ABSTRACT:The in vitro hydrolysis of poly(1,2-propylene adipate) by digestive fluid liquids was studied to assess the safety of polymeric plasticizers that could migrate into food. A high extent of hydrolysis was obtained with freshly prepared intestinal fluid solutions. High performance size exclusion chromatography analysis indicated that the bulk plasticizer completely disappeared and that low molecular weight oligomers were formed within 4 h. Hydrolysis did not result in a significant conversion to the free monomers, like adipic acid, as was shown by gas-phase chromatography. Measurements by NMR indicated that the cleavage selectively occurred at primary ester linkages. Fractionation of the hydrolysis products on silica gel gave six oligomeric fractions, which were recovered and analyzed. The absolute molecular weight of the plasticizers and the average molecular weight of the hydrolysis products were evaluated using proton NMR. Hydrolysis did not take place (Ͻ2%) under simulated gastric and saliva conditions.

S.ummaryThe n.m.r. spectra of protonated a-chloroacetaldehyde and a-chlorobutyraldehyde in strong acid solution show the presence of two isomeric species, one of which can be explained in terms of intramolecular hydrogen bonding between the proton on oxygen and the chlorine atom.