Determination of eugenol diffusion through LLDPE using FTIR-ATR flow cell and HPLC techniques

A time-resolved Fourier Transform Infrared-Attenuated Total Reflectance Spectroscopy (FTIR-ATR) technique was set up and used to study the diffusion of eugenol through Linear Low Density Polyethylene (LLDPE) at 16, 23 and 40 °C. The 1514 cm−1 peak for eugenol (aromatic -CC- stretching) was monitored over time and used to determine the diffusion coefficient (D). The Fickian model was found to fit well to the experimental data and the D value of eugenol through LLDPE was found to be between 1.05 ± 0.01 and 13.23 ± 0.18 × 10−10 cm2/s. The FTIR-ATR results were compared with one and two side diffusion process using a permeation cell and quantified by High Performance Liquid Chromatography (HPLC) technique. Eugenol sorbed in LLDPE samples at different times, was extracted in methanol and the concentration determined by HPLC. The diffusion coefficient by both two-sided and one-sided HPLC technique was found to be approximately three times higher than the FTIR-ATR values although they were in the same order of magnitude of 10−10 cm2/s. The difference between the FTIR-ATR and HPLC results was mainly attributed to difference between the two measuring techniques.