Multisyringe flow injection analysis (MSFIA) for the automatic determination of total iron in wines

This work presents a multisyringe flow injection analysis (MSFIA) system for the automatic spectrophotometric determination of total iron in wine. The reaction is based on the complexation of Fe(II) with 2-(5-bromo-2-pyridylazo)-5-(diethylamino)-phenol (Br-PADAP). Ascorbic acid was used as reducing reagent for Fe(III) to Fe(II) and, in this way, to determine the total iron content in wine. The absorbance of the Fe(II)-(Br-PADAP)₂ complex was measured at 748 nm. The proposed method provided a working rage from 0.36 to 5 mg L^-1 of Fe(II), with a detection limit of 0.11 mg L^-1 of Fe(II), a relative standard deviation of 0.42% (3 mg L^-1 of Fe(II), n = 10), and a 46 h^-1 injection throughput. The system is very simple, rapid and selective, and has been successfully applied to determine total iron in red, rosé and white wine without any need for sample pre-treatment steps. The results agree well with ICP-AES, which used as a reference method.