Migration Overall

Where specific Regulations are in force then the methods associated with the Regulations shall be accredited if the control laboratory wishes to offer enforcement of the Regulations to customers. Examples of these are methods of analysis for aflatoxins and methods of analysis for specific and overall migration for food contact materials. 

The overall migration in CE is determined by the combined effect of the effective and the electroosmotic mobility. The apparent electrophoretic mobility is therefore used as the... 

The lack of ionic mobility data causes a serious inconvenience when the ion conduction ability of an electrolyte is evaluated, because the measured conductivity is the result of the overall migration of both anions and cations, while for lithium batteries only the portion of the current that was carried by the lithium cation matters. This portion of the current from lithium ion movement, which determines the... 

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. 

Monoliths containing two significantly different percentages of dimethyldiallylam-monium chloride 15 were recently prepared in order to control the EOF component of the overall migration rate of proteins [31]. These charged moieties were incorporated into the monolith during a later stage of the preparation process. This process appeared to be well suited to achieve monolith with properties required for the desired separations (vide supra). 

Numerous examples of measured overall migration values have been collected and the interested reader can find a published data compilation summarized for different polymer types (Van Battum 1996). 

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). 

Simal Gandara J, Lopez Mahia P, Paseiro Losada P, Simal Lozano J and Paz Abuin S, 1993, Overall migration and specific migration of bisphenol A diglycidyl ether monomer and m-xylylenediamine hardener from an optimized epoxy-amine formulation into water-based food simulants. Food Additiv. Contam. 10 (5), 555-565. 

For additives, on the other hand, the list is a partial list currently comprising 289 substances fully evaluated by the SCF whose toxicological characteristics do not necessitate the imposition of any restriction on use other than the overall migration limit. 204 additional substances, fully evaluated by the SCF and 185 of which require a restriction on their use according to the SCF, will be added to the list before long. All of the more important information on the evaluation of substances is to be found in the document entitled Synoptic which is to be distributed on the Internet (address http //cpf.jrc.it/webpack/). 

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. 

The overall migration velocity in electrophoresis, is the sum of the electrophoretic velocity of the charged separand, uep, and the electrosmotic velocity measured by a neutral tracer, u, as both migration processes take place simultaneously. Thus... 

An additivity relationship for the separative and nonseparative parts of the overall migration process that is equally applicable to HPLC and CZE arises naturally upon introduction of virtual migration distances, which represent the... 

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