A simple strategy for d-l malic acid recognition and quantification using trapped ion mobility spectrometry

Identification and quantification of bipyridyl dicarboxylic acid isomers by ion mobility spectrometry

The identification of positional isomers is of interest because different isomers have different chemical or biological functions and applications. The analysis of positional isomers is sometimes challenging since they have similar chemical structures and properties. For example, the analysis of mass cannot identify different positional isomers because they have identical mass-to-charge ratios and show a single mass peak in mass spectrometry. In this study, an efficient and simple qualitative and quantitative analytical method for differentiating 2,2'-bipyridine-3,3'-dicarboxylic acid (3,3'-BDA), 2,2'-bipyridine-4,4'-dicarboxylic acid (4,4'-BDA), and 2,2'-bipyridine-5,5'-dicarboxylic acid (5,5'-BDA) was developed by using ion mobility spectrometry (IMS). The results revealed that the three BDA isomers formed non-covalent complexes with cyclodextrins (CDs) and Mg2+ ions in the gas phase: [β-CD+3,3'/4,4'/5,5'-BDA+Mg]2+ and [γ-CD+3,3'/4,4'/5,5'-BDA+Mg]2+, which were distinguished by measuring the mobility of the complexes because of their spatial conformational differences. The peak-to-peak resolution (Rp-p) values of the three isomers of [γ-CD+3,3'/4,4'/5,5'-BDA+Mg]2+ reached 2.983 and 2.892, respectively. The conformations of the ternary complexes simulated by the theoretical calculations revealed the different interactions and shapes of the stereoisomers, and the predicted results agreed with the experimental results. Simultaneously, further studies on the collisional dissociation of the ternary complexes revealed that the dissociation energies of the different complex ions varied were different owing to the diverse different conformations. Finally, the relative quantitative analysis of the different isomers in mixed samples was performed and satisfactory linearity results (R2 > 0.99) were obtained. Thus, an effective analytical method was proposed for the identification and quantification of BDA isomers without chemical derivatization, offering a promising approach for the identification of similar derivatives or positional isomers that could be applied in various fields including chemicals and pharmaceuticals.

Overlapping peak separation algorithm for ion mobility spectra based on multistrategy JAYA

RATIONALE

In the field of separation science, ion mobility spectrometry (IMS) plays an important role as an analytical tool. However, the lack of sufficient structural resolution is a common problem in qualitative and quantitative analysis using IMS. A method is needed to solve the problem of overlapping peaks caused by insufficient resolution.

METHODS

The method uses multiple strategies to more effectively use population information to balance exploration and exploitation capabilities, prevent local optimization, accurately resolve overlapping peaks, quickly obtain optimal spectral peak model coefficients, and accurately identify compounds.

RESULTS

Multistrategy JAYA algorithm's (MSJAYA) performance is compared with improved particle swarm optimization (IPSO), dynamic inertia weight particle swarm optimization (DIWPSO), and multiobjective dynamic teaching-learning-based optimization (MDTLBO). The analysis shows that MSJAYA's maximum separation error is within 0.6%, a level of accuracy not guaranteed by the other algorithms. In addition, the separation error fluctuates within a much smaller range, demonstrating MSJAYA's superior robustness.

CONCLUSIONS

Compared with other overlapping peak separation algorithms, MSJAYA is more applicable because no special parameters are used. The method allows fast deconvolution analysis of strong overlapping peaks with multiple components, which greatly improves the resolution of IMS.

A cyclodextrin-based reagent for cis/trans-geometrical isomers separation by mobility measurements and chemical calculations

Identification of cis/trans-carbon-carbon double-bond (CC) isomers remain challenging. Herein, a simple and rapid method for the separation and analysis of cis/trans-maleic acid (MA) and aconitic acid (AA) using Trapped Ion Mobility Spectrometry (TIMS) was developed. α-, β-, γ-cyclodextrin (CD) were served as the separation reagent, slight difference in mobility separation was obtained by [CD-MA/AA-H]^-. Specially, with the addition of divalent metal ion (G²⁺) as coordination metal ion, the separation effect was much increased by [CD-MA/AA + G-H]⁺, and α-CD has better mobility separation effect than β-/γ-CD. Moreover, chemical calculations revealed the binary and ternary complexes are in the inclusion forms, and microscopic interactions between cis/trans-MA/AA, CDs, and G²⁺ are somewhat different that making their mobility separation. Finally, quantifications of cis/trans-isomers were analyzed in food samples, with good linearity (R² > 0.99) and recoveries obtained from 87.25 % to 100.73 %.

