Flavonol derivatives for determination of Cr(III) and W(VI)

Simple, rapid, sensitive and selective methods for the determination of Cr( III) and W(VI) with flavonol derivatives in the presence of surface-active agents are proposed. In the pH ranges 3.4-4.2 and 1.9-2.5, the molar absorp tivities of Cr(III)-morin-emulsifier S (EFA) and W(VI)-morin-polyvinylpyrro lidone (PVP) systems are 1.13 x 10(5) and 2.13 x 10(4) L mol(-1) cm(-1) at 435 and 415 nm, respectively. The Cr(III) quercetin-PVP and W(VI)-quercetin -cetylpyridinium bromide (CPB) systems are formed in the pH ranges 4-4.6 an d 2.2-2.8 with molar absorptivities 1.02 x 10(5) and 9.02 x 10(4) L. mol(-1 ) cm(-1) at 441 and 419 nm, respectively. The linear dynamic ranges for the determination of Cr(III) and W(VI) with morin in the presence of EFA and P VP are 0.03-0.46 and 0.71-8.1 mug mL(-1), respectively, The corresponding r anges with quercetin are 0.04-0.54 and 0.14-2.1 mug mL(-1) of Cr(III) and W (VI), respectively. The r.s.d (n = 10) for the determination of 0.25 and 3. 7 mug mL(-1) of Cr(III) and W(VI) with morin and their detection limits are 0.88 and 0.99% and 0.016 and 0.63 mug mL(-1\), respectively. Using quercet in, the r.s.d (n = 10) for 0.22 and 1.2 mug mL(-1) of Cr(III) and W(VI) and their detection limits are 0.92 and 0.91% and 0.015 and 0.08 mug mL(-1), r espectively. The critical evaluation of the proposed methods is performed b y statistical analysis of the experimental data, The proposed methods are a pplied to determine Cr in steel, non-ferrous alloys, wastewater and mud fil trate and to the determination of W in steel.