| As the quality of our life continually improved and the animal foods diet as the source of nutrients in an important part in the food has increased year by year. And the accelerated industrialization process has made the environment and health into the public's concern. the heavy metal level in animal-derived food aroused extensive concern in the international community. Heavy metal is the proportion of the metallic elements of which density are more than 5. Except for copper, zinc, manganese and other elements are necessary minor elements for human body, most of the metal elements such as mercury, cadmium, lead, arsenic and chromium, take no effect to our body while accumulating and producing toxicity in our body. If the heavy metal level is above the maximum limited quantity, it will be a serious threat to human health. This article to the source of food animals, has optimized the use of microwave decomposition method, and set up the fluorescent spectrometry and graphite furnace atom absorption spectrometry, which are the fast, efficient, accurate methods in today's analysis field. After countless trials and arguments, this method of work has been concluded as follows:1. For the total mercury in animal derived food, we use microwave decomposition to process the samples. Innovative solutions are carried out to diminish the interference of nitrogen oxides by optimizing the reducing agent, carrier, and the ratio of the digestion solution conditions. The instrumental detective limit is 0.12μg·L-1.The concentration of standard curve range from 0 to 2.0μg·L-1 presents a good linear relationship. Pork standard material GBW08552 is used for Method validation and quality control concentrations of mercury on the machine range from 1.7 to 1.9μg·L-1.Recovery range from 82.5% to 108.8%.The relative standard deviation is 6.5%.With this method we determined a number of pork and chicken in several cities and no one has exceeded the amount of total mercury limits according to "limited food contaminants GB2762-2005".2. For inorganic arsenic in animal-derived food we use acid to hydrolysis the samples and determine them by hydride generation-atomic fluorescence spectrometry. The rational conditions in process, such as reaction time, addition of n-octanol and the concentration of potassium iodide-thiourea, have been selected. The instrumental parameters were also adjusted. Being tested, the precision in the determination of inorganic arsenic is 3.2%, while the standard curve ranges from 0 to 50μg·L-1 with good linearity. Pig liver and chicken standard materials are used for method validation and quality control. By determination the average measured livers contain inorganic arsenic 47.10μg·L-1, RSD is 2.4%, its recovery range from 97.3 to 111.5%; The average measured chicken contain inorganic arsenic 107.90μg·L-1, RSD is 5.3%, its recovery range from 90.8% to 103.5%.With this method we determined 56 eggs traced from several provinces, including one fresh egg containing more inorganic arsenic than the limited amount according to "limited food contaminants GB2762-2005".3. For lead, chromium and cadmium in animal-derived food we use microwave digestion to process the samples and determine them by graphite furnace atomic absorption spectrometry. Determination parameters of instrument and the atomization process were tuned to achieve the best condition, and choose the most appropriate matrix modifier to enhance absorption and reduce background noise.pig liver standard material is used for method validation and quality control. By determination the recovery of lead in pig liver standard material range from 90.7% to 105.5% and RSD is 4.1%;The recovery of cadmium range from 91.0% to 97.0% and RSD is 3.2%;The recovery of chromium range from 81.0% to 89.0% and RSD is 4%.With this method we determined a number of eggs,sheep kidneys and cattle kidneys. Some of these samples contain more heavy metal than the limited amount according to "limited food contaminants GB2762-2005" respectively. |
PDF Full Text Request