Quantification of quaternary mixtures of alcohols: a comparison of reflectometric interference spectroscopy and surface plasmon resonance spectroscopy

In this paper the quantification of quaternary mixtures of the homologous series of the alcohols methanol to n -butanol in the gaseous phase is presented. Time-resolved reflectometric interference spectroscopy (RIfS) and surface plasmon resonance spectroscopy (SPR) are used. An array consisting of two layers of a size-selective microporous polymer (Makrolon ® ) plus the polar polymer polyetherurethan (PUT) is used for RIfS measurements. The time-dependent kinetics of sorption and desorption of the analytes is evaluated by the use of neural networks. As the time-dependent sensor signals differ significantly for each analyte, quantifications with only a single microporous layer are possible. Thus, measurements using a thinner microporous layer for the SPR set-up are also performed, showing faster sorption and desorption. Therefore, measurements can be performed much faster by using the SPR set-up. It can be shown that the quantification of the quaternary mixtures can be successfully performed using a single-sensor set-up for both methods.