Determination Of Mercury In Vegetables By Nano Silver

Mercury element is volatile, highly toxic and widely used, extremely hazardous for both environment and human health. The technology of detecting the content of mercury in food has been one of the major concerns in our country. However, traditional detecting methods for Hg2+ require expensive equipment and complex pre-treatment. Also, they are easily affected and hard to meet the requirements of practical inspection. This paper establishs a rapid and accreate method for Hg2+ in aqueous solution using nano-silver with the ultraviolet-visible absorption spectra. In addition, this method could be utilised in actual vegetable samples.This paper adopted chemical reduction method in aqueous solution to prepare spherical nano-silver particles(Ag NPs). Finally it formed uniformly distributed and well dispersed spherical nano-silver which average diameter is 3.9 nm、9.2 nm、15.9 nm and 22.0 nm. UV-visible spectroscopy was used to detect the dependence between the absorbance of AgNPs and the concentration of Hg2+. A well linear relation had been found between them. Based on this relation, this paper established a method to test Hg2+in aqueous solution. Transmission electron microscope (TEM) revealed the difference of the surface morphology of Ag NPs before and after the detection of Hg2+. It was found that AgNPs and Hg+ solution could generate redox reaction at room temperature, which led to the gradually decrease of the absorbance of AgNPs with well linear relation with the increasing concentration of the concentration of Hg2+The influence that the size of AgNPs to the detecting of its performance were explored that the highest sensitivity of Ag NPs is filtered which the size is 3.9nm. With a month, the Ag NPs maintained excellent stability under the condition of protected from light at the room temperature. High selectivity of Ag NPs for Hg2+ had been found in the presence of other ions such as Mg2+、Ca+, ect. A method was estabilised for the detection of Hg2+ in aqueous solution with the limit of 0.7 g/L, and the linear regression equation is A= 0.774-0.023cHg2+ (g/L), R=0.999. Rrecovery experiment was used in the test of mercury of drinking water, and the recovery rates were 97.5% to 102.5%. What’s more, in the seven independent tests, the content of mercury in drinking water was RSD= 0.39%, which indicated that the method had good accuracy and precision.By the established testing method, this paper tested for Hg2+ in four samples belong to root vegetables, leafy vegetables, melons, and aquatic vegetable. The samples were pre-digested with nitric acid and perhcloric acid. The results showed that the recovery was found to be in the range of 87.6% to 106.9%, and seven independent test of the RSD was 7.5% to 8.3%. The experimental results indicated that the AgNPs had well accuracy in the test of mercury in vegetables.