Analytical Chemistry and Pharmaceutical Technology, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium.
Anal Chem. 2010 Jul 15;82(14):6056-65. doi: 10.1021/ac1006415.
The identification of drugs of abuse is an important issue in forensic science. The main goal is to trace and identify as many drugs as possible in the shortest possible time preferably with a simple analysis method. One possibility is to screen samples using a Liquid Chromatography-Diode Array Detection (LC-DAD) system. However, when simultaneously performing another analysis on a chromatographic column exhibiting selectivity differences from the first one, that is, orthogonal or dissimilar columns, a greater number of drugs can be possibly identified without investing a lot of extra time or money. The primary difficulty is then selecting the most appropriate columns. In this paper, it is demonstrated that selecting the most dissimilar columns based on measures such as correlation or Snyder's F(s) value is not optimal, because these measures do not take into account the identification power of the individual systems. This implies that a large number of drugs may not necessarily be identified on the systems selected using these criteria. Therefore, three other measures are tested to evaluate the identification power obtained by parallel screening on two columns or by comprehensive two-dimensional LC (LC x LC). The simplest approach is counting the number of compounds separable with a difference in retention time greater than a predefined critical value. However, this measure does not reflect the coelution pattern of the unidentified drugs nor the separation degree of all compounds. The second tested measure, information, enables differentiation between systems identifying the same number of compounds but resulting in a different coelution pattern. Multivariate selectivity, the third tested parameter, takes into account the degree of separation of all compounds and has the advantage that it reflects the gain in identification power achieved by introducing DAD data. All three proposed measures also enable evaluation of whether the corresponding LC x LC method will result in a greater identification power.
滥用药物的鉴定是法医学中的一个重要问题。主要目标是在尽可能短的时间内追踪和鉴定尽可能多的药物，最好使用简单的分析方法。一种可能性是使用液相色谱-二极管阵列检测（LC-DAD）系统对样品进行筛选。然而，当在与第一个色谱柱表现出选择性差异的另一个色谱柱上同时进行另一种分析时，即正交或不同的色谱柱，可以在不投入大量额外时间或金钱的情况下，有可能识别出更多的药物。主要的困难在于选择最合适的柱子。在本文中，证明基于相关性或 Snyder's F(s) 值等措施选择最不相似的柱子并不是最优的，因为这些措施没有考虑到各个系统的识别能力。这意味着，使用这些标准选择的系统不一定能识别出大量的药物。因此，测试了另外三种措施来评估在两个柱子上平行筛选或全面二维 LC（LC x LC）获得的识别能力。最简单的方法是计算用保留时间差值大于预定义临界值可分离的化合物数量。然而，该措施不能反映未鉴定药物的共洗脱模式，也不能反映所有化合物的分离程度。第二个测试的指标是信息，它可以区分识别相同数量化合物但导致不同共洗脱模式的系统。第三个测试的参数是多元选择性，它考虑了所有化合物的分离程度，并且具有反映通过引入 DAD 数据获得的识别能力增益的优点。所有这三个提出的措施也可以评估相应的 LC x LC 方法是否会带来更大的识别能力。
