The number of priority and emerging contaminants nowadays exceeds several thousands. As a consequence, it is a daunting task to monitor thousands of compounds using classical gas chromatography–mass spectrometry (GC–MS). Preliminary non-targeted screening is thus usually performed to identify the most relevant contaminants. Here we analyzed complex environmental samples of snow, rain water and cloud water from the Arctic, France, Chile, and Russia by two-dimensional gas chromatography (GC × GC) with ionization methods including electron ionization (EI), positive chemical ionization (PCI), and electron capture negative ionization (ECNI) modes, combined with high-resolution mass spectrometry. This approach combines the separation capacity of GC × GC, detailed EI mass spectral libraries, the softness of PCI, and the selectivity of ECNI. Switching between ionization modes without any hardware change allowed to increase the information capacity and reliability of analysis. The structural elucidation becomes easier and more reliable due to the detection of molecular ions in PCI and ECNI modes with corresponding extensive fragmentation in EI, while the ECNI mode improves about 100 times the detection limits for environmentally relevant halogenated and nitro compounds. Overall, a notable enhancement of the analytical capabilities for both targeted and non-targeted purposes is achieved.

如今，优先和新兴污染物的数量已超过数千。因此，使用经典的气相色谱-质谱（GC-MS）监测数千种化合物是一项艰巨的任务。因此，通常会进行初步的非目标筛查以鉴定最相关的污染物。在这里，我们通过二维气相色谱（GC×GC），采用包括电子电离（EI），正化学电离（PCI）在内的电离方法，对来自北极，法国，智利和俄罗斯的雪，雨水和云水的复杂环境样品进行了分析。 ）和电子捕获负电离（ECNI）模式，并结合了高分辨率质谱。该方法结合了GC×GC的分离能力，详细的EI质谱库，PCI的柔软性和ECNI的选择性。在不更改任何硬件的情况下，在电离模式之间切换可以增加信息容量和分析的可靠性。由于在PCI和ECNI模式下检测到分子离子并在EI中有相应的广泛断裂，结构解析变得更容易，更可靠，而ECNI模式将环境相关的卤代和硝基化合物的检测限提高了约100倍。总体而言，针对目标和非目标目的的分析能力均得到了显着提高。而ECNI模式将环境相关的卤化和硝基化合物的检测限提高了约100倍。总体而言，针对目标和非目标目的的分析能力均得到了显着提高。而ECNI模式将环境相关的卤代和硝基化合物的检测限提高了约100倍。总体而言，针对目标和非目标目的的分析能力均得到了显着提高。