Simultaneous extraction-spectrophotometric determination of trace amounts of barium and potassium by 18-crown-6 and Orange II

A simple and sensitive extraction-spectrophotometric method for the determi nation of barium and potassium is reported. The 18C6-Barium-Orange II (18C6 -Ba-(ORII)(2)) and 18C6-Potassium-Orange II (18C6-R-OR II) ternary complexe s are quantitatively extracted into dichloromethane and their absorbances a re measured at 483 nm. Linear calibration graphs were obtained over the bar ium concentration range of 0.1-5 mu g ml(-1) and potassium concentration ra nge of 1-8 mu g ml(-1). The relative standard deviations for 2.0 mu g ml(-1 ) barium and potassium are, respectively, 4.16% and 3.60%. The interfering effect of a large number of diverse ions on the determination of barium and potassium was studied. The method was applied to a synthetic sample with n atural matrix effects of tap water and the results showed high potential of the recommended method for the determination of Ba and K in water samples.