4.5.2.1.   Methanol and Ethanol by the SPR Setup

 An about 300 nm thick Makrolon layer was coated on the glass prism of the SPR setup. Further details of the experimental setup can be found in [190]. In addition to several single analyte measurements, 2 datasets were recorded for a multicomponent analysis [191]. The calibration data set is a 9-level full factorial design whereby the relative saturation pressures (p_i/p_i0) of methanol and ethanol were varied between 0 and 0.045. The validation data set is an 8-level full factorial design with relative saturation pressures between 0.0025 and 0.0425. 24 measurements were identified as outliers according to [192], whereby 20 measurements of the calibration set and 4 measurements of the test set were removed. These measurements showed outlying high signals and were recorded in series. During all measurements, the polycarbonate was exposed to the analyte mixtures for 120 s and after that to synthetic air during 300 s. During the exposure to analyte the data were recorded every 5 s and during the exposure to synthetic air with a time resolution of 10 s resulting in 53 time points (see also figure 15).