Liquid Chromatographic Determination of Cobalt(II), Nickel(II) and Silver(I) using 6-Methyl-2-pyridine Carboxaldehyde Isonicotinoyl Hydrazone as Derivatizing Reagent

Abstract

The reagent 6-methyl-2-pyridine carboxaldehyde isonicotinoyl hydrazone reacts with copper(II), nickel(II), cobalt(II), iron(II), zinc(II), mercury(II) and silver(I) to develop color in aqueous methanolic media with maximum in pH range 4-5. The molar absorptivity was observed within 6.2 × 10³ to 3.9 × 10⁴ L·mol^-1cm^-1 within 335-372 nm. Cobalt(II), nickel(II) and silver(I) chelates separated from Kromasil 100, C-18, 10 μm (250 × 4.6 mm id) column, when eluted with methanol: water : acetonitrile : tetrabutyl ammonium bromide (1 mM) (53 : 25 : 20 : 2 v/v/v/v) with a flow rate 1 mL/min and UV detection at 256 nm. Linear calibration range for cobalt(II) and nickel(II) was 1-5 μg/mL, but for silver (I) it was (5-25) μg/mL. The detection limits for cobalt, nickel and silver were observed 80, 110, 400 ng/mL, respectively. The method was applied for the determination of cobalt and nickel from tea and tobacco leaves and silver from photographic film.