Abstract:The isomer ratio determination of a selenium-containing metabolite produced by Se-rich yeast was performed. Electrospray ionization and ion mobility mass spectrometry (IM-MS) were unsuccessfully used in order to resolve the isomers according to their collisional cross section (CCS) difference. The isomer ratio determination of 2,3-dihydroxypropionylselenocystathionine was performed after multidimensional liquid chromatography preconcentration from a water extract of Se-rich yeast using preparative size exclusi… Show more
“…The separation mechanism in these experiments was similar to those studied in this review in that they encompass the selective change in the ions' CCSs. However, the crown ethers were injected in the aqueous phase previous to IMS‐MS, not in the buffer gas, and the clusters did not establish equilibria in the buffer gas because the cluster formation was irreversible due to the strong ion‐SR interaction.…”
Section: Applications Of Mobility Shifts Upon Injection Of Buffer Gasmentioning
confidence: 69%
“…This methodology is advantageous in that the buffer gas is saturated with the SRs leading to equilibria between analyte ions and SR molecules producing clear and sharp peaks of analyte ion‐SR clusters.In other application, the isomer ratio determination of a selenium‐containing metabolite was performed after multidimensional liquid chromatography preconcentration from a yeast water extract. An SR, 4′‐nitrobenzo‐15‐crown‐5 ether, was added to the ESI solution to increase the CCS of one of the isomers by the formation of a stable host–guest system and separate the isomers . Kune et al also used crown ethers as SRs in IMS to separate valine and proline protonated ions because the crown ethers were selective to the primary amino group in valine, absent in proline, decreasing valine's mobility: …”
Section: Applications Of Mobility Shifts Upon Injection Of Buffer Gasmentioning
confidence: 99%
“…These studies also answer fundamental questions of science. Ion mobility spectrometry experiments introducing SRs in the buffer gas are used to determine isomer ratio and, in the future, may be directed to understand IHBs, to demonstrate their formation and measure their energy and explain the effect of size, steric hindrance, proton affinity, IHB energy, and inductive effects on clustering, relevant to understand the growing of particles by nucleation in ambient air. Other applications solve technological issues such as in the separation of overlapping peaks in IMS spectra in the food, beverage, pharmaceutical, and other industries, important for cleaning verification requirements.…”
Section: Importance Of Selective Ion Mobility Shifts Produced By Srsmentioning
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. Ion mobility spectrometry separates ions in the gas-phase drifting under an electric field according to their size to charge ratio. Ion mobility spectrometry 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 2 different conditions, in pure buffer gas or when shift reagents (SRs) are introduced in this gas, providing 2 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.
“…The separation mechanism in these experiments was similar to those studied in this review in that they encompass the selective change in the ions' CCSs. However, the crown ethers were injected in the aqueous phase previous to IMS‐MS, not in the buffer gas, and the clusters did not establish equilibria in the buffer gas because the cluster formation was irreversible due to the strong ion‐SR interaction.…”
Section: Applications Of Mobility Shifts Upon Injection Of Buffer Gasmentioning
confidence: 69%
“…This methodology is advantageous in that the buffer gas is saturated with the SRs leading to equilibria between analyte ions and SR molecules producing clear and sharp peaks of analyte ion‐SR clusters.In other application, the isomer ratio determination of a selenium‐containing metabolite was performed after multidimensional liquid chromatography preconcentration from a yeast water extract. An SR, 4′‐nitrobenzo‐15‐crown‐5 ether, was added to the ESI solution to increase the CCS of one of the isomers by the formation of a stable host–guest system and separate the isomers . Kune et al also used crown ethers as SRs in IMS to separate valine and proline protonated ions because the crown ethers were selective to the primary amino group in valine, absent in proline, decreasing valine's mobility: …”
Section: Applications Of Mobility Shifts Upon Injection Of Buffer Gasmentioning
confidence: 99%
“…These studies also answer fundamental questions of science. Ion mobility spectrometry experiments introducing SRs in the buffer gas are used to determine isomer ratio and, in the future, may be directed to understand IHBs, to demonstrate their formation and measure their energy and explain the effect of size, steric hindrance, proton affinity, IHB energy, and inductive effects on clustering, relevant to understand the growing of particles by nucleation in ambient air. Other applications solve technological issues such as in the separation of overlapping peaks in IMS spectra in the food, beverage, pharmaceutical, and other industries, important for cleaning verification requirements.…”
Section: Importance Of Selective Ion Mobility Shifts Produced By Srsmentioning
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. Ion mobility spectrometry separates ions in the gas-phase drifting under an electric field according to their size to charge ratio. Ion mobility spectrometry 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 2 different conditions, in pure buffer gas or when shift reagents (SRs) are introduced in this gas, providing 2 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.
