Experimental design methodologies to optimise the spectrofluorimetric determination of Losartan and Valsartan in human urine

A spectrofluorimetric method has been developed for the determination of tw o angiotensin II receptor antagonists (ARA II): Losartan and Valsartan. A f ractional factorial design and a central composite design were used. The ke y factors considered in the optimization process were pH, temperature and e mission slit width. Maximum fluorescent intensity was established as respon se for each experiment. The response surfaces confirmed the robustness of t he method. A clean-up procedure was used for urine samples that consisted o f a solid-phase extraction using Cs cartridges. The total analysis time was lower than 30 min. This method proved to be accurate (RE, 8%), precise (in tra- and inter-day coefficients of variation were lower than 8% and sensiti ve enough (LOQ c.a. 0.5 mug ml(-1)) to be applied to the determination of L osartan and Valsartan in urine samples. (C) 2001 Elsevier Science B.V. All rights reserved.