New Progress Made in Ultra-high Sensitive Ion Mobility Spectrometry of Dalian Institute of Chemicals

Recently, the rapid separation and detection research group of Dalian Institute of Chemical Physics, Chinese Academy of Sciences (Group 102), Chen Chuang and Li Haiyang have successfully developed a highly sensitive ion mobility spectrum using pulsed ion enrichment technology. The relevant results were published in the American Chemical Society, Analytical Chemistry (doi: 10.1021/acs.analchem.5b01737).

Ion mobility spectrometry, as a highly sensitive and rapid separation detection technique, plays an important role in explosive detection, chemical warfare agent early warning and other fields. However, to ensure acceptable resolving power, ion mobility spectrometry usually uses 200 Î¼s ion gates every 20 ms to inject ions into ion transport tubes for separation and detection. This working mode has extremely low utilization efficiency of the ions generated by the ion source, which is only 1%, which is not conducive to the further improvement of the ion mobility spectrum sensitivity.

To increase the efficiency of the use of ions in the ion source, the researchers applied a high-voltage pulse synchronized with the ion door opening pulse on the electrode between the ion source and the ion gate. During the ion gate opening time interval, the high voltage pulse rapidly increases the electric field intensity of the ionization zone by 10 to 20 times, and the ions driving the ion gate enter the ion transport tube through the ion gate. The experimental results show that the technology can increase the ion use efficiency in the ion source from the original 1% to 20% under the premise of ensuring the original resolution of the ion mobility spectrum, greatly improving the sensitivity. For example, the detection limit of the Sarin toxic agent mimetic DMMP was reduced from the original 5 ppbv to 200 pptv, and the sensitivity was increased 25-fold. The technology is simple to implement and does not require any hardware improvements to existing ion transfer tubes.

This study is another new development after the early development of negative ion photoionization sources (Anal. Chem., 2010, 82, 4151). The above research work has been funded by the National Natural Science Foundation of China.

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