“…An SR is a modifier additive that changes the CCS of a target ion by the formation of host‐guest systems and leading to a shift in the ion mobility coefficient (generally to lower values). SR can be used as a drift gas modifier in the IMS cell or as a complexing agent (i. e. a ligand) in solution added before the sample injection . In addition to avoiding false positives, the use of SR could also increase the confidence level of ion detection by checking the ion mobility values of the target ion before and after coordination with the SR. For instance, one of the well‐known SR is the 18‐crown‐6 ether.…”
Ion mobility spectrometry (IMS) is a gas-phase separation technique based on ion mobility differences in an electric field. It is largely used for the detection of specific ions such as small molecule explosives. IMS detection system includes the use of e. g. a Faraday cupor mass spectrometry (MS). The presence of interfering ion signals in standalone IMS may lead to the detection of false positives or negatives due to e. g. lacking resolving power. In this case, selective mobility shifts obtained using shift reagents (SR), i. e. ligands complexing a specific target, can bring help. The effectiveness of an SR strategy relies on the SR-target ion selectivity. The crucial step lies in the SR design. The aim of this paper is to present an efficient interplay of experimental ion mobility mass spectrometry (IMMS) and predictive computational chemistry using various levels of computational efforts for rationally designing target-specific SR. Mass spectrometry is used to evaluate the efficiency of the SR selectivity with identification and semi-quantification of free and complexed ions. Minimal computational efforts allow the design of the SR, predicting the SR-target ion relative stabilities, and predicting the ion mobility shifts. We demonstrate our approach using crown ethers and β-cyclodextrin to selectively shift interfering perchlorate, amino acids and diaminonaphthalene isomers. We also release the software ParsIMoS for the straightforward use of ion mobility calculator IMoS.
“…Paglia and coworkers demonstrated the utility of incorporating such mobility information into comparative metabolomics workflows and described searchable collision cross section databases to aid ion identification. 40 One recent study used the structural heterogeneity of phosphorylated peptide ions doped into tryptic digests to link precursor ions with those formed upon neutral loss of H 3 PO 4 resulting from collisional activation at the back of the drift tube. 37 Similarly, experiments recently showed that mobility measurements could be used with other analytical information (LC retention time and precursor and fragment ion masses) to distinguish isomeric species in complex mixtures obtained from natural products 38 as well as to identify potential biomarkers in comparative metabolomics analyses 39 .…”
Over the last decade, the field of ion mobility-mass spectrometry (IM-MS) has experienced dramatic growth in its application toward ion structure characterization. Enabling advances in instrumentation during this time period include improved conformation resolution and ion sensitivity. Such advances have rendered IM-MS a powerful approach for characterizing samples presenting a diverse array of ion structures. The structural heterogeneity that can be interrogated by IM-MS techniques now ranges from samples containing mixtures of small molecules exhibiting a variety of structural types to those containing very large protein complexes and subcomplexes. In addition to this diversity, IM-MS techniques have been used to probe spontaneous and induced structural transformations occurring in solution or the gas phase. To support these measurement efforts, significant advances have been made in theoretical methods aimed at translating IM-MS data into structural information. These efforts have ranged from providing more reliable trial structures for comparison to the experimental measurements to dramatically reducing the time required to calculate collision cross sections for such structures. In this short review, recent advances in developments in IM-MS instrumentation, techniques, and theory are discussed with regard to their implications for characterization of gas- and solution-phase structural heterogeneity.
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