ZERO-ORDER AND 1ST-DERIVATIVE SPECTROPHOTOMETRIC DETERMINATION OF TRACE AMOUNTS OF RUTHENIUM AFTER EXTRACTION OF ITS ION ASSOCIATION COMPLEX WITH 2,4,6-TRIS(2'-PYRIDYL)-1,3,5-TRIAZINE AND PICRATE

A solvent extraction-spectrophotometric determination of trace amounts of ruthenium has been developed, based on the formation of an ion association complex of ruthenium (III) with 2,4,6-tris(2'-pyridyl)-1,3,5-triazine as primary ligand and Picrate as counter-ion; this complex is then extracted into 1,2-dichloroethane. The complex is formed at pH 2.0-7.0, upon heating at 90-degrees-C for 60 min, and the ruthenium concentration can be determined by measuring the absorbance directly in the organic phase. Beer's law is obeyed over the concentration range 1.0-10.0 mug ml-1 corresponding to 0.050-0.500 mug ml-1 of ruthenium in the aqueous solution. The apparent molar absorptivity and the Sandell's sensitivity were found to be 3.4 . 10(5) l mol-1 cm-1 and 0.30 ng cm-2, respectively. The interference of various ions was examined and the serious interferences from iron and other metals of the VIII group were minimized by employing the derivative spectrophotometric technique in conjunction with appropriate masking agents.