New organic reagents for the photometric determination of Ba, Sr, Ca, and SO 4 2?

Abstract

1. Eleven bis-azo derivatives of chromotropic acid, containing a COOH group in the o-position to the azo group in one of the benzene rings and NO2, SO3H, AsO3H2, COOH, CH3, Cl, and OCH3 groups in the m- and p-position to the azo group, were studied as reagents for Ca, Sr, Ba, and sulfates. 2. Most of the compounds considered are highly sensitive reagents for Sr, Ba, and sulfates. 3. The possibility of a photometric determination of Sr, Ba, and SO42− with a reagent containing a NO2 group in the p-position to the azo group, i.e., carboxynitrazo, was demonstrated.