Isomeric differentiation and quantification of α, β-amino acid-containing tripeptides by the kinetic method: alkali metal-bound dimeric cluster ions

of N-phenylbenzamide and N-phenylcinnamide. Loss of LiOH was essentially the sole fragmentation reaction observed for the former. For the latter, both losses of LiOH and H 2 O were discovered. The presence of electron-donating substituents of the phenyl ring of these compounds was found to facilitate elimination of LiOH, while that loss was retarded by electron-withdrawing substituents. Proposed fragment ion structures were supported by elemental compositions deduced from ultrahigh resolution Fourier transform ion cyclotron resonance tandem mass spectrometry (FTICR-MS/MS) m/z value determinations. Density functional theory-based (DFT) calculations were performed to evaluate potential mechanisms for these reactions.

mentioning

confidence: 99%

Gas Phase Chemistry of Li⁺with Amides: the Observation of LiOH Loss in Mass Spectrometry

Guo

Zhou

Liu

et al. 2012

“…A related thought process forms the basis of Cooks' kinetic method, perhaps the most widely applied chiral mass spectrometric technique [16][17][18][39][40][41][42][43][44][45]. This method measures the dissociation rates of cluster ions composed of a metal, chiral reference, and analyte of interest.…”

Section: Conventional Kinetic Methodsmentioning

confidence: 99%

Complete Hexose Isomer Identification with Mass Spectrometry

Nagy

Pohl

2015

Abstract. The first analytical method is presented for the identification and absolute configuration determination of all 24 aldohexose and 2-ketohexose isomers, including the D and L enantiomers for allose, altrose, galactose, glucose, gulose, idose, mannose, talose, fructose, psicose, sorbose, and tagatose. Two unique fixed ligand kinetic method combinations were discovered to create significant enough energetic differences to achieve chiral discrimination among all 24 hexoses. Each of these 24 hexoses yields unique ratios of a specific pair of fragment ions that allows for simultaneous determination of identification and absolute configuration. This mass spectrometric-based methodology can be readily employed for accurate identification of any isolated monosaccharide from an unknown biological source. This work provides a key step towards the goal of complete de novo carbohydrate analysis.

“…As a matter of fact, most of them did not show any tendency to fragment even at high collision energies (up to 40 eV, lab frame) (path a in Scheme 1). This behavior is rather unusual in view of the ability of similar metal bound adducts to readily release neutral fragments when collisionally excited [39][40][41]. However, it should be considered that the excited ions have a definite time to decompose in the collision cell.…”

Section: Structure and Dynamics Of The [M•k•ycooh] + Complexesmentioning

confidence: 97%

Contact Ion Pairs on a Protonated Azamacrocycle: the Role of the Anion Basicity

Fraschetti

Filippi

Crestoni

et al. 2016