Ronald P. D’Amelia^1,, Matthew Neryaev¹, Michael Leone¹, Mary T. Rooney¹

Phthalates are chemicals primarily used as plasticizers in polymers, especially polyvinyl chloride (PVC). Phthalates are also found in pharmaceuticals, personal care products, and other daily consumer goods to improve flexibility and durability. However, certain phthalates are associated with potential health risks, such as endocrine disruption and reproductive damage. The key factor in phthalate toxicity is the substance’s chemical makeup; however, molecular weight (MW) influences its release and absorption upon exposure. Generally, higher MW phthalates leach less readily, whereas lower MW phthalates leach more readily. Here, we focus on the compositional analysis of pure and binary mixtures of short-chain phthalates (Dimethyl Phthalate (DMP), Diethyl Phthalate (DEP), Dipropyl Phthalate (DPP), and Dibutyl Phthalate (DBP)), due to their tendency to migrate from plastic products into their surrounding environments and water sources. Gas chromatography with flame ionization detection (GC-FID), along with quantitative proton nuclear magnetic resonance (¹H NMR) and Fourier-transform infrared (FTIR) spectroscopy, was used to quantitatively distinguish between these compounds and determine their relative concentrations when present in binary mixtures. GC-FID chromatograms, ¹H NMR spectra, and FTIR spectra were first obtained using pure phthalates (DMP, DEP, DPP, and DBP), and then for 6 sets of binary mixtures of varying gravimetric weight percent. GC-FID produced fully resolved chromatograms, while ¹H NMR and FTIR provided chemically specific fingerprints unique to each phthalate, with deconvolution applied to overlapping peaks to aid quantification. Quantification based on integrated peaks and spectral intensities showed a strong linear correlation between gravimetrically achieved weight percents and experimentally calculated weight percents. This correlation confirms the utility of GC, ¹H NMR, and FTIR in the identification and quantification of these phthalates.

Gas Chromatography (GC), Protonnuclear magnetic resonance spectroscopy (1HNMR), Fourier-transform infrared spectroscopy (FTIR), short-chain phthalate diesters, dimethylphthalate (DMP), diethyl phthalate (DEP), dipropylphthalate (DPP), dibutyl phthalate (DBP)