Double injection/single detection asymmetric flow injection manifold for spectrophotometric determination of ascorbic acid and uric acid: Selection the optimal conditions by MCDM approach based on different criteria weighting methods

A simple and sensitive double injection/single detector flow injection analysis (FIA) method is proposed for the simultaneous kinetic determination of ascorbic acid (AA) and uric add (UA). This method is based upon the difference between the rates of the AA and UA reactions with Fe3+ in the presence of 1, 10-phenanthroline (phen). The absorbance of Fe2+/1, 10-phenanthroline (Fe-phen) complex obtained as the product was measured spectrophotometrically at 510 nm. To reach a good accuracy in the differential kinetic determination via the mathematical manipulations of the transient signals, different criteria were considered in the selection of the optimum conditions. The multi criteria decision making (MCDM) approach was applied for the selection of the optimum conditions. The importance weights of the evaluation criteria were determined using the analytic hierarchy process, entropy method, and compromised weighting (CW). The experimental conditions (alternatives) were ranked by the technique for order preference by similarity to an ideal solution. Under the selected optimum conditions, the obtained analytical signals were linear in the ranges of 0.50-5.00 and 0.50-4.00 mg L-1 for AA and UA, respectively. The 3 sigma detection limits were 0.07 mg L-1 for AA and 0.12 mg L-1 for UA. The relative standard deviations for four replicate determinations of AA and UA were 2.03% and 3.30% respectively. The method was also applied for the analysis of analytes in the blood serum, Vitamine C tablets, and tap water with satisfactory results. (C) 2016 Published by Elsevier B.V.