Study On Preconcentration Heavy Metal Ions Uing Cysteine Modified Silica Gel

In recent years, with the development of standard of living and the further cognition to the toxic and hazardous substances in food, people pay much more attention on food quality and safety. They can be bioaccumulated and pollute the environment, then threat to human health. So, it is very important to detect heavy metals in food. However, heavy metals in water and biological samples are usually low-concentration and variety, it is difficult to analyze by traditional methods. Therefore, a procedure for preconcentration and separation of heavy metals from samples is necessary.Based on solid phase extraction (SPE) and inductively coupled plasma mass (ICP-MS) technology, a rapid and sensitive method for the detection of heavy metal content in the food was developed. Using silica gel as support material, a kid of L-cysteine functioned silica gel has been designed and synthesized as a solid-phase adsorbent material for the adsorption of V (51), Cr (53), Cu (63), As (75), Cd (111) and Pb (208) in water and biological samples. The synthetic material was characterized by infrared spectroscopy and elemental analysis.The parameters such as the solution pH, sample flow rate, eluent type and concentration, which affect efficency of L-cysteine functioned silicon gel to V, Cr, Cu, As, Cd and Pb have been optimized in this paper. With enriched 30mL of 1.0μg L-1 of Cr, Cu, As, Cd and Pb from the mixed standard solution, a sample rate of 1.0 mL min-1 and the sorbent metals quantitatively eluted by 3.0 mL of 0.5 mol L-1 HNO3, obtain a better separation and enrichment effect. No interference from K (Ⅰ), Na (Ⅰ), Ca (Ⅱ), Mg (Ⅱ), Al (Ⅲ), Fe (Ⅲ), Ni (Ⅱ), Mn (Ⅱ), Co (Ⅱ), Ag (Ⅱ) and Hg (Ⅱ) at 10,10,5,5,1,1,2,2,2,0.5 and 0.5 mg L-1 was observed. The relative standard deviations of 11 replicate extractions of 1.0 μg L-1 level were L9%～4.1%, with the detection of limits were as low as 1.8-3.7 ng L"!. In order to validate the developed method, the certified reference materials of GBW 08607 (water) and GBW 10043 (rice) samples were analyzed which found it were in good agreement with the certified values. The application of this method for the separation and preconcentration of water and biological samples gave high recoveries (90.6%-106.0%).