Chemical standards in ion mobility spectrometry

Area of Science:

• Analytical Chemistry
• Physical Chemistry

Background:

• Reduced mobility (K(0)) values in ion mobility spectrometry (IMS) are critical for gas phase ion characterization.
• Discrepancies between literature and field-reported K(0) values are often attributed to buffer gas contamination.

Purpose of the Study:

• To investigate the impact of moisture and organic contaminants in buffer gas on the mobility of IMS standards and analytes.
• To identify strategies for improving the accuracy of K(0) measurements in IMS.

Main Methods:

• Ion mobility spectrometry directly coupled to mass spectrometry (IMS-MS).
• Utilized chemical standards including 2,4-Dimethylpyridine, 2,6-di-tert-butylpyridine (DTBP), and various tetraalkylammonium chlorides.
• Assessed the effect of controlled buffer gas contamination on ion mobility.

Main Results:

• IMS standard ions showed minimal mobility changes with low contamination levels.
• Analyte ion mobilities were significantly affected by contaminants, often decreasing due to ion-molecule cluster formation.
• Contaminants impacted mobility standards similarly to analytes, while instrument standards remained unaffected.

Conclusions:

• Accurate K(0) measurements require a dual-standard approach: an instrument standard for system calibration and a mobility standard to monitor buffer gas effects.
• Careful selection and use of both instrument and mobility standards are essential for reliable IMS data acquisition in diverse environmental conditions.