Central Agricultural Office Food and Feed Safety Directorate, Food Toxicological National Reference Laboratory, Budapest, Hungary.
J Chromatogr B Analyt Technol Biomed Life Sci. 2012 Oct 1;906:75-84. doi: 10.1016/j.jchromb.2012.08.033. Epub 2012 Sep 1.
This paper describes a newly developed method for the simultaneous determination of eight corticosteroid residues in bovine muscle, liver and kidney samples using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The determination of methylprednisone, the main metabolite of methylprednisolone, in bovine tissues using LC-MS/MS is carried out for the first time. The method development demonstrates that the pH is important in optimizing the sample preparation. Tests performed using different solid-phase extraction (SPE) cartridges were enabled to produce conditions for reducing the matrix effects (ion suppression and enhancement) of analysis. Acidic condition and mixed-mode cation exchange SPE columns resulted in the most suitable clean-up for muscle and liver, and also yielded acceptable results for kidney. The enhanced sample clean-up resulted in excellent clear baselines of ion transitions, and therefore, a higher delta electron multiplier voltage (ΔEMV) could be set in the MS/MS detector. The application of 500 V of ΔEMV improved the signal responses, however, the noise level did not change, and consequently, the overall sensitivity and analytical limits (limit of detection, limit of quantification) could be enhanced. In the HPLC separation, the recently introduced Kinetex phenyl-hexyl core-shell type column was used that enabled baseline separation for dexamethasone and its β-epimer, betamethasone. Dexamethasone and betamethasone were eluted within 12 min and such reduced retention, obtained with core-shell HPLC type column, further enhanced the sensitivity. The method was validated according to the European Union (EU) 2002/657/EC Decision; the studied parameters met the EU standards. The decision limits and limit of detections were calculated in each matrix for all corticosteroids and varied from 0.01 to 13.3μg/kg and from 0.01 to 0. 1 μg/kg, respectively.
本文描述了一种新开发的方法，用于同时测定牛肌肉、肝脏和肾脏样品中八种皮质甾类激素残留，采用液相色谱-串联质谱法（LC-MS/MS）。首次使用 LC-MS/MS 测定牛组织中的甲基泼尼松龙的主要代谢物甲泼尼龙。方法开发表明 pH 对优化样品制备很重要。使用不同固相萃取（SPE）小柱进行的测试使分析的基质效应（离子抑制和增强）的条件得以产生。酸性条件和混合模式阳离子交换 SPE 柱导致肌肉和肝脏的最适合的净化，也为肾脏提供了可接受的结果。增强的样品净化导致离子转换的清晰基线极佳，因此，在 MS/MS 检测器中可以设置更高的 delta 电子倍增电压（ΔEMV）。500 V 的 ΔEMV 的应用提高了信号响应，但是噪声水平没有改变，因此，整体灵敏度和分析限度（检测限、定量限）得以提高。在 HPLC 分离中，使用了最近引入的 Kinetex 苯基-己基核壳型柱，它能够使地塞米松及其 β-差向异构体倍他米松基线分离。地塞米松和倍他米松在 12 分钟内洗脱，这种采用核壳型 HPLC 类型柱获得的保留时间缩短，进一步提高了灵敏度。该方法根据欧盟（EU）2002/657/EC 号决议进行了验证；研究的参数符合欧盟标准。在所有基质中，所有皮质甾类激素的决定限和检测限均从 0.01 至 13.3μg/kg 和 0.01 至 0.1μg/kg 不等。
