Drug Research Program and Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, FI-00014 Helsinki, Finland.
Drug Research Program and Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, FI-00014 Helsinki, Finland; Institute of Inorganic and Analytical Chemistry, University of Münster, D-48149 Münster, Germany.
J Chromatogr A. 2019 Aug 2;1598:175-182. doi: 10.1016/j.chroma.2019.03.061. Epub 2019 Mar 28.
A new heated capillary photoionization (CPI) ion source design was developed to photoionize analytes inside a transfer capillary between a gas chromatograph (GC) and a mass spectrometer (MS). The CPI setup included a wide, oval-shaped vacuum-ultraviolet (VUV) transparent magnesium fluoride (MgF) window to maximize photoionization efficiency and thus sensitivity. The source contained a nitrogen housing around the ionization chamber inlet to avoid undesirable hydrolysis and oxidation reactions with ambient air and to maximize the proportion of formed molecular radical cations of analytes. The feasibility of the ion source was studied by analyzing 18 endogenous steroids in urine as their trimethylsilyl (TMS) derivatives with gas chromatography-tandem mass spectrometry (GC-MS/MS). The method was validated and applied to human urine samples. To our best knowledge, this is the first time that a capillary photoionization ion source has been applied for quantitative analysis of biological samples. The GC-CPI-MS/MS method showed good chromatographic resolution (peak half-widths between 3.1 to 5.3 s), acceptable linearity (coefficient of determination between 0.981 to 0.996), and repeatability (relative standard deviation (RSD%) between 5 to 18%). Limits of detection (LOD) were between 2 to 100 pg mL and limits of quantitation (LOQ) were between 0.05 to 2 ng mL. In total, 15 steroids were quantified either as a free steroid or glucuronide conjugate from the urine of volunteers. The new CPI source design showed excellent sensitivity for analysis of steroids in complex biological samples.
一种新的加热毛细管光电离（CPI）离子源设计被开发出来，用于在气相色谱仪（GC）和质谱仪（MS）之间的转移毛细管内对分析物进行光电离。CPI 装置包括一个宽的椭圆形真空紫外（VUV）透明氟化镁（MgF）窗口，以最大限度地提高光电离效率，从而提高灵敏度。该源包含一个围绕电离室入口的氮气外壳，以避免与环境空气发生不必要的水解和氧化反应，并最大限度地提高分析物形成的分子自由基阳离子的比例。通过用气相色谱-串联质谱（GC-MS/MS）分析尿液中的 18 种内源性甾体作为其三甲基硅烷基（TMS）衍生物，研究了离子源的可行性。该方法经过验证并应用于人尿样。据我们所知，这是首次将毛细管光电离离子源应用于生物样品的定量分析。GC-CPI-MS/MS 方法显示出良好的色谱分辨率（峰半宽为 3.1 至 5.3 s）、可接受的线性（决定系数在 0.981 至 0.996 之间）和重复性（相对标准偏差（RSD%）在 5 至 18%之间）。检测限（LOD）在 2 至 100 pg mL 之间，定量限（LOQ）在 0.05 至 2 ng mL 之间。总共从志愿者的尿液中定量了 15 种甾体，要么是游离甾体，要么是葡萄糖醛酸缀合物。新的 CPI 源设计在分析复杂生物样品中的甾体时表现出优异的灵敏度。
