Spectrophotometric and adsorptive stripping square wave voltammetric determination of iron in olive oils, as complex with 5,5-dimethylcyclohexane-1,2,3-trione 1,2-dioxime 3-thiosemicarbazone (DCDT).

Abstract

Two methods for the determination of iron in olive oil by spectrophotometry and by adsorptive stripping square wave voltammetry (Ad-SSWV) have been developed. These two methods are based on the formation of a 5,5-dimethylcyclohexane-1,2,3-trione 1,2-dioxime 3-thiosemicarbazone (DCDT)-iron(II) complex in strongly acid media. In both, iron is extracted from the olive oil by using HCl. Spectrophotometric determination of iron with DCDT is based on the feature that the DCDT-Fe complex shows an absorbance maximum at 550 nm. A calibration graph has been constructed from 0 to 4000 ng mL(-)(1), and the detection limit was 115 ng mL(-)(1) (57 ng g(-)(1) in olive oil). On the other hand, the voltammetric determination of the metal is based on the appearance of a peak due to an adsorptive reductive process of the complex that it is observed when the Ad-SSWV technique is used. A calibration graph has been constructed from 0 to 30 ng mL(-)(1), and the detection limit was 0.55 ng mL(-)(1) (13.75 ng g(-)(1) in olive oil according to the proposed procedure).