Solvent sublation using 8-hydroxyquinoline as a ligand for determination of trace elements in water samples

Solvent sublation was studied to separate and pre-concentrate a trace of Co(II), Cu(II) and Ni(II) as 8-hydroxy quinoline (oxine, HQ) complexes for their determination. The experimental conditions such as pH of solution, amount of HQ as a ligand and stirring time were investigated to optimize complex formation. Amount of surfactant and type of solvent were optimized for efficient sublation. The analyte ions in a 1.0 l sample were formed as metal-oxine complexes by the addition of 1.2% HQ 10 mi to the solution of pH 9.0 adjusted with NaOH solution. The solution was stirred for 30 min with a mechanical stirrer. Then 4 mi of 0.4% cetyltrimethylammonium bromide (CTAB) was added to the solution. After the solution was stirred for a further 20 min, it was transferred to a flotation cell and the complexes were floated by bubbling a nitrogen gas and extracted into 25 mi of methylisobutyl ketone (MIBK) on the surface of the aqueous solution. The analytes in the organic phase were determined by graphite furnace atomic absorption spectrophotometry (GF-AAS). This sublation method was applied to real samples and recoveries of 84-120% were obtained in the spiked samples. (C) 2001 Elsevier Science B.V. All rights reserved.