Migration testing purpose

These workers stress that high temperatures encountered for limited periods in practice, (e.g. during pasteurisation, sterilisation or preparation of foodstuffs in plastics packs) must be simulated by use of appropriate test temperatures and times. Moreoever, experimental films made only for test purposes should be of the same thicknesses as the article that will actually be used, since the thickness of the film has a definite influence on the amount of additive migrating. The extent of migration also depends on the physico-chemical properties of the test material, including its density, surface quality and crystallinity. Test specimens, both of films and plastics containers should therefore be made under standard production conditions. 

The purpose of sample acceptance criteria is to confirm that the run for a test article is suitable for quantification. The corrected peak area of the sample should be within linear range of the assay the baseline should be suitable for integration the corrected peak percentage should be in a reasonable range. Again, for a purity assay, migration time is usually not a critical parameter. 

Migration is a factor which must be taken into account in selecting the best dyes for the purpose. The test used by Ris etaZ.was to boil three dyra pieees with undyed material of equal weight in three separate beakefs.-A blank dye liquor was used, containing all the additions exeept the dyestuff. The samples were withdrawn from the three beakers in turn at intervals of 30, 60 and 90 minutes, and the amount of eolour on the dyed and undyed samples assessed. From this information eurves of thtf type shown in Fig. 15.8 and 15.9 are obtained. In each case the loss of depth of... 

The next step is to test one or more of the selected concrete compositions using a compliance test that determines the chloride-penetration resistance. DuraCrete has adopted the rapid chloride migration (RCM) test for this purpose [21,25], which is a short-term test based on acceleration of chloride penetration by an electric field. 

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