SPECTROPHOTOMETRIC DETERMINATION OF TRACE AMOUNTS OF COBALT WITH 2-HYDROXYBENZALDEHYDE-5-NITRO-PYRIDYLHYDRAZONE IN PRESENCE OF SURFACTANT AFTER SEPARATION WITH AMBERLITE IRC-718 RESIN

2-Hydroxybenzaldehyde-5-nitro-pyridylhydrazone (2HB-5NPH) was synthesi zed and its application in the spectrophotometric determination of met al ions was studied in the presence of surfactants. A separation proce dure. using a short column filled with Amberlite IRC 718, is proposed for the spectrophotometric determination of traces of cobalt. The infl uence of several ions, as interference, was discussed. The procedure w as applied to determination of cobalt in mixture sample with satisfact ory results (greater than or equal to recovery 96%; relative error les s than or equal to 2%; relative standard deviation less than or equal to 1.2% in the concentration range of 0.02-2.0 mg l(-1); detection lim it, 0.01 mg l(-1) in solution). Control of the pH during the column op eration is essential because the adsorption capacities are very sensit ive to change in pH. Their separation was carried out in 0.005 M Malic acid, 1.5 M HCl, 2.0 M HNO3, media. (C) 1998 Elsevier Science B.V. Al l rights reserved.