The Study Of Occurrence And Estimated Dietary Intakes Of Perchlorate And Bromate In China

Perchlorate and bromate were two kinds of important persistent inorganic pollutants, which are increasingly concerned due to the thyroid disrupting effect of perchlorate and the potentially carcinogenicity of bromate. This study is focused on these two chemicals in foodstuffs. On the basis of the establishment of a reliable analytical methodology, perchlorate and bromate in daily foodstuffs and dietary samples were determined and a simple dietary exposure assessment was performed.A comprehensive ananlytical method was developed using ion chromatography tandem mass spectrometry (IC-MS/MS) with stability isotope dilution technology for the simultaneous determination of perchlorate and bromate in varity of foodstuffs, including vegetable, animal producing foods, cereals and dietry samples. The food samples surrogated with18O marked internal standard were extracted by water and acetonitrile. The extracts were then purified by an EnviTM Carb SPE cartridge. With the hydrophilic Ion Pac AS19column and linear gradient potassium hydroxide used as eluent, bromate and perchlorate were analyzed by a triple quadrupole mass spectrometer under negative electronspray ionization mode and multiple reaction monitoring (MRM). Good linearities were achieved for bromate and perchlorate over the range of0.1-50μg/L and0.05-50μg/L, respectively, with correlation coefficients R2>0.998. The quantification limits of the method were0.1μg/L-2μg/kg and0.5μg g/L-1.0μg/kg for bromate and perchlorate, respectively. Mean recoveries of two target analytes (spiked at three concentration levels) ranged from80.3%to123.8%, with within-day precisions no more than21.4%and intraday precisions no more than12.2%, which complied with the regulations for determination of trace contaminants residues in food matrix. This method could be applied in the simultaneous detection of bromate and perchlorate in different foodstuffs.The144dietary mixture samples collected from12provinces in Chinese Total Diet Study in2007were analyzed using the established method.Perchlorate was detected91.7percent of dietary samples, with a concentration range of0.14μg/L-70.91μg/kg, while bromate was found only in two samples. Relatively high level of perchlorate occurred in vegetables, fruits and grains, corresponding to the concentration range of3.11-46.44μg/kg,4.03-12.28μg/kg and3.14-70.91μg/kg, respectively. The two highest concentrations were observed in the cereals from Fujian and Jiangxi provinces. The estimated dietary intake of perchlorate for a standard male in China averaged0.65μg/kg bw/day, which closed to the reference dose recommended by National Accademy of Science, US, however, was higher than the value resulted from American Diet Study in2005-2006and the relative study conducted in Canada.