Abstract: Soya-bean flour extracts were subjected to gel-permeation chromatography on Fractogel TSK HW 50 before determination of Fe, Zn and organic functional groups. A continuous-flow system was used with an appropriate spectrophotometric reagent, e.g., Ferrospectral {disodium 4,4'-[3-(2-pyridyl)-1,2,4-triazine-5,6-diyl]bis(benzenesulfonate)} and zincon for Fe and Zn, respectively. The results showed that a significant amount of the Fe was bound to carboxylic and phenolic organic compounds whereas only small amounts of Zn were bound to organic compounds, i.e., phenols and aromatic amines and thiols. Information about the relative amounts of free, labile and stable Fe species and of cationic, anionic and neutral Fe complexes was obtained by shaking aqueous wheat flour extracts with different ion exchangers, e.g., Sepharose CL 6B and Sephadex, followed by photometric determination of the Fe remaining in solution The method is also suitable for analyzing aqueous extracts from other foods.

Abstract: A flow injection-CCD diode array detection spectrophotometry with partial least squares (PLS) program for simultaneous determination of iron, copper and cobalt in food samples has been established. The method was based on the chromogenic reaction of the three metal ions and 2- (5-Bromo-2-pyridylazo)-5-diethylaminophenol, 5-Br-PADAP in acetic acid - sodium acetate buffer solution (pH5) with Triton X-100 and ascorbic acid. The overlapped spectra of the colored complexes were collected by charge-coupled device (CCD) - diode array detector and the multi-wavelength absorbance data was processed using partial least squares (PLS) algorithm. Optimum reaction conditions and parameters of flow injection analysis were investigated. The samples of tea, sesame, laver, millet, cornmeal, mung bean and soybean powder were determined by the proposed method. The average recoveries of spiked samples were 91.80%~100.9% for Iron, 92.50%~108.0% for Copper, 93.00%~110.5% for Cobalt, respectively with relative standard deviation (R.S.D) of 1.1%~12.1%. The sampling rate is 45 samples h-1. The determination results of the food samples were in good agreement between the proposed method and ICP-AES.