Determination Of Iodine, Chromium In Foods And Mercury In Antimony Ingot By Atomic Fluorescence Spectrometry

In recent years, people are paying more and more attentions to food safety. To ensure people have a healthy diet, monitoring and controlling food quality has become the primary task of market supervision and assurance. At the same time, it is imperative to keep industry to be healthy development. The development of high purified metal materials has made breakthrough progress in our country, and part of the material has been exported into the international market, but compared with developed countries, there are still some gaps and insufficiency in quality. Either food or purified metals, the detection techniques of trace elements are facing great opportunities and challenges. Nowadays, developing the detection method with high sensitivity and low detection limit has become the primary task for the analytic chemists.This paper briefly described the development and research status of atomic fluorescence spectrometry. Based on the summarization of research results in the analysis method of atomic fluorescence spectrometry and the relevant knowledge, we have investigated the new methods of detecting iodine, chromium in food and the mercury in antimony. In order to set up the analytic method with low detection limit, high sensitivity and applicable to real samples, the researches involved are summarized as follows.A method for the determination of iodine based upon a compound H2HgI4formed between I-and Hg2+in nitric acid medium and extracted by methyl isobutyl ketone (MIBK), was developed for atomic fluorescence spectrometry (AFS). The experiment dealing with the sampling system of the atomic fluorescence spectrometer was constructed. Using the methods of head-space and cold vapor atomic fluorescence spectrometry to determine the mercury indirectly was realized for iodine. Experimental parameters such as the conditions of extraction reagents, aqueous phase acidity, elemental mercury diffusion temperature in a vial and other factors were investigated and optimized. Under the optimum experimental conditions, this method showed a detection limit of0.038μg·L-1iodine and a linear relationship between0.04～20μg·L-1. The method was applied to determine the iodine content in marine products, showing a relative standard deviation (RSD) of2.2%and the recoveries in the range of98.1%～102.5%.The determination of iodine in milk powder was based on that I-reduced the added As(Ⅴ) to As(Ⅲ) in an acidic medium, the resultant As(Ⅲ) could be determined by HG-AFS in terms of iodine. Experimental parameters such as the instrumental and reaction conditions were investigated and optimized. The wet digestion of samples was carried out to guarantee no original arsenic left. The experimental results showed a detection limit of0.07μg·L-1iodine and a linear relationship between0.10～60μg·L-1. The method was verified by certified standard reference materials and applied to determine infant formula powders with relative standard deviation (RSD) of0.80%-1.05%, resulting in an analytic method with simple, accurate and sensitive merits.In an acidic medium, Cr(Ⅵ) oxidized As(Ⅲ) to As(Ⅴ), the residual As(Ⅲ) content was determined by hydride generation-fluorescence spectrometry, which was inversely proportional to Cr(Ⅲ) and Cr(Ⅵ) content. The sample digestion procedure was investigated. This experiment optimized the instrumental operation parameters, reaction acidity and other influence factors. The experimental results showed a linear relationship between0.4～20μg·L-1Cr. The detection limit of the method was2.5μg·L-1. When the method was applied to milk analysis, the relative standard deviation (RSD, n=6) of1.6%-2.7%was found. The recovery was96.5%～104.2%.Based on that the mercury could be extracted to the organic phase of methyl isobutyl ketone, a method for determination of mercury in antimony ingot and its oxide by methyl isobutyl ketone extraction-hydride generation atomic fluorescence spectrometry was established. The method of dissolving sample and the effect of concomitant ion on the target determination were studied. Experimental parameters such as the conditions of extraction, acidity, temperature and other factors were optimized. The result showed mercury content with a linear relationship in0.02～50μg·L-1.The method detection limit was0.013μg·L-1. The method was applied to determine the mercury content in antimony ingot and its compound. The relative standard deviation was0.65%～2.40%and the recoveries were in the range of94.3%-99.4%. The study provided a simple and accurate method to detect mercury in antimony.