Identification of Bi-2-naphthol and Its Phosphate Derivatives Complexed with Cyclodextrin and Metal Ions Using Trapped Ion Mobility Spectrometry

The separation of chiral enantiomers has gained increasing importance in many research fields, becoming a major research hotspot. 1,1'-Bi (2-naphthol) (BINOL) and 1,1'-binaphthyl-2,2'-diyl hydrogen phosphate (BNP) are referred to as atropisomer chiral molecules, which are essential chiral catalysts and intermediates in several reactions. In this work, BINOL and BNP atropisomers are separated and identified using trapped ion mobility spectrometry (TIMS) to monitor the different mobilities of their derivative complexes. The latter are obtained by the simple mixing of BINOL/BNP, cyclodextrin (CD), and the metal ions through noncovalent interactions. The results indicate that the enantiomer complexes of BINOL/BNP can be separated with a certain specificity, showing that R-, S-BINOL can be separated by the ternary complexes of [BINOL+γ-CD + Rb]⁺, [BINOL+γ-CD + Cu-H]⁺, and [BINOL+β-CD + Cu-H]⁺ based on the difference in their mobility; similarly, the R-, S-BNP enantiomer can be isolated by the formed ternary complexes of [BNP+α-CD + Ba-H]⁺, [BNP+β-CD + Co-H]⁺, [BNP+β-CD + Ca-H]⁺, [BNP+β-CD + Cu-H]⁺, [BNP+β-CD + Fe-H]⁺, [BNP+β-CD + Li]⁺, and [BNP+β-CD + Sr-H]⁺. Furthermore, the peak separation rate (R_p-p) of the complexes was calculated, with the R_p-p of the three enantiomers of BINOL being 1.130 and the R_p-p of the seven complexes of BNP reaching 2.089. At last, the different survival yields for the collision energies were found for the enantiomer complexes, revealing the rigid structural differences in the stereospecificity of the enantiomer complexes that result in the separation by the TIMS. Additionally, due to the advantages of simple operation, fast speed, and high sensitivity and because chemical derivatization and chromatographic separation are not required, the developed method can provide a promising and powerful strategy for the separation and identification of binaphthyl derivatives or even other enantiomers of the reaction intermediates.

Distinction of chiral penicillamine using metal-ion coupled cyclodextrin complex as chiral selector by trapped ion mobility-mass spectrometry and a structure investigation of the complexes

Penicillamine (Pen) is a common chiral drug that is obtained from penicillin. Between the two enantiomers of Pen, only D-Pen can be used to treat cystinuria and rheumatoid arthritis while L-Pen is toxic. Therefore, it requires great efforts for the research of the rigorous analysis and distinction of the two enantiomers. The non-covalent combination of chiral molecules and chiral selectors (CSs) has been proved as a unique strategy for chiral distinction by ion mobility spectrometry in coupling with -mss spectrometry (IM-MS). Here, we developed a simple method to distinguish D, L-Pen by using special CSs for IM-MS separation. The CSs utilized here include cyclodextrins (CD) and linear chain oligosaccharides plus metal ions. We found that non-covalent complexes [Pen+β-CD + Li]⁺ could be easily formed by electrospray ionization of the mixture of the solution, and the chirality of Pen could be effectively recognized by measuring their mobilities due to the different collision cross collision sections of [D-Pen+β-CD + Li]⁺ and [L-Pen+β-CD + Li]⁺. A detailed analysis of [Pen+β-CD + Li]⁺ was then conducted by the optical rotation measurements and NMR experiments to reveal their structural differences. Furthermore, DFT calculation showed the differences of molecular conformation between the complexes. The results provide a new powerful method for fast analysis and recognition of chirality of Pen compounds by IM-MS.