Simplification of iron speciation in wine samples: A spectrophotometric approach.

Abstract

A simple direct spectrophotometric method has been developed for analysis of Fe(II) and total Fe, in wine samples. This method is based on the formation of an Fe(II) complex with 2,2´-dipyridylketone picolinoylhydrazone (DPKPH), which shows a maximum green-blue absorption (l=700 nm) at pH 4.9. Operative conditions for the batch procedure were investigated including reagent concentration, buffer solutions and wavelength used for the spectrophotometric detection. The tolerance limits of foreign ions and sample matrix have been also evaluated. Limits of detection and quantification were 0.005 mg L-1 and 0.017 mg L-1 of Fe(II) respectively, allowing its determination in real wine samples. Finally, the proposed method was used in the analysis of a series of white, rose and red wines. Results were compared with those obtained by the reference method Commission Regulation (ECC) No 2676/90 of September 1990 determining Community methods for the analysis of wines for Fe analysis, showing the reliability of the spectrophotometric determination of Fe with DPKPH in wine samples.