Institute of Electrical Engineering and Measurement Technology, Department of Sensors and Measurement Technology, Leibniz University Hannover, Appelstr. 9A, Hannover 30167, Germany.
Institute of Electrical Engineering and Measurement Technology, Department of Sensors and Measurement Technology, Leibniz University Hannover, Appelstr. 9A, Hannover 30167, Germany.
J Chromatogr A. 2023 Nov 22;1711:464453. doi: 10.1016/j.chroma.2023.464453. Epub 2023 Oct 14.
In this paper, we present a new electron capture detector based on a compact X-ray tube (X-ECD) for electron generation by soft X-ray radiation instead of using a radioactive source. ECDs are commonly used in many laboratories as standard GC detectors since their invention in the 1950s, especially for highly sensitive detection of halogenated substances, pesticides or other environmental pollutants. However, due to unsatisfactory alternatives, many ECDs are still used with radioactive β-emitters, which is difficult and expensive in most applications today due to legal restrictions. The new X-ECD contains a small X-ray tube for generating free electrons by ionizing the carrier gas like in radioactive ECDs. Thus, no additional dopants or special gases are required. The X-ECD has limits of detection in the ppt range and shows linearity over a wide concentration range. Furthermore, the used X-ray tube shows good long-term stability. So far, we have operated the X-ray tube continuously for about one year without notable degradation. However, in case of future degradation, the X-ECD can still be operated with the same sensitivity by simple adjusting the set point current in constant current mode. This makes calibration robust against possible degradation of the X-ray tube. In combination with a conventional gas chromatograph, the X-ECD is able to detect halogenated hydrocarbons and even low volatile pesticides without any peak distortion such as tailing. Thereby a minimum detectability in the upper fg/µL range for Lindane was reached, which is similar when compared to radioactive ECDs.
在本文中，我们提出了一种新的电子俘获检测器，它基于一个紧凑型 X 射线管（X-ECD），通过软 X 射线辐射产生电子，而不是使用放射性源。ECD 自 20 世纪 50 年代发明以来，在许多实验室中被广泛用作标准 GC 检测器，特别是用于高度敏感地检测卤代物质、农药或其他环境污染物。然而，由于不理想的替代品，许多 ECD 仍然使用放射性 β 发射器，由于法律限制，在当今大多数应用中，这既困难又昂贵。新的 X-ECD 包含一个小的 X 射线管，用于通过像放射性 ECD 那样使载气电离来产生自由电子。因此，不需要额外的掺杂剂或特殊气体。X-ECD 的检测限在 ppt 范围内，并在较宽的浓度范围内显示出线性。此外，所使用的 X 射线管具有良好的长期稳定性。到目前为止，我们已经连续操作 X 射线管大约一年，没有明显的降级。然而，如果将来出现降级，X-ECD 仍然可以通过在恒流模式下简单调整设定点电流来以相同的灵敏度运行。这使得校准对 X 射线管的可能降级具有鲁棒性。与传统的气相色谱仪结合使用，X-ECD 能够检测卤代烃，甚至是低挥发性的农药，而不会出现任何峰形扭曲，如拖尾。从而达到了林丹的上 fg/µL 范围的最小检测限，与放射性 ECD 相比相似。
