Iodine Contents In Chinese Grains And Vegetables And The Influence Of Iodine Emitted From Coal Combustion On Them

In this study, pyrohydrolysis was used for the iodine with the volatile chemistry character released and collected from the samples for determination. Because there is no need to add other reagents, the samples have the advantages of non-contamination, low blank values, and the iodine released completely from the samples. The catalytic spectrophotometric (CS) method with the outstanding advantages of high sensitivity, low cost of analysis and simple equipment, has been used widely as the classic method for the accurate trace iodine determination. So the pyrohydrolysis-CS method is the first choice for the micro-iodine determination. In order to improve the sensitivity, precision and accuracy of the CS method, the optimal design through orthogonal experiment was used in the pyrohydrolysis for the pre-treatment and the reaction time and temperature were optimized in the CS method. The optimization lowered the limit of detection and reliable quantization, which were 0.3 ng/g,0.9 ng/g, respectively. So the micro-iodine analysis for the plants (especially foodstuffs) was constructed with the simple method and the accuracy and precision meeting the requirements of analysis.The iodine contents of the grains and the vegetables in different regions of China were analyzed systematically. It was concluded that the average iodine content in main grains (rice, wheat, corn) was about 0.011μg/g. The results show that vegetables and the grains as sources of iodine contribute little to the residents in China, which give a new location for the iodine intake in Chinese diet. The iodine contents of different plants in different districts varied differently. The reasons were mainly related to the volatility of iodine in soil, various kinds of corps and the different absorption of corps on various forms.By analyzing the iodine contents in Chinese grains and vegetables, it was found that the various iodine concentrations in crops were:chili> soybean> grains. Although they are all fruiting parts or seeds, the accumulated dose of iodine was less than that in other parts in the same plant. The ability of the fruits of vegetables accumulated the iodine was easier than the seeds in grains. In this study, the iodine content in rice and chaff were determined, and it was found that the iodine content in chaff was higher than that in rice, which had practical significance for the processing and application of foods, fodder.The medium of iodine carriers (chili, corn) for the iodine intake of local residents in the pollution of fluorosis in Guizhou was studied. The results showed that the iodine accumulated factors of baked corn and chili were 3.2,30 respectively. As the chili absorbed more iodine in the air, and the accumulation factors of chili was 9 times than that of corn. The iodine intake from the non-baked chili and corn was 17.6μg, and from the baked ones was 66.4μg. So the local residents consume additional 48.8μg iodine daily due to the baking of soot.