SEPARATION OF METAL-CATIONS IN ACIDIC SOLUTION BY CAPILLARY ELECTROPHORESIS WITH DIRECT AND INDIRECT UV DETECTION

Methods for the detection of metal cations under acidic conditions, ne ar pH 2, in capillary electrophoresis (CE) were investigated, Conditio ns for direct UV detection of UV absorbing metal cations such as Cr3+, Cu2+, Fe3+, UO22+, VO2+, and VO2+ were established with aqueous HCl o r HClO4 as the electrolyte carrier, The speciation of vanadium(IV) and vanadium(V) at pH 2.3 by CE was achieved with direct detection at 185 nm, With the strong absorbance at 185 nm, no complexation was needed to detect the metal cations, An indirect UV detection scheme for acidi c conditions was also investigated. Several background carrier electro lytes (BCES) were studied including 4-methylbenzylamine nicotinamide, pyridazine, guanidine, 3-picoline, and chromium(III) to determine thei r effectiveness under very acidic conditions, The effect of ionic surf actants and the nonionic surfactant, Triton X-100, on the peak heights and N values was also studied.