Caffeine and glucosamine mobility shifts by adduction with 2‐butanol depended on interaction energy, charge delocalization, and steric hindrance in ion mobility spectrometry

Ion mobility spectrometry (IMS) is an analytical technique that separates gas‐phase ions drifting under an electric field according to their size to charge ratio. We used electrospray ionization‐drift tube IMS coupled to quadrupole mass spectrometry to measure the mobilities of glucosamine (GH+) and...

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Bibliographic Details
Published in:Journal of mass spectrometry. 2017-12, Vol.52 (12), p.823-829
Main Authors: Meza‐Morelos, Dairo, Fernandez‐Maestre, Roberto
Format: Article
Language:English
Subjects:
2‐butanol
Adducts
Analytical methods
buffer gas modifier
Butanol
Caffeine
Clustering
dopant
Drift
Drift tubes
Energy charge
Ethyl lactate
Glucosamine
Hydrogen bonding
Hydrogen bonds
ion mobility spectrometry
Ionic mobility
Ionization
Ions
Lactate
Lactic acid
Mass spectrometry
Mass spectroscopy
Mobility
Quadrupoles
Scientific imaging
Spectroscopy
Steric hindrance
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Summary:Ion mobility spectrometry (IMS) is an analytical technique that separates gas‐phase ions drifting under an electric field according to their size to charge ratio. We used electrospray ionization‐drift tube IMS coupled to quadrupole mass spectrometry to measure the mobilities of glucosamine (GH+) and caffeine (CH+) ions in pure nitrogen or when the shift reagent (SR) 2‐butanol was introduced in the drift gas at 6.9 mmol m−3. Binding energies of 2‐butanol‐ion adducts were calculated using Gaussian 09 at the CAMB3LYP/6‐311++G(d,p) level of theory. The mobility shifts with the introduction of 2‐butanol in the drift gas were −2.4% (GH+) and −1.7% (CH+) and were due to clustering of GH+ and CH+ with 2‐butanol. The formation of GBH+ was favored over that of CBH+ because GBH+ formed more stable hydrogen bonds (83.3 kJ/mol) than CBH+ (81.7 kJ/mol) for the reason that the positive charge on CH+ is less sterically available than on GH+ and the charge is stabilized by resonance in CH+. These results are a confirmation of the arguments used to explain the drift behavior of these ions when ethyl lactate SR was used (Bull Kor Chem Soc 2014, 1023–1028). This study is a step forward to predict IMS separations of overlapping peaks in IMS spectra, simplifying a procedure that is trial and error by now.
ISSN:1076-5174
1096-9888
DOI:10.1002/jms.4026