On the Extractability of Di-Alkyl Tin Compounds from Rigid Polyvinyl Chloride Containers

Abstract

Organotin compounds, such as di-n-butyl tin and di-n-octyl tin derivatives, are effective stabilizers in the manufacture of rigid PVC containers for food packaging use. Certain derivatives, however, have biological activities in food hygienic sense.
The determination of minute amount of di-alkyl tin compounds migrated from container into food-simulating media was successfully carried out by dithizone-extraction and succeeding colorimetric measurement in 1, 2-dichloroethane. Inhibition of heavy metals was eliminated by EDTA-extraction in borate buffer of pH 8.4.
Rigid PVC containers, including different types and concentrations of di-n-alkyl tin stabilizers were prepared, in which Various food-simulated solutions were packed and stored at a temperature of 50°C. The stabilizer migrated from PVC into the solution was determined after aging.
The extent of migration was larger in hydrophobic solution than in hydrophillic media. The extraction of di-n-butyl tin increases with increase of the content formulated in PVC, while di-n-octyl tin was scarcely extracted. Effect of other additives on the migration was observed for di-n-octyl tin-stabilized system in fat-simulated medium.