Spectrophotometric determination of lead in environmental and biological samples by flow injection microcolumn preconcentration and separation using DBMCSA chromogenic agent

The synthesis and purification procedure of dibromo-p-methyl-chlorosulphonazo (DBMCSA) chromogenic agent have been described. This agent was used for spectrophotometric determination of lead. In 0.16 mol L-1 nitric acid solution lead reacts with DBMCSA to form a 1:2 blue-coloured complex of maximum absorbance at 633 rim. Under the optimum conditions Beer's law was obeyed over Pb(II) concentration range 0-1.2 mu g mL(-1) and the apparent molar absorptivity was 9.48 x 10(4) L mol(-1) cm(-1). Detection limit and variation coefficient were found to be 2.4 ng mL(-1) and 1.2%, respectively. No interferences from the selected foreign ions were observed except for Sr(II), Ca(II) and Ba(II). However, these interferences were easily eliminated by sorption and separation using microcolumn packed with cigarette filter. The developed method was applied to the determination of lead in environmental and biological samples.