Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna, B. Ubertini, Via Bianchi 9, 25124, Brescia, Italy.
J Mass Spectrom. 2012 Sep;47(9):1221-31. doi: 10.1002/jms.3066.
Since 2008, the analyses carried out in the Lombardia region as part of National Residue Control Plans have evidenced unexpected frequent detection of the corticosteroid prednisolone (PRED) in cow urine samples taken to the slaughterhouse. Considering the scarce plausibility of these high frequent findings, analytical investigations were started to ascertain the real presence of this corticosteroid. The applied confirmatory method involved liquid-chromatography low-resolution tandem mass spectrometry (triple quadrupole) as instrumental technique, and it was validated in compliance with the requirements of the Commission Decision 2002/657/EC. However, recently some criticism regarding Commission Decision 2002/657/EC identification criteria has been pointed out, experimentally demonstrating false positive results (wrong identification) although these criteria have been strictly observed. Therefore, considering the serious implications (i.e. the possibility that PRED could be considered endogenous in particular animal conditions), studies were carried out to investigate the reliability of PRED identification through the change of the chromatographic conditions (mobile phases, gradient and analytical column) of the confirmatory procedure routinely applied. Further confirmation came from the application of high-resolution mass spectrometry technique (MS(2) and MS(3) experiments) to analyze incurred cow urines samples. All the obtained results confirmed definitively the real presence of this corticosteroid excluding false-positive findings in routine analysis. In addition, other experiments demonstrated that high-resolution mass spectrometers (Time of Flight and Orbitrap technologies) could be successfully applied to routine determination of steroid residues in biological fluids at very low concentrations (< 1 µg L(-1)).
自 2008 年以来，伦巴第大区作为国家残留控制计划的一部分进行的分析表明，在送往屠宰场的牛尿液样本中，经常出人意料地检测到皮质甾醇泼尼松龙（PRED）。鉴于这些高频发现的可能性不大，因此开始进行分析调查，以确定这种皮质甾醇的实际存在。应用的确认方法涉及液相色谱-低分辨率串联质谱（三重四极杆）作为仪器技术，并根据委员会第 2002/657/EC 号决定的要求进行了验证。然而，最近有人对委员会第 2002/657/EC 号决定的识别标准提出了一些批评，尽管严格遵守了这些标准，但实验证明存在假阳性结果（错误识别）。因此，考虑到严重的影响（即 PRED 可能被认为是特定动物条件下的内源性物质），进行了研究，以通过改变常规应用的确认程序的色谱条件（流动相、梯度和分析柱）来研究 PRED 识别的可靠性。进一步的确认来自于应用高分辨率质谱技术（MS(2)和 MS(3)实验）分析受污染的牛尿液样本。所有获得的结果都明确证实了这种皮质甾醇的实际存在，排除了常规分析中的假阳性发现。此外，其他实验表明，高分辨率质谱仪（飞行时间和轨道阱技术）可以成功地应用于生物体液中极低浓度（<1μg/L）的类固醇残留的常规测定。
