title: A highly selective spectrophotometric determination of niobium (V) using 3-hydroxy-2-[1'-phenyl-3'-(p-chlorophenyl)-4'-pyrazolyl]-4-oxo-4H-1-benzopyran as a complexing agent.
abstract: 3-Hydroxy-2-[1'-phenyl-3'-(p-chlorophenyl)-4'-pyrazolyl]-4-oxo-4H-1benzopyran (HPCPB) is used as an analytical reagent for the spectrophotometric determination of niobium in trace amounts with which it forms a yellow coloured complex (4:1) in perchloric acid medium. The complex is extractable into chloroform and shows absorption maximum at 407-418 nm with a molar absorptivity of 2.79 x 10(4) L mol(-1) cm(-1) and Sandell's sensitivity equal to 0.0033 microg Nb(V) cm(-2), respectively. Beer's law holds good in the range 0-1.2 microg Nb ml(-1), with a standard deviation of +/- 0.0015 absorbance units. The method is free from the interference of a large number of elements and handles satisfactorily the analysis of various samples of varying complexity.
authors.affiliation: Department of Chemistry, Kurukshetra University, Haryana, India.
authors.forename: Nivedita
authors.initials: N
authors.lastname: Agnihotri
authors.forename: Raj
authors.initials: R
authors.lastname: Kamal
authors.forename: Jaswant R
authors.initials: JR
authors.lastname: Mehta
mesh_terms: D000042:Absorption; D004785:Environmental Pollutants / Q000032:analysis*; D005419:Flavonoids / Q000737:chemistry*; D009556:Niobium / Q000032:analysis* / Q000737:chemistry; D010472:Perchlorates / Q000737:chemistry; D012680:Sensitivity and Specificity; D013053:Spectrophotometry / Q000379:methods; D013997:Time Factors
chemical_list: D004785:Environmental Pollutants; D005419:Flavonoids; D010472:Perchlorates; D009556:Niobium; C041477:3-hydroxyflavone