REVERSED-PHASE ION-PAIR HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC DETERMINATION OF -BENZOTHIAZOLYLAZO)-5-(3-SULFORPROPYL)AMINOPHENOL, -BENZOTHIAZOLYLAZO)-5-(3-SULFORPROPYL)AMINOPHENOL, 2-BENZOTHIAZOLYLAZO)-5-(3-SULFORPROPYL)AMINOPHENOL AND 2-BENZOTHIAZOLYLAZO)-5-(3-SULFORPROPYL)AMINOPHENOL CHELATES

The separation and determination of Co(III), Ni(II), V(V) and Fe(III) chelates with (2-benzathiazolylazo)-5-(3-sulfopropyl)aminophenol (BTAS PAP) by reversed-phase ion-pair HPLC was investigated. In the presence of the oxidant potassium iodate, BTASPAP reacts with Co(III), Ni(II), V(V) and Fe(III) to form stable, negatively charged, water-soluble ch elates. The chelates were separated on a C-18 siloxane bonded phase an d eluted within 7 min with acetonitrile-acetate-water (36:1:63 v/v) co ntaining 0.2 mol l(-1) acetic acid-sodium acetate buffer (pH 3.0) and 1.0 mmol l(-1) tetrabutylammonium bromide. The detection limits of Co( III), Ni(II), V(V) and Fe(III) at 565 nm are 0.3, 0.8, 0.3 and 1.0 ng (signal-to-noise ratio = 2), respectively. The method was applied to t he determination of Co, Ni, V and Fe in four samples of standard alloy s. (C) 1997 Elsevier Science B.V.