Simple and selective spectrophotometric determination of ruthenium after solid phase extraction with some quinoxaline dyes into microcrystalline p-dichlorobenzene

A simple selective and highly sensitive extraction method has been developed for the determination of ruthenium spectrophotometrically after extraction of its 2,3-dichloro-6-(3-carboxy-2-hydroxy-1-naphthylazo)quinoxaline (I), 2,3-dichloro-6-(2-hydroxy-3,5-dinitrophenylazo)quinoxaline (II) and 2,3-dichloro-6-(2,7-dihydroxy-naphthylazo)quinoxaline (III) complexes into microcrystalline p-dichlorobenzene. The optimization of experimental conditions for the procedure is studied. The solid p-dichlorobenzene containing the ruthenium-reagent (I-III) complexes is separated by filtration and dissolved in N,N-dimethylformamide. The absorbance is measured at lambda(max) 622, 518 and 542 nm against reagents I, II and III, respectively, as blank. Beer's law is obeyed upto 2.5 mug ml(-1) of ruthenium. The molar absorptivity, Sandell sensitivity, detection and quantification limits are calculated, when compared with those parameters without using solid phase extraction method. The interference of various ions has been studied in detail and the statistical evaluation of the experimental results is reported. The proposed methods have been successfully applied for the determination of trace amount of ruthenium in seawater, ore and metallurgy products. (C) 2002 Published by Elsevier Science B.V.