Determination of high- and low-molecular-mass plasticisers in stretch-type packaging films

A single analytical procedure is presented for determination of so-called monomeric plasticisers such as di(2-ethylhexyl) adipate, polymeric plasticisers such as poly(butylene adipate), and secondary plasticisers such as epoxidised soybean oil. The plasticisers are extracted from the film with concurrent derivatisation. Ester linkages are cleaved by treatment with potassium hydroxide in ethanol, epoxide moieties are opened using hydrochloric acid generated in situ by addition of acetyl chloride and, lastly, hydroxy groups are converted to silyl ethers using bis(trimethylsilyl)trifluoroacetamide. This reaction sequence is conveniently performed sequentially on a single sample leading to products that can be measured in a single GC analysis. The method has been applied to samples of known provenance and in a large survey of retail stretch-type films. The combined method offers significant savings in time compared with the separate analytical methods published earlier for monomeric and polymeric poly(vinyl chloride) plasticisers. The method is quantitative and gives results in good agreement with these earlier procedures.