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Structures of dopant and analytes 82x231mm (150 x 150 DPI)
Source publication
Rationale:
When dopants are introduced into the buffer gas of an ion mobility spectrometer, spectra are simplified due to charge competition.
Methods:
We used electrospray ionization to inject tetrahydrofuran-2-carbonitrile (F, 2-furonitrile or 2-furancarbonitrile) as a buffer gas dopant into an ion mobility spectrometer coupled to a quadrupole...
Similar publications
Ion mobility spectrometry (IMS) 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 obtain the mobilities of common amino acids, amines, valinol, atenolol, and the chemical standards tetramethylammonium ion (TMA),...
Citations
... 78 In these applications, the difference in proton affinity between the SR and analytes should be small enough to avoid deprotonation. 41 The introduction of SRs in the buffer gas in IMS to resolve overlapping peaks was reviewed by Puton et al 79 and Waraksa et al. 80 The ion-SR noncovalent interaction energies (E I ) may be calculated using E I = E cluster − (E SR + E protonated ion ) and proton affinities subtracting protonated ion energies from molecule energies. 95 Interaction energies of ion-SR clusters have been calculated using the GAMESS program 96 ...
Ion mobility spectrometry (IMS) is an analytical technique used for fast and sensitive detection of illegal substances in customs and airports, diagnosis of diseases through detection of metabolites in breath, fundamental studies in physics and chemistry, space exploration and many more applications. IMS separates ions in the gas‐phase drifting under an electric field according to their size to charge ratio. IMS disadvantages are false positives that delay transportation, compromise patient's health and other negative issues when IMS is used for detection. To prevent false positives, IMS measures the ion mobilities in two different conditions, in pure buffer gas or when shift reagents (SR) are introduced in this gas, providing two different characteristic properties of the ion and increasing the chances of right identification. Mobility shifts with the introduction of SRs in the buffer gas are due to clustering of analyte ions with SRs. Effective SRs are polar volatile compounds with free electron pairs with a tendency to form clusters with the analyte ion. Formation of clusters is favored by formation of stable analyte ion‐SR hydrogen bonds, high analytes' proton affinity and low steric hindrance in the ion charge while stabilization of ion charge by resonance may disfavor it. Inductive effects and the number of adduction sites also affect cluster formation. The prediction of IMS separations of overlapping peaks is important because it simplifies a trial and error procedure. Doping experiments to simplify IMS spectra by changing the ion‐analyte reactions forming the so‐called alternative reactant ions are not considered in this review and techniques other than drift tube IMS are marginally covered.
Electrospray ionization IMS coupled to quadrupole mass spectrometry was used to calculate the reduced ion mobilities of aspartame, cortisone, betamethasone, butylparaben, propylparaben and vanillin, a set of organic compounds used as drugs or food additives using 2,6-ditert-butylpyridine (DTBP) as a chemical standard. The K0’S of these compounds in the literature are either unavailable or unreliable. The importance of using chemical standards to calibrate the ion mobility scale and the use of correct experimental temperatures to calculate ion mobilities are stressed.
