Garber Eric A E
Division of Bioanalytical Chemistry, Office of Regulatory Science, Center for Food Safety and Applied Nutrition, US Food and Drug Administration, College Park, Maryland 20740, USA.
J Food Prot. 2008 Mar;71(3):590-4. doi: 10.4315/0362-028x-71.3.590.
Recent cases of adulteration with melamine have led to the need for rapid and reliable screening methods. To meet this need, commercial enzyme-linked immunosorbent assay (ELISA) test kits for the detection of triazines were evaluated. The recently released Melamine Plate kit (Abraxis, Warminster, Pa.) displayed a limit of detection of 9 ng/ml for melamine in phosphate-buffered saline (PBS) and approximately 1 microg/ml for melamine added to dog food. An atrazine ELISA test kit produced by Abraxis required 0.2 mg/ml to generate a response more than four times the standard deviation from background. In contrast, with the EnviroGard Triazine Plate kit (Strategic Diagnostics, Inc., Newark, Del.), 1.5 mg/ml melamine in PBS generated a signal only one standard deviation from background, which was insufficient to define a limit of detection. Extraction based on dilution with 105 mM sodium phosphate/75 mM NaCl/2.5% nonfat milk/0.05% Tween 20 (UD) enabled detection of fivefold less melamine in dog food than did use of the procedure recommended by the manufacturer, which entailed extraction into 60% methanol, sonication, centrifugation, filtration, and further dilution into 10% methanol/PBS. Using the Abraxis Melamine ELISA, both extraction protocols yielded identical results with a dog food sample adulterated with melamine. The recovery of melamine spiked into gravy from dog food using UD was 74% +/- 4%. In conclusion, the recently released Abraxis ELISA for melamine proved to be a useful alternative to more cumbersome methods.
近期三聚氰胺掺假事件促使人们需要快速可靠的筛查方法。为满足这一需求，对用于检测三嗪类的商用酶联免疫吸附测定（ELISA）试剂盒进行了评估。最近推出的三聚氰胺酶标板试剂盒（Abraxis公司，宾夕法尼亚州沃敏斯特）在磷酸盐缓冲盐水（PBS）中对三聚氰胺的检测限为9纳克/毫升，添加到狗粮中的三聚氰胺检测限约为1微克/毫升。Abraxis公司生产的一种莠去津ELISA试剂盒需要0.2毫克/毫升才能产生比背景标准差高四倍以上的响应。相比之下，使用EnviroGard三嗪酶标板试剂盒（Strategic Diagnostics公司，特拉华州纽瓦克）时，PBS中1.5毫克/毫升的三聚氰胺产生的信号仅比背景高一个标准差，不足以确定检测限。基于用105毫摩尔磷酸钠/75毫摩尔氯化钠/2.5%脱脂牛奶/0.05%吐温20（UD）稀释的提取方法，与使用制造商推荐的方法（即提取到60%甲醇中、超声处理、离心、过滤并进一步稀释到10%甲醇/PBS中）相比，能够检测到狗粮中含量低五倍的三聚氰胺。使用Abraxis三聚氰胺ELISA试剂盒，两种提取方案对掺有三聚氰胺的狗粮样品产生的结果相同。使用UD从狗粮中添加到肉汁中的三聚氰胺回收率为74%±4%。总之，最近推出的Abraxis三聚氰胺ELISA试剂盒被证明是一种比更繁琐方法更有用的替代方法。
