Overall migration testing

The gravimetric determination of the residue from overall migration tests or extraction tests is at the milligram scale. As mentioned above, the EU limit for overall migration is 60 mg/kg. With some caveats, measuring at these levels is relatively simple in even the most basic laboratory and official methods are well described. 

The whole area of specific migration determinations can be subdivided in two phases (i) the pre-analytical migration exposure phase, which is more or less identical to that necessary for overall migration determination and (ii) the pure analytical phase, where the specific migrant must be determined in the respective food or simulant as precisely and reproducibly as possible. This pure analytical migration test phase comprises many considerations to be made and includes so many technical possibilities that it deserves to be described in an own comprehensive section (see Section 10.2). 

In 1982 the first directive in the sector, Council Directive 82/711/EEC, laying down a precise reference framework for the system of checking specific and/or overall migration, was adopted. It establishes what simulating liquids (i.e. liquids which can simulate the extractive capacity of foodstuffs), contact times and temperatures are to be used in migration tests performed under standardized conditions. This reference framework, which may seem unduly rigid given the innumerable conditions of contact in reality, was made flexible by the inclusion of a clause which permits Member States to depart from the standard conditions where these prove to be inadequate in the case in question either for technical reasons or because they are too different from the real conditions. 

Several types of etched capillaries have been tested with respect to within column reproducibility. For example, the reproducibility of the migration times for 151 consecutive injections of the proteins lysozyme and ribonuclease A was tested on an etched Ci8 modified column at pH = 3.0 [20]. It was found that both solutes gave no discernible increase or decrease in migration time (tM) and its overall reproducibility... 

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