[Determination of sodium iron (III) ethylenediaminetetraacetate in iron-fortified soy sauce by reversed-phase ion-pair high performance liquid chromatography].

A novel reversed-phase ion-pair high performance liquid chromatographic method was developed for separation and determination of sodium iron (III) ethylenediaminetetraacetate (NaFeEDTA) in iron-fortified soy sauce. Sample treatment and chromatographic conditions were investigated. After precipitation by methanol, the sample was separated on a Zorbax C8 column (150 mm x 4.6 mm i. d., 5 microm). The mobile phase was 12.5% (v/v) methanol solution containing 0.13% (v/v) tetrabutyl ammonium hydroxide and 0.052% (v/v) formic acid ( pH 3.5). NaFeEDTA was detected at 254 nm. The separation was achieved within 30 min with a flow rate of 1.00 mL/min. An iron-fortified soy sauce sample containing 2.00 g/L NaFeEDTA was analyzed for 6 times, and the relative standard deviation (RSD) of peak areas of NaFeEDTA was 0. 89%. The recoveries of NaFeEDTA ranged from 94.15% to 101.5% with the spiked amounts of 0.50 - 4.00 g/L. The detection limit of NaFeEDTA standard solution was 0.03 mg/L. This simple and rapid method with good reproducibility can be used for the determination of NaFeEDTA in iron-fortified soy sauce.