4.5.2.3.   Methanol, Ethanol and Propanol by the RIfS Array and the 4l Setup

Ternary mixtures of methanol, ethanol and 1-propanol were measured by the RIfS Array setup and the 4l setup to compare the performance of these setups [195]. Additionally the effect of smoothing the sensor responses is investigated, as the sensor signals of the RIfS setups are noisier than the sensor signals of the SPR setup using Makrolon as sensitive layer. For both setups, a 6-level equidistant full factorial design with relative saturation pressures between 0 and 0.1 was measured twice for the calibration data set. The validation data set is a 5-level equidistant full factorial design with relative saturation pressures between 0.01 and 0.09 also measured twice. The data of the 4l setup, which was equipped with a 310 nm Makrolon layer, were recorded during 180 seconds of exposure to analyte (44 time points recorded) and afterwards 575 seconds during exposure to synthetic air (149 time points recorded). The data set of the array setup, which was equipped with a 80 nm, a 120 nm, and a 160 nm Makrolon layer and additionally with a PUT layer, were recorded during 240 seconds exposure to analyte and afterwards during 210 seconds of exposure to synthetic air with a time resolution of 50 data points per sensor. Due to a bug in the program for the gas mixing station, 15 measurements of the calibration set and 18 measurements of the validation sets had to be removed.