Determination of Total Iron and Ferrous Contents in Brown Sugar by Triple-wavelength Spectrophotometry

Abstract:

Determination of the total iron content in foods by atomic absorption spectrometry (the national standard method used) requires ashing during pretreatment, which renders the entire operation tedious and time and energy consuming. Herein, a triple-wavelength spectrophotometric method was established for determining the iron content in brown sugar. Brown sugar solutions of known concentration were mixed with phenanthroline monohydrate and then measured by triple-wavelength spectrophotometry at wavelengths of 423, 510, and 700 nm. The total iron content was then calculated from the spectral data. Using this method, the recovery rate of total iron content in brown sugar was evaluated, as well as the content of ferrous iron in brown sugar solutions lacking the reducing agent. The results showed that this method can efficiently deduce the influence of the color agent and baseline drift. The content of total iron was (3.65±0.29) mg/kg, whereas that of ferrous iron was (13.29±0.18) mg/kg. The valence state of iron in brown sugar was mainly ferrous, accounting for more than 98%. The recovery rate of the total iron content was about 103%. This simple technique, which avoids the complicated processes of the traditionally used method, is suitable for industrial applications.