GC×GC-HRT was used to gauge the relative abundance and tentatively identify molecules in the methanol extract. This approach chromatographically separates components relative to their vapor pressure and polarity, yielding ordered two-dimensional chromatograms with a highresolution mass spectrum for each peak. The GC×GC-HRT chromatogram of the methanol extract contained 11 peaks that can broadly be binned into two elution windows. Peaks 1 through 6 were grouped in a narrow band with limited retention in both dimensions. Peaks 7 through 11 eluted along a wide range of retention times. ). The tentative occurrence of isocyanates, anilines, and amides on a 2,6diisopropylphenyl structural unit likely indicates that these relate to bis(2,6diisopropylphenyl)carbodiimide (CAS# 2162-74-5), an anti-hydrolysis additive used for polyester stabilization. Carbodiimides react with carboxylic acids to form N-acylureas that can fragment into amides and isocyanates at elevated temperatures (such as during melt processing). In particular, the absence of bis(2,6-diisopropylphenyl)carbodiimide and the presence of 2,6-diisopropylphenyl isocyanate and 2,6-diisopropylaniline agrees with previous reports on the presence of the compound in plastic leachates. Cycloaliphatic epoxides are commonly used as hardeners/crosslinkers with PCL. Peak 9 was tentatively identified as 4,4′-butylidenebis(3-methyl-6-t-butylphenol) (Figure ) and regular addition of m/z 114 with later eluting peaks. Additionally, these peaks formed a "fairway" in the GC×GC chromatogram, a typical chromatographic feature for compounds of the same class with increasing molecular weight. These results reinforce that plastics are not exclusively single compounds but are diverse, complex mixtures of many known and unknown compounds. Previous work has shown that extractables from commercially produced PCL can include caprolactone (CAS# 502-44-3), 6-hydroxyhexanoic acid (CAS# 1191-25-9), and phthalates (unspecified). One of the most conventional synthesis routes of PCL uses stannous 2ethylhexanoate (CAS# 301-10-0) as a catalyst for the ring-opening polymerization of caprolactone. Residual -caprolactone, 6-hydroxyhexanoic acid, 2-ethylhexanoic acid (CAS# 149-57-5), and phthalates were not detected.