Polyethylene terephthalate is commonly used in the manufacturing of beverage containers. These containers can be recycled and used to make new containers for beverages. Frequently, ingredients from the beverage migrate into the plastic. These compounds can remain in the plastic after the PET has been recycled. The PET is typically turned into pellets or flakes. These residual compounds can wind up in the new beverage containers and eventually migrate into the beverage or water, causing off-odors or flavors in the beverage.

Several compounds are of concern in recycled PET. These include acetaldehyde, benzene, and limonene. Acetaldehyde is a thermal degradation product of the PET polymer generated during polymerization and during the melt processing stage of production. It can become trapped in the polymer as it cools, then leach from the walls of the bottle into the contents once the bottle is filled. Benzene is a polymer degradation product that can be found in recycled PET. It is a known carcinogen; monitoring ist concentration in recycled PET is important for safety concerns. Limonene is a common flavor compound found in many citrusflavored drinks. It can migrate into a PET bottle from the beverage and remain in the pellets or flakes after recycling.

Several techniques have been proposed for monitoring the Level of these compounds in recycled PET. These include off-line and on-line direct thermal extraction (DTE) and multiple headspace extraction-static headspace analysis (MHE-SHS).

This study will utilize the GERSTEL MPS sampler, TD 3.5+ thermal desorber, and CIS 4 inlet for static headspace and direct thermal extraction for the analysis of acetaldehyde, benzene, and Limonene in recycled PET. For off-line direct thermal extraction, the GERSTEL Thermal Extractor (TE-2) was used to collect samples onto thermal desorption tubes. The tubes were analyzed using the TD 3.5+.