微波消解法与湿法消解法在测定食品总砷中的比较

Comparison of microwave and wet digestion method for determination of total arsenic in food

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 explore effects of microwave digestion and wet digestion method in the pretreatment of food （ rice noodles and flour） on determination of total arsenic in food. Methods According to the national standard second GB 5009.11 -2014 method （hgafs ）, microwave digestion and wet digestion method for the determination of total arsenic in quality control samples and sample digestion was used. Results Determination of total arsenic was tested in food by two methods. When its content was 0.726mg/kg, the precision and accuracy [ recovery rate was 112 - 115%, RSD 〈 2% ） was both higher. There was no significant difference in the test results of the samples （ t = 0. 723 ,P 〉 0.05 ）. When its content was 0.317mg/kg, the accuracy of wet digestion test was very high （ RSD 〈2%, z≤2）. The total arsenic content was 0. 222mg/kg detected by microwave digestion method, which was 70% of the quality control sample （RSD = 2.8% ）. The difference between the two methods was statistically significant （ t = 7. 491, P 〈 0.05 ）. According to the national standard, the total arsenic content in cereal limit was 0.5 mg/kg. This experiment with this value was as a boundary value. The sample with value less than 0.5 mg/kg was called sample with low total arsenic content, and sample with value higher than 0. 5 mg/kg was called sample with high total arsenic content. Conclusion When the total arsenic content was high, the methods of microwave digestion and wet one in the pretreatment of food （ rice noodles and flour） were in good agreement. When the total arsenic content was low, the wet digestion method was reliable.