Food contact plastics, analysis

Analysis of substances migrating from food contact plastics is possible at very low levels in real foods. Volatile species are the easiest to determine. 

Apart from routine quality control actions, additive analysis is often called upon in relation to testing additive effectiveness as well as in connection with food packaging and medical plastics, where the identities and levels of potentially toxic substances must be accurately known and controlled. Food contact plastics are regulated by maximum concentrations allowable in the plastic, which applies to residual monomers and processing aids as well as additives [64-66]. Analytical measurements provide not only a method of quality control but also a means of establishing the loss of stabilisers as a function of material processing and product ageing. 

For standard or proprietary polymer additive blends there is the need for analytical certification of the components. Blend technology has been developed for two- to six-component polymer additive blend systems, with certified analytical results [81]. Finally, there exist physical collections of reference additive samples, both public [82] and proprietary. The Dutch Food Inspection Service reference collection comprises 100 of the most important additives used in food contact plastics [83-85]. Reference compounds of a broad range of additives used in commercial plastics and rubber formulations are generally also available from the major additive manufacturers. These additive samples can be used as reference or calibration standards for chromatographic or spectroscopic analysis. DSM Plastics Reference Collection of Additives comprises over 1400 samples. 

Another application of ICP-MS in the area of food safety is the evaluation of food contact materials. Q [86] and TOF [87] mass spectrometers have been employed in the compositional analysis of paper and board material intended for food contact. Studies on the migration of metals from food contact plastics using food simulants and ICP-MS detection have also been reported. One of them showed how to analyze different simulants without the need of any time-consuming preparation, that is, aqueous acetic acid (3 percent w/v) directly, aqueous ethanol (15 percent v/v) after proper dilution, the olive oil simulant following emulsion preparation by means of tetralin and Triton X-100 [88]. 

Kawamura et al. [81] have surveyed nonylphenol by GC-MS (with quantification by GC-SIM-MS) in 207 samples of food contact plastics and baby toys. Crompton [43] has described the quantitative GC analysis of residual vinylchloride, butadiene, acrylonitrile, styrene and 2-ethyIhexylacrylate in polymers by solution headspace analysis. Considerably greater sensitivities and shorter analysis times were obtained using the headspace analysis methods than were possible by direct injection of polymer solutions into a GC. Similarly, various residual hydrocarbons (10 ppm of isobutane, n- and isopentane, iso- and neohexane) in expanded PS were determined by GC analysis of a solution of the sample with hydrocarbon internal standards accuracies of 5 to 10% were reported [82]. Residual n- and isopentane (0.001%) in expandable and expanded PS were also determined by a solvent-free procedure consisting of heating the polymer at 240°C in a sealed tube, followed by HS-GC calibration against known blends of n- and isopentane and n-undecane internal standard [82]. 

The enforcement in Denmark of EU Directives on food packaging materials is discussed. Enforcement activities considered include studies of total migration from food contact materials, migration from kitchen-and tableware made of melamine plastics and migration of di(2-ethylhexyl)adipate from plasticised PVC films. Activities which need to be undertaken to increase the effectiveness of enforcement activities in the field of migration are described, including development of selfinspection programmes in industry, European network of enforcement, more rapid analysis and provision of information to the consumer. 2 refs. 

JiCKELLS, s. M., CREWS, c., CASTLE, L. and GILBERT, J. Headspace analysis of benzene in food contact materials and its migration into foods from plastics cookware , Food Additives and Contaminants 1990 7(2) 197-205. 

Fordham PJ, Gramshaw JW, Castle L. Analysis for organic residues from aids to polymerization used to make plastics intended for food contact. FoodAddit Contam 2001 18(5) 461-71. 

Uses Alkali mfg. of lime neutralizer paper opacifier putty tooth powds. whitewash Portland cement filler, extender in paints, rubber, plastics, caulks, cements, ceramics, coatings insecticides in chemical analysis precipitant in waste treatment filler pigment coagulant, flocculant in potable water treatment foods (nutrient, dough conditioner, yeast food, colorant, alkali, calcium fortification, buffer, anticaking agent, stabilizer) pharmaceuticals (alkali, neutralizer, colorant, opacifier, tablet/capsule diluent, antacid, antidiarrheal medicine food-contact applies. 

The analysis of foods, beverages, or simulant liquids that have been in contact with plastics either in extraction tests or during the shelf life of a packaged commodity presents many fascinating and all too often difficult problems. Thus, the substance to be determined usually occurs at very low concentrations and several extracted substances may occur in the same food or simulant. For example, the extract of a PS may contain an antioxidant, an ultraviolet... 

The manufacturer of plastic packaging has to know in what amounts an additive migrates into food this amount must be determined by simulating all conditions in which it is used (temperature, contact time, food simulants). The food simulants used are distilled water, aqueous acetic acid, aqueous ethanol, and natural fats or oils 95% ethanol and ethyl acetate are recommended as fat simulants for PO. Only 10, 50, or 100 ppb (parts per billion) of additives are tolerated in food. Numerous methods of additive analysis have been developed [1,60]. 

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