In this work, we developed a HPLC method for the multidetermination of avermectins (AVM) (abamectin—ABA 1b and ABA 1a, eprinomectin—EPR, and ivermectin—IVM) and milbemycins (moxidectin—MOX) in milk samples using polypyrrole (PPy) as adsorbent material in pipette-tip solid-phase extraction (PT–PPy–SPE). PPy was characterized by scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, and X-ray diffraction and the data agreed with the literature. The sample preparation included the clean-up of the milk by protein precipitation (PP) with acetonitrile and extraction of the analytes by PT–PPy–SPE. The chromatographic method was developed in reverse phase and isocratic mode with flow rate at 1.2 mL min⁻¹ and ultraviolet detection at 250 nm. The mobile phase composition was acetonitrile:methanol:water (55:25:20, v/v/v). The studied parameters and the optimized conditions for the sample preparation were washing solvent (300 μL water), volume and type of eluent (500 μL methanol), volume and pH of sample (1 mL and pH 10), amount of adsorbent material (50 mg PPy), and without addition of salt (NaCl). The method was linear over the concentration range from 20 to 3000 ng mL⁻¹ with coefficients of correlation (r) ≥ 0.99 for all analytes and recoveries around 100%. The method developed and validated was used for the analyses of real milk samples from cow treated with Ivomec^® (IVM 3.5%), in which were found 21.51 ± 2.94 ng mL⁻¹ of IVM. Finally, the results proved that PT–PPy–SPE coupled to HPLC–UV was economical, simple, and easy-to-perform technique.

Open image in new window

在这项工作中，我们开发了一种使用多吡咯（PPy）测定牛奶样品中阿维菌素（AVM）（阿维菌素-ABA 1b和ABA 1a，依普诺菌素-EPR和伊维菌素-IVM）和米尔倍霉素（moxidectin-MOX）的多测定法。作为移液器尖端固相萃取（PT–PPy–SPE）中的吸附材料。通过扫描电子显微镜，热重分析，傅立叶变换红外光谱和X射线衍射对PPy进行表征，数据与文献一致。样品制备包括通过蛋白质沉淀（PP）和乙腈净化牛奶，以及通过PT–PPy–SPE提取分析物。色谱法以反相和等度模式开发，流速为1.2 mL min ^-1和在250 nm处进行紫外线检测。流动相组成为乙腈：甲醇：水（55:25:20，v / v / v）。样品制备的研究参数和优化条件是洗涤溶剂（300μL水），洗脱液的体积和类型（500μL甲醇），样品的体积和pH（1 mL和pH 10），吸附材料的量（50 mg PPy），并且不添加盐（NaCl）。该方法在20至3000 ng mL ^-1的浓度范围内是线性的，所有分析物的相关系数（r）≥0.99，回收率约为100％。用于真实牛奶样品从与处理的Ivomec牛的分析开发和验证的方法，^®（IVM 3.5％），其中发现了21.51±2.94 ng mL ^-1的IVM。最后，结果证明PT-PPy-SPE与HPLC-UV联用是经济，简单且易于执行的技术。

在新窗口中打开图像