Portable Mass Spectrometer Introduction Technology Based on Membrane Continuous Introduction and Pulse Introduction

Aiming to the inlet efficiency of domestic portable mass spectrometer which could keep vacuum degree, the membrane continuous introduction and pulse introduction technology were researched. Based on the testing apparatus of membrane and pulse introduction, the experiment was carried out with the xylene standard under the conditions of different temperature, different introduction flow and different pulse frequency. Using domestic produced membrane replaced imported membrane which was used in the injection valve of Hapsite, and their performance was compared under the conditions of same temperature and different introduction flow. In the membrane continuous introduction experiment, when the membrane temperature was set at 40 ℃, compared with the intensity of signal at 100 mL/min, the intensity of signal at 200 mL/min and 300 mL/min were improved by 40.7% and 85.5%, respectively. When the introduction flow was set at 300 mL/min, compared with the response time and peak tailing at 40 ℃, the response time was shortened by 24.1% and the peak tailing was reduced by 63.6% at 80 ℃. In the two kinds of membrane comparing experiment, keeping the temperature constant, the gap between domestic membrane and imported membrane could be narrowed by enhancing the introduction flow. The intensity gap was reduced by 68.9% and the peak tailing gap was reduced by 93.8% when the introduction flow was enhanced from 100 mL/min to 300 mL/min. In the pulse introduction experiment, when the membrane temperature was set at 40 ℃ and the introduction flow was set at 100 mL/min, compared with the intensity of signal at 1 Hz (pulse frequent), the intensity of signals at 5 Hz and 10 Hz were improved by 48.2% and 55.9%, and the response time at 10 Hz was shortened by 5.6% compared with the response time at 1 Hz, and the peak tailing at 10 Hz was improved by 7.8% compared with the peak tailing at 1 Hz, and the reason was that the membrane desorption process was mainly influenced by temperature, and when the temperature stays the same, the introduction quantity increase could result in extending the desorption process. The experimental results showed that improving temperature and introduction flow could strengthen the intensity of signal, shorten response time and reduce peak tailing. It could not only keep the vacuum degree, but also improve the intensity of ions and cut down the response time on the basis of strengthening the pulse voltage when using the pulse introduction. © 2018, Editorial Board of Journal of Chinese Mass Spectrometry Society. All right reserved.