STUDY ON 4,5-DIBROMO-O-NITROPHENYLFLUORONE FOR THE SPECTROPHOTOMETRIC DETERMINATION OF MICRO AMOUNTS OF TANTALUM IN THE PRESENCE OF LARGE AMOUNTS OF NIOBIUM
Micro amounts of tantalum can be directly determined with 4,5-dibromo-o-nitrophenyl-fluorone-citric acid and TritonX-100 in 0.5—5M sulfuric acid.Under the experimental conditions employed, the molar component ratios of Ta:Br ONPF:citric acid are 1:2:1. The apparent molar absorptivity of Ta at 53O nm is 1.76×10~5 L·mol~(-1).cm~(-1) and Beer's law is obeyed for 0—10μg of Ta in 25 ml at 530 nm. Optimum systems for masking niobium have been studied with a mixture of oxalic acid and hydrogen peroxide and about 1...