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

Abstract

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.

The Theoretical Concept of Polarization Reflectometric Interference Spectroscopy (PRIFS): An Optical Method to Monitor Molecule Adsorption and Nanoparticle Adhesion on the Surface of Thin Films

“…Photonics 2019, 6, x 2 of 18 be up to a few hundred nanometers, making it capable of the detection of bacteria or cells, for example [21,22]. However, the drawback of the method is that a relatively high film thickness (200-600 nm) is required to obtain the interference pattern [23][24][25][26][27][28], mainly in the case of FT-RIfS (Reflective Interferometric Fourier Transform Spectroscopy), where the sensing layer (substrate) is highly ordered nanoporous anodic aluminum oxide (AAO) with a layer thickness of a few micrometers [22,29,30]. By using high refractive index materials (e.g., SiN), the thickness of the sensing layer can be slightly reduced [31][32][33].…”

Room temperature ethanol sensor with sub-ppm detection limit: Improving the optical response by using mesoporous silica foam

“…Reflectometric interference spectroscopy [28,[31][32][33][34][35][36] is an optical method which is based on the spectral (red) shift of the interference pattern reflected from a (few hundred nanometers of layer thickness) thin film. The wavelength shift is caused by the adsorption or adhesion of molecules or colloidal units, so it can be utilized in antigen-antibody reactions or to detect the adsorption of volatile compounds [].…”

Correlational Analysis of Proteins and Nonmetallic Nanoparticles in a Deep-Nulling Microscope

“…17,18 SPR measures minute changes in the refractive index at surfaces that are covered with biomolecules such as antibodies. The method allows, for example, to measure binding of additional antibodies on the nanometer scale.…”

“…It is for these reasons that researchers deeply wish to have label-free detection technologies, a wish that resulted in the development of techniques such as surface plasmon resonance measurements (SPR). , SPR measures minute changes in the refractive index at surfaces that are covered with biomolecules such as antibodies. The method allows, for example, to measure binding of additional antibodies on the nanometer scale.…”