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    测定海产品中5种砷形态国家标准方法的改进

    Improvement of National Standard Method for Determination of 5 Arsenic Species in Marine Products

    • 摘要: 国家标准GB 5009.11-2014测定食品中砷形态含量时,前处理方法需经放置过夜、热提取、离心、萃取及过滤等较多步骤,耗时较长,且测定方法高效液相色谱-电感耦合等离子体质谱法(HPLC-ICP-MS)中流动相需配制4种不同含量的无机盐,还须调节流动相酸度,较为复杂。针对上述问题,改进了国家标准前处理方法,优化了国家标准第二法的色谱条件,提出了基于微波辅助酶提取-HPLC-ICP-MS快速测定食品中5种砷形态含量的方法。将样品1.0 g、链霉蛋白酶E酶0.004 g和水20 mL置于微波提取仪中,于35℃提取45 min,提取液离心10 min,再经0.45 μm水性滤膜过滤即得样品溶液。以Hamilton PRP-X100色谱柱为固定相,体积比99:1的2.0 mmol·L-1的磷酸二氢铵溶液(pH 8.0)-乙醇的混合液为流动相等度洗脱,按仪器工作条件进行测定。结果表明:5种砷形态的标准曲线的线性范围均为2.5~30.0 μg·L-1,检出限(3s/k)为0.50~0.60 μg·L-1。按标准加入法进行回收试验,回收率为90.0%~103%,测定值的相对标准偏差(n=5)为0.80%~5.0%。方法用于实际样品的分析,并与GB 5009.11-2014中第二法的测定结果进行比对,结果表明改进后的方法与GB 5009.11-2014不存在显著性差异(P>0.05)。

       

      Abstract: There were many steps in the pretreatment of national standard GB 5009.11-2014 for determination of arsenic species in food, including overnight storage, thermal extraction, centrifugation, extraction and filtration, which took a long time. The mobile phase of high performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS) should be prepared with 4 kinds of inorganic salts with different contents and the acidity of mobile phase should be adjusted, which was more complex. In order to solve these problems, the pretreatment of national standard was improved and the chromatographic conditions of the second method of national standard were optimized. A method for rapid determination of 5 arsenic species in food by HPLC-ICP-MS with microwave-assisted enzyme extraction was proposed. 1.0 g of the sample, 0.004 g of streptoproteinase E enzyme and 20 mL of water were placed into a microwave extractor for extraction at 35℃ for 45 min, and the extract was centrifuged for 10 min, and then filtered by 0.45 μm water-borne filter membrane. Hamilton PRP-X100 column was used as stationary phase, a mixture of 2.0 mmol·L-1 NH4H2PO4 solution (pH 8.0) and ethanol at a volume ratio of 99:1 was used as the mobile phase for isocratic elution, and the determination was carried out according to the working conditions of the instrument. As shown by the results, the linear ranges of the standard curves of 5 arsenic species were all 2.5-30.0 μg·L-1, with detection limits (3s/k) in the range of 0.50-0.60 μg·L-1. Test for recovery was made by standard addition method, giving results in the range of 90.0%-103%, with RSDs (n=5) of the determined values in the range of 0.80%-5.0%. The method was applied for analysis of samples and in comparison with the results given by the second method of GB 5009.11-2014, showing that there was no significant difference between the improved method and GB 5009.11-2014 (P>0.05).

       

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