A spectrophotometric determination of V(V) with 2-hydroxy-1-naphthaldehy-de guanylhydrazone can be performed in a concentration range varying from 0.70–8.70 ppm of vanadium; the molar absorptivity is 7.7 ×l03 litres mol−1 cm−1 at 405 nm and the relative error is ±0.60. The stoichiometry (1: 1) of the complex was established by different methods. This method of spectrophotometric determination has been applied satisfactorily to the determination of vanadium in steel.
