2- Hydroxyacetophenonebenzoylhydrazone- a novel spectrophotometric reagent for the determination of traces of rare metals

This work describes the synthesis and characterization of a new spectrophotometric reagent, 2-hydroxyacetophenonebenzoylhydrazone (HAPBH) for the trace determination of rare metals (e.g. V, Mo, etc.). A very simple, ultra-sensitive and highly selective non-extractive spectrophotometric methods for the determination of trace amounts of vanadium(V) or molybdenum(VI) using HAPBH has been developed. 2-HydroxyacetophenonebenzoyIhydrazone (HAPBH) reacts in slightly acidic 50% aqueous 1,4-dioxane media with vanadium(V) or molybdenum(VI) to give a yellow or an orange chelate, which has an absorption maximum at 422nm or 443nm, respectively. The reaction is instantaneous and absorbance remains stable for 48h. The average molar absorption co-efficient was found to be 7.7 X 10/sup 4/ L mol/sup -1/ cm/sup -1/ of V or 2.59 x 10/sup 4/L mol/sup -1/ cm/sup -1/ of Mo, respectively. Linear calibration graphs were obtained for 0.1-15 or 0.1-30 mgL/sup -1/ of V or Mo, respectively. A large excess of over 50 cations, anions and some common complexing agents do not interfere in the determination. The method developed was used successfully in the determination of vanadium or molybdenum in several standard reference materials (alloys and steels) and complex synthetic mixtures. The method has high precision and accuracy (s= plus minus 0.01 for 0.5 mgL/sup -1/ of V or Mo). (author)