Migration overcoming

Additives such as antioxidants and photostabilizers of low-molecular weight face two major problems (1) they may evaporate during high temperature moulding and extrusion process or (2) they may migrate to the surface of the plastic and get extracted. There are, in general, three ways of overcoming these problems. 

Earlier tapes frequently suffered from the migration of plasticiser from the tape to the adhesive with the result that the tape became detached from the metal, to which the adhesive remained attached. This has now been overcome by using a barrier between the tape and adhesive which itself may contain inhibitors against soil bacteria. 

The difficulty in controlling the regiochemistry during radical-denitration of allylic nitro compounds is well known. The migration of the double bond is a serious problem, as shown in Eq. 7.96. This problem is overcome by a hydride transfer reaction in the presence of a palladium catalyst (Eq. 7.97).140... 

One concern relating to SDS-PAGE-based purity analysis is that contaminants of the same molecular mass as the product will go undetected as they will co-migrate with it. Two-dimensional electrophoretic analysis would overcome this eventuality in most instances. 

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