Uncertainties associated with signal measurements from solutions and from solid substrates using luminescence based methods

A careful study was performed to evaluate and compare uncertainties associated with the measurement of luminescence from chrysene by using fluorimetry in solution and by using solid surface room-temperature phosphorimetry (SSRTP). Chrysene was chosen as the luminescent analyte (measurand) for this study because it is a substance of environmental interest and also because it presents strong natural fluorescence and phosphorescence that is easily induced by the external heavy atom effect. The most common approach for uncertainty calculation is the one indicated in the Guide to the Expression of Uncertainty in Measurement which is recognized worldwide. The most relevant sources of uncertainty were identified. The expanded uncertainty (k = 2; 95%) for SSRTP was 3.27 x 10... mol L... (3.7 ng of chrysene) with relevant contributions from the internal reproducibility, preparation of solutions and from the analytical curve. This value is equivalent to 28% of the reference analyte value. For fluorimetry, an acceptable value for the expanded uncertainty was achieved by preparing solutions by weighing masses of analyte and solvent. In this case, the huge contribution from the preparation of solutions by adjusting volume is minimized and the uncertainty magnitude was 2.12 x 10... mol L... (21.2% of the chrysene reference concentration). In this case, relevant contributions were from the repeatability, the internal reproducibility and from the analytical curve. The preparation of solutions by weighing does not have a relevant impact in improving the quality of the signal measurements by SSRTP. (ProQuest: ... denotes formulae/symbols omitted.)