Use of the Alizarine Violet N (AVN) as a spectrophotometric reagent for aluminium determination.

The present work proposes the application of the 4-Hidroxy-3-(2-hydroxynaphtylazo)-benzenesulphonic acid (C.I. 15670), Alizarine Violet N (AVN), as a reagent for direct aluminium determination using molecular absorption spectrophotometry in the presence of tensoatives. Al(III) cation reacts with AVN in pH 9.4, forming a red complex, stable for at least 24 hours, with absorption minimum at 607nm and, against a reagent blank, (epsilon(complex) - epsilon(reagent)) = - 2.71 x 10(4) L.mol(-1).cm(-1). The reaction occurs in the presence of a Triton-X100 and CTAB tensoatives mixture, in the presence of EDTA, Al(III) determination is possible in the linear range of 50 up to 400ng.mL(-1), with a detection limit of 41 ng.mL(-1).