Effects of temperature and clustering on mobility of ions in carbon dioxide (original) (raw)

The effects of temperature and clustering on the mobility of ions drifting in C 0 2 at ambient pressure were studied by ion mobility spectrometry (IMS). A semiempirical procedure for obtaining quantitative data on the size of the cluster was applied. At 90 O C , about three C02 molecules, on average, clustered around protonated amine core ions. As the temperature was raised, the number of clustered molecules decreased, and above 200 O C , it was practically zero. A clear mass-mobility correlation was observed in the protonated aliphatic amines even at 90 O C. Protonated pyridine, picoline, lutidine, and collidine were unresolved at this temperature, but as the temperature was raised, resolution improved. On the whole, use of COz as a drift gas in IMS, although inferior in some cases, should not be precluded.