Solvent extraction-spectrophotometric determination of trace amounts of ammonium, barium and potassium in a mixture by dicyclohexyl-18-crown-6 and orange II.

A simple and sensitive extraction-spectrophotometric method for the determination of ammonium, barium and potassium in a mixture solution is reported. The DC18C6-ammonium-Orange II (DC18C6-NH(4)-OR II), DC18C6-Barium-Orange II (DC18C6-Ba-(OR II)(2)) and DC18C6-Potassium-Orange II (DC18C6-K-OR II) ternary complexes are quantitatively extracted into dichloromethane and their absorbances are measured at 483 nm. Linear calibration graphs were obtained over the concentration ranges of 0.05-3.00, 0.05-2.00 and 0.05-6.00 mug ml(-1) for ammonium, barium and potassium, respectively. The relative standard deviations for 1.0 mug ml(-1) of ammonium, barium and potassium are, respectively, 1.1, 1.6 and 2.50%. The limit of detection, LOD, for these three ions is reported to be 0.02, 0.01 and 0.02 mug ml(-1), respectively. The interfering effect of a large number of diverse ions on the determination of these three ions was studied. The method was applied to the Karon river raw water contaminated with industrial and house sewages. The results showed high potential of the recommended method for the determination of NH(4)(+), Ba(2+) and K(+) in water samples.