in food containers made of recycled PET and in relation to the surrogate testing methods recommended by the Food and Drug Administration (FDA) for determining the compatibility of a PET recycling process to produce containers suitable for food-contact use.

Determination of the diglycidyl ether of bisphenol A and its derivatives in canned foods.

Migration of the diglycidyl ether of bisphenol A (DGEBA) to food from can enamels and can pull-top seals is reported. Derivatives of DGEBA are also determined in some foods. Levels of DGEBA in the foods surveyed in this study range from nondetected (<0.3 ppb) to 50 mg/kg as determined by liquid-liquid extraction or solid-phase extraction coupled with high-pressure liquid chromatography using fluorescence detection. Confirmation of the analytes is by gas and/or liquid chromatography with mass spectral analysis. Fourier transform infrared spectroscopy with 30 degrees specular reflectance/transmittance is used to characterize the coated food contact surfaces. Stability studies with DGEBA in water, acid, and saline solutions show conversion to the hydrolysis products and chloro adducts occurs readily. The presence of DGEBA derivatives in food demonstrates that analysis for DGEBA migration alone is not a good indicator of total migration from can coatings to foods.

Methods and approaches used by FDA to evaluate the safety of food packaging materials.

In the Federal Register of July 17 1995 (60 FR 36582), the US Food and Drug Administration (FDA) established a 'threshold of regulation' process. This process was established for determining when the extent of migration to food is so trivial that safety concerns would be negligible. The process exempts materials in food-contact articles whose use results in dietary concentrations at or below 0.5 ppb (microgram/kg) from the food additive listing regulation requirement. Carcinogens or substances that may be carcinogens are excluded from this regulation. This paper explores some of the ramifications of the threshold of regulation policy with respect to traditional migration testing. It examines the use of the threshold approach and migration modelling to estimate food additive exposures. These results indicate that modelling may be a reasonable alternative to traditional migration testing.

Migration of residual contaminants from secondary recycled poly(ethylene terephthalate) into food-simulating solvents, aqueous ethanol and heptane.

This study measured the migration of benzene, butyric acid, dodecane, octadecane, tetracosane, diazinon, lindane, and copper (II) ethyl hexonate from poly(ethylene terephthalate)(PETE) sheets into the food simulants, 8% ethanol/water and n-heptane. The contaminated PETE sheets were extruded from PETE chips that had been previously contaminated but were washed, dried, and remelted. The level of these contaminants remaining in the extruded sheets ranged from benzene at 0.6 mg/kg to copper salt at 24 mg/kg. The extraction data demonstrate that migration of the residual contaminants from the extruded PETE sheets resulted in concentrations lower than 10 micrograms/kg in the food simulants. At very high residual concentrations of butryic acid (147 mg/kg) and benzene (218 mg/kg) in sheets made from unwashed PETE, higher amounts of the contaminant migrated into the food simulants. This migration resulted in contaminant concentrations exceeding 10 micrograms/kg and suggests that unwashed recycled PETE may not comply with FDA requirements. The crystallinity of extruded PETE sheets in this study ranged from 5 to 15%, which is lower than that of most commercial PETE (30%). Therefore, the migration data obtained from these test samples represent the most severe conditions for conservative exposure evaluations.

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.

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.