Abstract: | Using spectrophotometric methods, the protopysis constant of the 5.ClDMPAP reagent (pKa1 = −0.19; pKa2 = 1.97; pKa3 = 11.98) and the stability constant of its vanadic complex (6.0 ± 0.11) × 1014 were determined. A high-sensitivity spectrophotometric method was developed to determine V(V) using 0.1–1.2 ppm and pH = 3.8. ε586 = 55,300 ± 400 liters · mol−1 · cm−1. A study on the most important interferences and the way to eliminate them was carried out. The method can be applied to the determination of the element in steels and ferrovanadiums. |