Dept. of Chemistry, Istituto Zooprofilattico Sperimentale del Mezzogiorno, via Salute 2, Portici, NA 80055, Italy.
Rapid Commun Mass Spectrom. 2012 Apr 15;26(7):733-9. doi: 10.1002/rcm.6154.
Test methods have to be developed by laboratories for official control to monitor possible misuse of veterinary drugs in animal productions, also through feeding stuff. A novel method for identification and quantification of levamisole in feeds by liquid chromatography coupled to electrospray mass spectrometry in an ion trap (LC/ESI-MS/MS) is herein described; after a single-step cleanup by liquid-liquid extraction from the feed and separation by reversed-phase liquid chromatography, levamisole was determined and unambiguously confirmed by tandem mass spectrometry, on the basis of two product ions. The method was in-house validated, according to the Regulation 882/2004/EC, evaluating trueness, repeatability, within-laboratory reproducibility, ruggedness, specificity, and the limit of quantification (LOQ). The method is reliable and specific for complete and complementary feeds for pigs, cattle, rabbits and poultry; very good mean recoveries (higher than 92 %) and precision (RSD values < 15.2%) were attained. The LOQ at 2.0 mg/kg was verified. Moreover, we describe how the method was developed to support Italian Police investigations regarding illegal treatments of pigs; in this case, since the drug(s) added to the feed were unknown, a preliminary untargeted analysis was performed by full scan mass spectrometry on an ion trap, from 50 up to 2000 m/z; the presence of levamisole was hypothesised, on the basis of the most abundant ion and its fragmentation pattern. Then, levamisole was unambiguously confirmed by the ion trap LC/ESI-MS/MS method.
测试方法必须由实验室开发，以便官方控制监测动物生产中（包括饲料）兽用药物的可能滥用。本文描述了一种通过电喷雾质谱在离子阱中（LC/ESI-MS/MS）鉴定和定量饲料中左旋咪唑的新方法；通过饲料的液-液萃取和反相液相色谱进行单一的净化步骤后，基于两个产物离子，通过串联质谱法对左旋咪唑进行了确定和明确的确认。该方法是根据 2004 年 8 月 28 日的 882/2004/EC 法规进行内部验证的，评估了准确度、重复性、实验室内再现性、稳健性、特异性和定量限（LOQ）。该方法适用于猪、牛、兔和家禽的全价和补充饲料，具有很高的可靠性和特异性；平均回收率（高于 92%）和精密度（RSD 值低于 15.2%）都非常好。验证了 2.0 mg/kg 的 LOQ。此外，我们还描述了如何开发该方法来支持意大利警方对猪的非法处理的调查；在这种情况下，由于添加到饲料中的药物未知，因此通过离子阱的全扫描质谱对其进行了初步的非靶向分析，范围为 50 至 2000 m/z；基于最丰富的离子及其碎片模式，假设存在左旋咪唑。然后，通过离子阱 LC/ESI-MS/MS 方法明确地确认了左旋咪唑。
