MULTIVARIATE OPTIMIZATION AIMING THE DEVELOPMENT AND VALIDATION OF A SELECTIVE ROOM-TEMPERATURE PHOSPHORIMETRIC METHOD FOR THE DETERMINATION OF CHRYSENE

摘要

In this work, a factorial design was applied for the development and validation of a solid surface roomtemperature phosphorimetric method aiming the selective determination of chrysene. Data analysis was made using several strategies: statistical experimental analysis (testing the significance of the factors using the analysis of variation, F-test and t-test), graphic method (Pareto's chart) and the evaluation of the interactions among all variables. This procedure aimed the achievement of high accuracy of results and minimization of the time spent for optimization. A statistical program was used as a supporting tool. As the result, the experimental conditions selected for the determination of chrysene were: use of silver (I) as the selective phosphorescence inducer (applied as single 5 (mu)L spike of Ag+ solution in the concentration range between 0,03 and 0,05 mol L-1); Basic pH of the analyte solution (NaOH 0,002 mol L-1); use of SDS as the substrate surface modifier (employed as single 5 (mu)L of a SDS (Sodium Dodecyl Sulphate) solution between 0,25 and 0,50 mol L-1). The optimized method is highly selective towards the presence of pyrene and allowing the detection of an effective mass of chrysene in the ng range (based on the absolute limit detection, ALOD).