title: Analytical application of the complexation of Nb(V) with bromopyrogallol red in micellar media.
abstract: A spectrophotometric method for the détermination of trace amounts of Nb(V) based on the formation of a ternary complex with Bromopyrogallol Red (L) and cetylpyridinium bromide (CPB) in 1M hydrochloric acid/15% dimethylformamide medium has been developed. The ternary 1:2:2 Nb-L-CPB complex is formed. The absorbance maximum is at 645 nm, the molar absorptivity being (4.00 +/- 0.04) x 10(4) l.mole(-1).cm(-1). The relative standard deviation is 1.9% and Beer's law is obeyed up to 1.4 mug of Nb(V) per ml. The application of the method to the determination of Nb in pyrochlore-bearing rocks is described. A possible mechanism of interaction of the surfactant with the Nb-L complex is discussed.
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemistry, University of Oviedo, Oviedo, Spain.
authors.forename: M E
authors.initials: ME
authors.lastname: Garcia
authors.forename: A
authors.initials: A
authors.lastname: Sanz-Medel