Rapid analysis of packaging laminates by near-infrared spectroscopy

Abstract

Qualitative and quantitative analyses of three components of a packaging laminate have been obtained by the application of near-infrared spectroscopy. The absence of any of the components (cast polypropylene, linear low density polyethylene and nylon) could be detected with ease. A semi-quantitative analysis of the components, using a simple linear regression calibration, gave good estimates of the number of layers of a given type when multiple layers of components were presented to the spectrometer. This was improved to a quantitative method by calibration using layers of components of known thickness. The precision of the method was calculated to be 10% for a single determination.