Silica-Based Room Temperature Phosphorescence Substrates: Wide Dynamic Ranges, Low Background, and Programmable Figures of Merit

The use of silica-based substrates for room temperature phosphorescence (RTP) was investigated. Contrary to reports in the literature, bare silica was shown to provide higher sensitivity (S/B) for RTP than filter paper when the specific surface areas of the two substrates were similar. The surface heterogeneity of bare silica resulted in nonlinear, discontinuous response curves for a model analyte, phenanthrene. However, analytically useful calibration curves were obtained on silica thin-layer phases in the presence of coadsorbed surfactant. The dynamic range on the silica substrate was 4 times greater and the background phosphorescence was 2 orders of magnitude lower than filter paper. The programming of figures of merit for silica-based substrates via the silica specific surface area is demonstrated.