Derivative Spectrophotometry Determination of Cobalt(II)with 1-(2 PyridyIazo)-2-Naphthol in Micellar Medium

摘要

A spectrophotometeric and first derivative spectrophotometeric determination of cobalt(II)is carried out with 1-(2 pyridylazo)-2-naphthol as complexing reagent in aqueous phase using non-ionic surfactant Tween 80.The cobalt is determined in the range 1.7-225 ng ml~(-1)with detection limit(2a)of 1.7 ng ml~(-1)The molar absorptivity and Sandell's sensitivity are 0.87 X(10~4 mol~(-1)cm~(-1))and 6.8 ngcm~(-2)at 580 nm.The optimum pH of the complex is 5.The critical micelle concentration(cmc)of Tween 80 is 5 %.Absorption studies in the first derivative mode is carried out to determine the absorption maximum of the complex and to overcome interference due to the presence of certain metal ions.The present method is compared with that of AAS and no significant difference is noted between the two methods at 95% confidence level.The method has been applied for the determination of Co(II)in pharmaceutical samples.