Complexation equilibria between niobium(V) and 4-(4′H-1′,2′,4′-triazolyl-3′-azo)-2-methylresorcinol. Extraction-spectrophotometric determination of niobium in pyrochlore-bearing rocks

1. Sánchez, Ma.J.
2. Francisco, A.
3. Jiménez, F.
4. Montelongo, F.G.