Buffer gas additives (modifiers/shift reagents) in ion mobility spectrometry: Applications, predictions of mobility shifts, and influence of interaction energy and structure

2018 ◽  
Vol 53 (7) ◽  
pp. 598-613 ◽  
Author(s):  
Roberto Fernandez-Maestre
Keyword(s):  
Interaction Energy ◽  
Ion Mobility Spectrometry ◽  
Ion Mobility ◽  
Buffer Gas ◽  
Shift Reagents

scholarly journals Ion-shift reagent binding energy and the shift-mass correlation in ion mobility spectrometry

2022 ◽  
Author(s):  
Roberto Fernandez-Maestre ◽  
Mahmoud Tabrizchi ◽  
Dairo Meza-Morelos
Keyword(s):  
Molecular Weight ◽  
Binding Energy ◽  
Interaction Energy ◽  
Ion Mobility Spectrometry ◽  
Ion Mobility ◽  
Drift Time ◽  
Shift Reagent ◽  
False Positives ◽  
Time Shift ◽  
Buffer Gas

Ion mobility spectrometry is widely used for the detection of illegal substances and explosives in airports, ports, custom, some stations and many other important places. This task is usually complicated by false positives caused by overlapping the target peaks with that of interferents, commonly associated with samples of interest. Shift reagents (SR) are species that selectively change ion mobilities through adduction with analyte ions when they are introduced in IMS instruments. This characteristic can be used to discriminate false positives because the interferents and illegal substances respond differently to SR depending on the structure and size of analytes and their interaction energy with SR. This study demonstrates that ion mobility shifts upon introduction of SR depend, not only on the ion masses, but on the interaction energies of the ion:SR adducts. In this study, we introduced five different SRs using ESI-IMS-MS to study the effect of the interaction energy and size on mobility shifts. The mobility shifts showed a decreasing trend as the molecular weight increased for the series of compounds ethanolamine, valinol, serine, threonine, phenylalanine, tyrosine, tributylamine, tryptophan, desipramine, and tribenzylamine. It was proved that the decreasing trend was partially due to the inverse relation between the mobility and drift time and hence, the shift in drift time better reflects the pure effect of SR on the mobility of analytes. Yet the drift time shift exhibited a mild decrease with the mass of ions. Valinol pulled out from this trend because it had a low binding energy interaction with all the SR and, consequently, its clusters were short-lived. This short lifetime produced fewer collisions against the buffer gas and a drift time shorter compared to those of ions of similar molecular weight. Analyte ion:SR interactions were calculated using Gaussian. IMS with the introduction of SR could be the choice for the free-interferents detection of illegal drugs, explosives, and biological and warfare agents. The suppression of false positives could facilitate the transit of passengers and cargos, rise the confiscation of illicit substances, and save money and distresses due to needless delays. Keywords: Adduction, ion mobility spectrometry, mass spectrometry, shift reagent, valinol, buffer gas modifier

scholarly journals On the Separation of Enantiomers by Drift Tube Ion Mobility Spectrometry

2021 ◽  
Author(s):  
Roberto Fernandez-Maestre ◽  
Markus Doerr
Keyword(s):  
Ion Mobility Spectrometry ◽  
Ion Mobility ◽  
Gas Flow ◽  
Drift Time ◽  
Chiral Selector ◽  
Buffer Gas ◽  
Chiral Drugs ◽  
Experimental Conditions ◽  
Chiral Selectors ◽  
Racemic Mixtures

<p><a>Racemic mixtures of twelve common </a>a-amino acids and three chiral drugs were tested for the separation of their enantiomers by ion mobility spectrometry (IMS)-quadrupole mass spectrometry (MS). Separations were tested by introducing chiral selectors in the mobility spectrometer buffer gas. (R)-α-(trifluoromethyl) benzyl alcohol, (R)-tetrahydrofuran-2-carbonitrile, (L)-ethyl lactate, methyl (S)-2-chloropropionate, and the R and S enantiomers of 2-butanol and 1-phenyl ethanol were evaluated as chiral selectors. Experimental conditions were varied during the tests including buffer gas temperature, concentration, and type of chiral selectors, analyte concentration, electrospray voltage, electrospray (ESI) solvent pH, and buffer gas flow. The individual enantiomers yielded different drift times for periods of up to 8 hours in a few experiments; such drift times were sufficiently different (~ 0.3 ms) to partially resolve the enantiomers in racemic mixtures, but these mixtures always yielded a single mobility peak at the experimental conditions tested with a drift time similar to that of one of the enantiomers. Energy calculations of the chiral selector –ion interactions showed that these separations are unlikely using 2-butanol as chiral selector but they might be feasible depending on the nature of chiral selectors and the type of enantiomers.</p>

Deprotonation effect of tetrahydrofuran-2-carbonitrile buffer gas dopant in ion mobility spectrometry

2016 ◽  
Vol 30 (11) ◽  
pp. 1332-1338 ◽  
Author(s):  
Roberto Fernandez-Maestre ◽  
Dairo Meza-Morelos ◽  
Ching Wu
Keyword(s):  
Ion Mobility Spectrometry ◽  
Ion Mobility ◽  
Buffer Gas

scholarly journals On the Separation of Enantiomers by Drift Tube Ion Mobility Spectrometry

2021 ◽  
Author(s):  
Roberto Fernandez-Maestre ◽  
Markus Doerr
Keyword(s):  
Ion Mobility Spectrometry ◽  
Ion Mobility ◽  
Gas Flow ◽  
Drift Time ◽  
Chiral Selector ◽  
Buffer Gas ◽  
Chiral Drugs ◽  
Experimental Conditions ◽  
Chiral Selectors ◽  
Racemic Mixtures

<p><a>Racemic mixtures of twelve common </a>a-amino acids and three chiral drugs were tested for the separation of their enantiomers by ion mobility spectrometry (IMS)-quadrupole mass spectrometry (MS). Separations were tested by introducing chiral selectors in the mobility spectrometer buffer gas. (R)-α-(trifluoromethyl) benzyl alcohol, (R)-tetrahydrofuran-2-carbonitrile, (L)-ethyl lactate, methyl (S)-2-chloropropionate, and the R and S enantiomers of 2-butanol and 1-phenyl ethanol were evaluated as chiral selectors. Experimental conditions were varied during the tests including buffer gas temperature, concentration, and type of chiral selectors, analyte concentration, electrospray voltage, electrospray (ESI) solvent pH, and buffer gas flow. The individual enantiomers yielded different drift times for periods of up to 8 hours in a few experiments; such drift times were sufficiently different (~ 0.3 ms) to partially resolve the enantiomers in racemic mixtures, but these mixtures always yielded a single mobility peak at the experimental conditions tested with a drift time similar to that of one of the enantiomers. Energy calculations of the chiral selector –ion interactions showed that these separations are unlikely using 2-butanol as chiral selector but they might be feasible depending on the nature of chiral selectors and the type of enantiomers.</p>

scholarly journals Exploring Crown Ethers as Shift Reagents for Ion Mobility Spectrometry

2006 ◽  
Vol 78 (19) ◽  
pp. 6792-6800 ◽  
Author(s):  
Amy E. Hilderbrand ◽  
Sunnie Myung ◽  
David E. Clemmer
Keyword(s):  
Crown Ethers ◽  
Ion Mobility Spectrometry ◽  
Ion Mobility ◽  
Shift Reagents
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