DETERMINATION OF TRACE AMOUNTS OF VANADIUM IN NATURAL-WATERS AND COAL FLY-ASH WITH 2-(8-QUINOLYLAZO)-5-(DIMETHYLAMINO)PHENOL BY REVERSED-PHASE LIQUID CHROMATOGRAPHY-SPECTROPHOTOMETRY

In reversed-phase high-performance liquid chromatography (RP-HPLC) for neutral and cationic metal chelates with azo dyes, tetraalkylammonium salts (TAASs) are added to an aqueous organic mobile phase. The TAASs are dynamically coated on the reversed stationary support. As a result of the addition of TAAS, the retention of the chelates is remarkably reduced. Tetrabutylammonium bromide permits rapid separation and sensitive spectrophotometric detection of the vanadium(V) chelate with 2-(8-qulnolylazo)-5-(dimethylamlno)-phenol, making It possible to determine trace vanadium(V). When a 100-mm3 aqueous sample was Injected, sensitivity and precision were as follows: peak height calibration curves of vanadium(V) were linear up to 800 pg at 0.005 absorbance unit full scale (AUFS) and up to 160 pg at 0.001 AUFS; the relative standard deviation for 10 determinations at 0.005 AUFS was 2.3% at a level of 320 pg of vanadium(V); the detection limit was 2.6 pg at 0.001 AUFS. Many cations including iron(III) and aluminum(III) do not Interfere with the determination. Vanadium in coal fly ash and natural waters can be successfully determined without preseparation and preconcentration of vanadium. © 1990, American Chemical Society. All rights reserved.