USE OF A SURFACTANT IN THE SPECTROPHOTOMETRY DETERMINATION OF TRACE AMOUNTS OF NICKEL

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Date
1992-04
Authors
THERESA, AWUSOLA ADAMMA
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Abstract
The procedure used in establishing a sensitive spectrophotometric method for the determination of nickel in trace level is described. The method involves the use of a long chain quaternary ammonium salt, cetyltrimethylammonium bromide as a surfactant and Xylenol orange as an indicator. To arrive at the method, first the optimum conditions for the interaction between the cetyltrimethylammonium bromide (CTAB), xylenol orange (XO) and metal ions were established. Then the nickel complex Ni-XO-CTAB was chosen for further study. The conditions for the increased absorbance of the nickel complex were established by observing the U.V. absorbance of the complex. The results show that the Xylenol orange (XO) and cetyltrimethylammonium bromide (CTAB) interact at pH 10.5 to form stable systems having X0:CTAB mole ratios of 1:2 and 1:6. The formulae of the systems should be [x0 {CTAB)2] n and [X0(CTAB)6] n where n is an interger. The nickel complex was found to have a maximum absorbance at 622 nm with a molar extinction coefficient of 6.14 x 104 i. mole-1 cm1' The composition of the nickel complex was studied using the mole ratio method. The mole ratio of Ni:XO in the complex was found to be 1:4. The formula of the nickel complex should then be Ni [XO (CTABT)2]4 and Ni[XO (CTAB)6]4 for the two established XO: CTAB systems. The selectivity of the method was studied by observing the absorbance of nickel complex of known concentration of nickel in pure nickel solution and in the presence of some other metal ions. This study reveals that the selectivity of the method is limited due to interference from ion, cadmium and cobalt ions. No attempt was made in this study to mask the interfering ions.
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A Thesis presented to the Ahmadu Bello University in Partial fulfilment for the degree of MASTER OF SCIENCE ANALYTICAL CHEMISTRY THERESA AWUSOLA ADAMMA ABU B.Sc. (Nigeria); P.GD.E(A.BU), C. A.T.D.E.( London) A PRIL 1982
Keywords
USE,, SURFACTANT,, SPECTROPHOTOMETRY,, DETERMINATION,, TRACE,, AMOUNTS,, NICKEL..
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