4.5.2.4.   Quaternary Mixtures of Alcohols by the RIfS Array and the SPR Setup

Finally, quaternary mixtures of methanol, ethanol 1-propanol and 1-butanol were measured by the RIfS array setup and by the SPR setup to compare the performance of both setups [196]. A 4-level equidistant full factorial design with relative saturation pressures between 0 and 0.09 was measured for the calibration data set. The validation data set is a 3-level equidistant full factorial design with relative saturation pressures between 0.015 and 0.075. The data of the SPR setup, which was equipped with a 100 nm Makrolon layer, were recorded during 124 seconds of exposure analyte (40 time points) and afterwards for 806 seconds during exposure to synthetic air (116 time points). The sensor responses for different concentrations of the single analytes are shown in figure 24. The data of the array setup, which was equipped with a 95 nm and a 165 nm Makrolon layer and additionally with a PUT layer, were recorded during 236 seconds exposure to analyte (16 time points recorded per Makrolon layer) and afterwards during 3240 seconds of exposure to synthetic air (34 time points recorded per Makrolon layer).  The sensor signals of the PUT layer were recorded only once at 236 seconds as the swelling kinetics of this polymer cannot be differentiated at the chosen time resolution of the measurements.