Column chromatographic preconcentration of cobalt and zinc with 3-hydroxy-4-imino-(N-2 '-pyridyl)-2-methylnaphthalen-1-one adsorbed on naphthalene and their estimation in vitamin and milk samples

A sensitive, economical and rapid spectrophotometric method of preconcentra tion and separation of cobalt and zinc has been developed using a solid che lating resin, 3-hydroxy-4-imino-(N-2'-pyridyl)-2-methylnaphthalen-1-one (HI PMN) supported on naphthalene. Co and Zn are quantitatively determined usin g this absorbent in a column in the pH range of 4.0-6.0 and 5.8-8.0 respect ively with a flow rate of 2 ml min(-1) The metal complex and naphthalene ar e dissolved out from the column with 10 ml of DMF and the absorbance is mea sured at 568.5 nm and 466 nm for Co and Zn, respectively. Beer's law is obe yed up to 15 mg l(-1), for Co and 22 mg l(-1) for Zn using this method with a sensitivity of 0.035 mug cm(-2) for Co and 0.032 mug cm(-2) for Zn for l og (I-0/I) = 0.001. Atomic absorption spectrometry cm (AAS) is also used to determine the metal ion concentration.