Development of Electronic Nose Method for Evaluation of Residual Solvents in Low-density Polyethylene Films

摘要

Flexible packaging films containing high levels of residual volatile organic compounds (VOCs) can alter the flavour and odour of packaged foods. Currently, a range of gas chromatographic techniques and sensory evaluations are used for assessing the residual VOCs in packaging films. An objective method for assessing the residual solvents from low-density polyethylene (LDPE) was developed using an Alpha MOS Fox 3000 electronic nose (e-nose) equipped with 12 metal oxide semiconductor sensors. Three VOCs, ethyl acetate, ethyl alcohol and toluene, were chosen as models for solvents of interest in flexible food packaging analysis. LDPE film samples were spiked with single and binary mixtures of solvents and analysed using the e-nose and by GC-FID (HP 6890; Hewlett-Packard Co., Wilmington, DE). The responses obtained from the e-nose were processed using principal component analysis (PCA) and discriminate factorial analysis (DFA) in order to identify the residual solvents. Partial least squares analysis (PLS) was also used to quantify the amount of residual solvent and to correlate the e-nose results with gas chromatography, which is currently the standard method for determining residual VOCs in packaging films. There was good agreement between the e-nose responses and gas chromatography results for single solvents (r = 0.90-0.98). The technique also worked for binary solvent mixtures (r = 0.84-0.99). The electronic nose can be a viable alternative to traditional techniques while providing simplicity and objectivity, which would be extremely advantageous in routine quality control of residual solvents.