Spectrophotometric determination of aluminium with 2,3,7-trihydroxy-9-[4-(2,4-dihydroxy)phenylazo] phenylfluorone

Abstract

The conditions of color reaction of Aluminium(III) with a new organic reagent 2,3,7-trihydroxy-9-[2,4-dihydroxy)phenylazo] phenylfluorone (ARPF) in the presence of cetyltrimethyammonium bromide (CTMAB) were studied. It was found that Aluminium(III) reacts with ARPF and CTMAB in pH 6.5 HAc-NaAc buffer solution to form a 1∶2 red complex with maximum absorption at 562 nm. The molar absorptivity is 1.10×105 L·mol−1·cm−1. Beer’s law is obeyed in the range of 0–5.5 μg Al(III) per 25 mL. The method has been applied to determination of Aluminium in the limestone with satisfactory results.