The survey on overmeasure of inorganic arsenic in seaweed

China is a large seaweed-producing country,and the seaweed is one of peoples favorite healthy foods.However,over-standard inorganic arsenic,which is bad for health,has been detected in seaweed recently,according to the newly promulgated sanitation standards of seaweed and the standard method of detecting inorganic arsenic in food.In order to analysis the causes of over-standard inorganic arsenic in seaweed,the author used the national stated methods to analysis the content of general arsenic and inorganic arsenic in seaweed such as laver and kelp from home and abroad.Meanwhile,the variability of inorganic arsenic contained in fresh laver of different harvest periods,together with their processing products,and the water of culturing farms has been carefully measured.The results were as follows:Firstly,the inorganic arsenic exceeded the standard at large,with the ratio of overmeasure up to 100%,according to the standard of GB 16643-2005 and its detecting methods.Especially the difference of percentage of inorganic arsenic to general arsenic fluctuated greatly,from the minimum discrepancy 27.0% to the maximum 79.4%.Secondly,the minimum amount of inorganic arsenic in the water of culturing farms was 0.26 mg·kg-1,on the contrary,the maximum amount was up to 3.16 mg·kg-1.The content of inorganic arsenic was different not only during different harvest times from the same laver culturing farm but also from different culturing farms and different seasons.The amount of inorganic arsenic in laver of first crop was highest and the lower in latter crops.Overall,there was no a linear relationship between the contend of inorganic arsenic in laver and in the water of culturing farms.Thirdly,the matter of overmeasure inorganic arsenic was also presented in the test of different brands laver from home and abroad with the GB/T 5009.11-2003 stated method.With the Hydride Generation Atomic Fluorescence Spectrometry method,the range of superscale was 5.3-15.5 times to the standard limits,the ratio of overmeasure up to 100%,while the ratio was 86.4%,1.3-1.9 times to the standard limits using the Silver Diethyl-dithiocarbamate method.Hence biggish difference was observed between two test methods.In conclusion,arsenic was always formed as small molecule organic arsenic in seaweed,which would disturb the results under the Hydride Generation Atomic Fluorescence Spectrometry method and the Silver Diethyl-dithiocarbamate method to some extent.Therefore,the two detecting methods of GB/T 5009.11 shouldn't be applied to test inorganic arsenic of seaweed owing to the different results with different testing methods.Recently,enterprises and consumers are puzzled at the delimitation of inorganic arsenic in seaweed without uniform standard.Whereas the special presence of arsenic element in seaweed,not bad for health,it was needless to restrict the amount of inorganic arsenic in seaweed..