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目的探讨微波消解法和湿法消解法在前处理食品(米粉和麦粉)中对食品总砷含量测定结果的影响。方法根据国家标准GB 5009.11-2014总砷中第二法(氢化物发生原子荧光光谱法),分别采用微波消解与湿法消解法对质控样品和试样样品消解处理后进行总砷含量测定。结果两种处理方法测定食品(米粉和麦粉)中总砷,其含量为0.726 mg/kg时,两法精密度、准确度都较高(RSD<2%,回收率为112%115%),试样样品检测结果差异无统计学意义(t=0.723,P>0.05);在总砷含量为0.317 mg/kg时,湿法消化检测结果准确性很高(RSD<2%,用“z-比分数”法对测试结果进行评价,z值均≤2),而用微波消解法检出总砷含量为0.222 mg/Kg,仅为质控样品含量的70%(RSD=2.8%),内质控样品两种方法检测结果差异有统计学意义(t=7.491,P<0.05)。国标规定,谷物中总砷含量限值为0.5 mg/kg,本次试验以此值为分界值,低于0.5 mg/kg的样品称为总砷含量较低的样品,而高于0.5 mg/kg的样品称为总砷含量较高的样品。结论微波消解法和湿法在消解麦粉和米粉样品时,总砷含量高,两种方法测定结果一致性好。样品总砷含量低时,湿法消解处理待测样品,检测结果可靠。
Objective To investigate the effect of microwave digestion method and wet digestion method on the determination of total arsenic in foodstuffs (rice flour and wheat flour). Methods According to the second method of total arsenic in national standard GB 5009.11-2014 (hydride generation atomic fluorescence spectrometry), the content of total arsenic in the control samples and the sample samples were determined by microwave digestion and wet digestion respectively. Results The total contents of total arsenic in food (rice flour and wheat flour) were higher than those of the control group (0.726 mg / kg) by the two methods. The precision and accuracy of the two methods were higher (RSD <2% and recovery of 112% and 115% (T = 0.723, P> 0.05). When the total arsenic content was 0.317 mg / kg, the results of wet digestion were highly accurate (RSD <2%, using “z - score ratio ”method, the value of z was ≤2), while the total arsenic content was 0.222 mg / Kg by microwave digestion, which was only 70% of the control sample (RSD = 2.8%) There was significant difference between the two methods (t = 7.491, P <0.05). According to the national standard, the total arsenic content in cereals is limited to 0.5 mg / kg. The value of this test is used as the cut-off value. Samples below 0.5 mg / kg are called samples with low total arsenic contents, while those above 0.5 mg / kg of the sample is called a high total arsenic samples. Conclusion Microwave digestion method and wet method in the digestion of wheat flour and rice flour samples, the total arsenic content is high, the consistency of the results of the two methods is good. When the total arsenic content of the sample is low, the sample to be tested is digested by wet digestion and the test result is reliable.