An immunoassay for ochratoxin A without the mycotoxin

Phage display peptide libraries allow the selection of new molecules capable of mimicking the structural and functional features of native proteins or chemicals. This technology can be applied to developing new reagents, which may serve as the surrogate of the original objects. In order to screen peptides capable of mimicking ochratoxin A (OTA) in the interaction with anti-OTA monoclonal antibody (McAb) and establish the immunoassay for OTA, an anti-OTA McAb was used as the target for panning-elution selection from a phage random seven-peptide library. After four rounds of panning, 11 phages were found to be able to mimic OTA in binding with the antibody. Enzyme-linked Immunosorbent Assay (ELISA) for detecting OTA was established with the phages. In the most sensitive assay, the linear range of the inhibition curve was 200–8000 pg/ml; the detection limit was 150 pg/ml. The inserted peptide sequences were deduced by DNA sequencing. The common amino acid residue sequence was IR(V)PMV(L)XX (X is any amino acid residues), which was verified by two synthesized peptides. The results demonstrated that those phage peptides could be used as the surrogate of OTA to establish the immunoassay.     

固相萃取-高效液相色谱-串联质谱法同时测定鸡蛋中42种农药残留

目的 建立固相萃取-高效液相色谱-串联质谱法同时测定鸡蛋中42种农药残留的检测方法。方法 样品经加水分散后,用乙腈提取,PRiME HLB固相萃取柱进行净化处理,采用Shim-pack XR-ODSⅡ色谱柱(75 mm×2.0 mm, 2.2 μm)分离,5 mmol乙酸铵水溶液(A)-甲醇溶液(B)为流动相,进行梯度洗脱;质谱法选择电喷雾离子源ESI,正负离子分段扫描,多反应监测(MRM)模式检测,基质匹配标准溶液外标法定量。结果 42种农药的峰面积与质量浓度在0.1~2 ng/mL范围内呈现良好的线性关系,相关系数r均大于0.994;方法检出限(LOD, S/N=3)为0.04~0.3 μg/kg,定量限(LOQ, S/N=10)为0.1~1.0 μg/kg。在1.0、2.0、5.0、10 μg/kg四个添加水平下,42种农药平均加标回收率为61.0%~118.5%,相对标准偏差为0.8%~9.9%。结论 该方法具有操作简单、分析时间短、试剂用量少、灵敏度高且重复性好等特点,适用于鸡蛋中农药残留的高通量快速检测分析。     

利用LAMP技术快速检测羊肉制品中的鼠源性成分

为实现羊肉制品中鼠源性成分的定性检测,基于环介导等温扩增（loop-mediated isothermal amplification,LAMP）技术,以鼠的线粒体基因（大鼠环氧化酶基因KP244683.1和小鼠的16S rRNA基因KY018919.1）为靶标,分别设计相应的LAMP特异性引物,通过优化反应条件,确定最佳LAMP反应体系。对混合模拟样品进行特异性、灵敏度和稳定性评估,应用LAMP和聚合酶链式反应检测方法分别对市售羊肉制品进行检测,对比分析检测结果。结果表明,本研究建立的LAMP方法特异性强,大鼠和小鼠的检出限分别为0.1%和0.5%,稳定性好,LAMP与聚合酶链式反应市售实际样本检测结果具有高度的一致性。因此,本实验建立的鼠源性成分LAMP检测方法操作简便、高效、准确,为鼠肉掺假快速诊断和基层诊断提供了新的选择,可作为羊肉制品中鼠源性成分的快速检测新方法。