Near-IR Multiplex Bandpass Spectrometer Utilizing Polymer Filters

Abstract

A simple near-infrared spectrometer is described that utilizes ordinary polymer sheets as near-IR spectral filters. Examples of filter materials include polymethyl methacrylate, polyvinyl chloride (PVC), and organic solutions immobilized in a PVC matrix. The polymers were prepared by using solvent-molding techniques as well as with a thermoforming process. Each filter substance passes multiple bands of near-IR radiation. The performance of the spectrometer is demonstrated in selected quantitative and qualitative near-IR analytical applications. The applicability of the designed multiplex bandpass spectrometer in determining trace levels of water in methanol, dimethyl sulfoxide, and propylene glycol is examined. Additionally, the utility of the spectrometer in the determination of glucose concentration in aqueous solutions is studied.