Extractability Testing in the USA

The US legislation has been adopted outright or in a modified form by other countries. In the US food law is strongly inclined to Statute Taw. Although each state can legislate separately, in practice the Federal Law usually prevails which has considerable advantages in interstate commerce. Many states have their own law which is identical to the Federal Law. 

Details of the US migration test procedures have been published [7-12]. A typical example of the application of a migration test procedure has been described by Lin and co-workers [13]. Migration studies were performed by determining acrylate monomers and oligomers in extractants from electron beam curable acrylate coatings. The cell extraction method used was that proposed by the FDA Centre for Food Safety and Applied Nutrition www.cfsan.fda.gov). Stainless steel extraction cells with Teflon spacers of 30 ml volume and 50 cm opening for the extraction solvent 

The principal United States law is the FDA Food, Drug and Cosmetic Act 1938 and its numerous amendments [14]. This is designed to provide food that is safe and wholesome to the people, honestly labelled and properly packaged. Decisions have to be made as to the appropriate extraction liquids, test temperatures and whether the extraction test is carried out by single or double sided exposure of the test panels to the extractant liqnid. 

Nerin and co-workers [15] in their stndy of migration of various phthalate plasticisers from paper board into FDA extraction liquids used various test conditions including 10 days at 40 °C, 1 hour at reflux temperature for all aqueous stimulants, 10 days at 40 °C and 1 hour at 175 °C for olive oil and 2 days at 20 °C and 3 hours at 60 °C for the isooctane stimulant. 

The decision between single or double sided extraction is based upon the construction of the test material, and its thickness. Structures greater than 0.05 cm thick are considered by the FDA to be infinitely thick. Single-sided extractions are most often used for coated materials or structures less than 0.05 cm thick. Two pieces of materials are separated by an inert spacer, thus defining a volume. This layered construction is secured so that the volume can be filled with the food simulating solvent. Donble-sided extractions are by far the most common type, i.e., when specimen thickness exceeds 0.05 cm. FDA requirements stipulate that the ratio of food simulating solvent volume to surface area of extracted material must be near to 0.3 ml/cm.  

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