Department of Bioanalysis and Drug Analysis, Faculty of Pharmacy, Medical University of Warsaw, 1 Banacha Street, 02-097, Warsaw, Poland.
Pharmacokinetics Department, Pharmaceutical Research Institute, 8 Rydygiera Street, 01-793, Warsaw, Poland.
J Chromatogr A. 2019 Apr 26;1591:44-54. doi: 10.1016/j.chroma.2019.01.031. Epub 2019 Jan 15.
Matrix effects are one of the most challenging issues in the analysis of complex samples using liquid chromatography coupled to mass spectrometry (LC-MS). Apart from the instrumental origin, these effects are also related to sample preparation. Cloud-point extraction (CPE) is rarely combined with LC-MS as it requires the use of surfactants which might interfere with droplet evaporation. Thus, they are suspected to cause a significant matrix effect (signal suppression). In this paper, 73 model drugs with different physicochemical properties were screened to analyse how susceptible LC-MS is to the absolute and relative matrix effect (ME) when coupled with CPE for measurements in human plasma. Three combinations of the surfactant Triton X-114 concentration (1.5% or 6%) and extraction temperature (40 or 55 °C) in six pH values gave over 1300 analyte-sample preparation condition pairs. A new term - surfactant effect (calculated for the standard solution) - allowed us to distinguish between the surfactant effect and that related to interferences from human plasma. The screening revealed that CPE combined with LC-MS is not related to a significant ME in the optimal pH of extraction. A significant absolute ME (<85% or>115%) was observed only for 25% of the analytes. Data processing (principal component analysis, classification trees, partial least squares-discriminant analysis) based on the extraction conditions and molecular descriptors helped to identify compounds prone to the matrix effect and speed up method development. A low surfactant concentration and low temperature decreased both the absolute and relative ME. pH of the extraction influenced only the relative ME. Low retention time reduced the risk of relative ME, whereas high polarity and the possibility of hydrogen bond formation minimized the occurrence of the surfactant effect and absolute ME. A significant relative ME (>15%) was observed only for 11% of the compounds, thus CPE merged with LC-MS allowed to measure drug concentrations in a reliable manner for majority of compounds. The presented approach may be further applied to other analytes and matrices.
基质效应是使用液相色谱-质谱联用（LC-MS）分析复杂样品时最具挑战性的问题之一。除了仪器本身的原因外，这些效应还与样品制备有关。浊点萃取（CPE）很少与 LC-MS 结合使用，因为它需要使用表面活性剂，而这些表面活性剂可能会干扰液滴蒸发。因此，它们被怀疑会导致显著的基质效应（信号抑制）。在本文中，我们筛选了 73 种具有不同理化性质的模型药物，以分析在与 CPE 结合用于人血浆测量时，LC-MS 对绝对和相对基质效应（ME）的敏感性。在六种 pH 值下，使用两种 Triton X-114 浓度（1.5%或 6%）和两种萃取温度（40 或 55°C）组合，共得到超过 1300 种分析物-样品制备条件对。引入一个新的术语——表面活性剂效应（针对标准溶液计算）——使我们能够区分表面活性剂效应和来自人血浆的干扰相关的效应。筛选结果表明，在最佳萃取 pH 值下，CPE 与 LC-MS 结合不会导致显著的 ME。只有 25%的分析物出现显著的绝对 ME（<85%或>115%）。基于提取条件和分子描述符的数据处理（主成分分析、分类树、偏最小二乘判别分析）有助于识别易受基质效应影响的化合物，并加速方法开发。低表面活性剂浓度和低温降低了绝对和相对 ME。萃取 pH 值仅影响相对 ME。低保留时间降低了相对 ME 的风险，而高极性和形成氢键的可能性则最小化了表面活性剂效应和绝对 ME 的发生。只有 11%的化合物出现显著的相对 ME（>15%），因此 CPE 与 LC-MS 结合可以可靠地测量大多数化合物的药物浓度。所提出的方法可以进一步应用于其他分析物和基质。
