Determination of Arsenic in Soil Alkali by Graphite Furnace Atomic Absorption Spectrophotometery Using Modified Corn Silk Fiber as Adsorbent

A safe, rapid, simple and environmentally friendly method based modified corn silk fiber (MC), chemical modified with succinic anhydride (C4H4O3), was developed for the extraction and preconcentration of As(III) in food additives soil alkali sample prior to graphite furnace atomic absorption spectrometry (GFAAS) analysis. The structure and properties of VC (unmodified corn silk fiber) and MC were analyzed and discussed by means of FTIR, SEM and TG, and the effect of adsorbent amount, pH, soil alkali solution concentration, adsorption time and adsorption temperature were carefully optimized. Under the optimum conditions, the relative standard deviations (RSD, n=6) were1.27-3.05%, the calibration graph was linear in the range of 0-100ug/L and the limits of detection (LOD) was 0.13 mu g/L. The surface of MC became loose and porous which increased the adsorption area. Comparing with VC, carboxy groups were measured in MC and the increase of negative electron group in fiber molecular made its coordination combining ability with As(III) enhanced; In comparison with the removal arsenic rate of VC, MC's significantly increased by 2.86 fold. The recovery rate of soil alkali, treated by VC and MC, reached to 96.85% and 94.32%, and it did not affected the function of soil alkali.