Implications of Blanc’s Law for Use in Trapped Ion Mobility Spectrometry

Abstract

Blanc’s Law has served as a way to predict the mobilities of ions in mixed drift gases for over 100 years yet has remained largely unexplored using newer ion mobility spectrometry (IMS) configurations, including traveling wave and trapped IMS (TIMS) systems. Here, we evaluate a drift-tube IMS (DTIMS) and compare it to a similar set of experiments performed in TIMS. We found that Blanc’s Law can be applied in a DTIMS to determine the mobility of an analyte in the minor gas component of a ternary mixed drift gas system within 2% error. Additionally, the calibration procedure for TIMS to convert elution voltages into a mobility value corrects for significant deviations (>4%) from Blanc’s Law in the elution voltage domain. For the range of gas identities probed in this effort, up to an 11% error in calibrated mobilities was observed when using a gas mixture in the TIMS that differed from the gas used for the reference mobility. However, when the gas mixture within the TIMS was the same as the respective calibrant mobilities, calibration errors within the TIMS were as low as 0.01%. Interestingly, when probing the behavior of ions with argon-containing mixtures within the TIMS, the current accepted paradigm of elution voltage being proportional to inverse mobilities in TIMS calibrations procedures was shown to deviate substantially from the trends observed with DTIMS measurements. With this initial effort, foundations for future mixed drift gas measurements in TIMS are set for expanded analyte classes and larger molecules.

Setting the Separation Factor α for Ketone Monomers and Dimers by the Use of Different Drift Gases

“…28,30,31 Changes in mobility have been observed for the reactant ions and for other ions in different gases. 19,32,21,23 A change of conformation or composition of the reactant ions due to a change in drift gas has not yet been reported. Therefore, it can be assumed that different drift gases only change the mobility due to influences caused by the neutral drift gas itself.…”

“…Blanc's law has been used in combination with IMS in different instances and contexts. 17,23,24 The ionization in stand-alone IMS devices depends on the formation of water clusters and their interaction with the gaseous analyte, forming charged particles that can then be manipulated by the electric field. These water clusters are called reactant ions and are also detected by IMS and displayed as a peak.…”

Spatial and Spectral Evolution of Laser Induced Plasma on / near the Surface of an Aqueous Solution

“…As we know, air is a mixture of gases composed of approximately 78% nitrogen, 21% oxygen, 0.9% argon, and the rest being carbon dioxide and several trace gases (Naylor et al 2021). Furthermore, depending on humidity and temperature, a small amount of water vapor is also present.…”