Comprehensive profiling of conjugated fatty acid isomers and their lipid oxidation products by two-dimensional chiral RP×RP liquid chromatography hyphenated to UV- and SWATH-MS-detection

Olfert, Matthias; Bäurer, Stefanie; Wolter, Marc; Buckenmaier, Stephan; Fuente, Edmundo Brito-de la; Lämmerhofer, Michael

doi:10.1016/j.aca.2022.339667

Cited by 16 publications

(6 citation statements)

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“…The second peak, in the near UV region, appeared when the concentration was above 0.5 mM, with a weaker absorbance and lower energy wavelength of 232 nm, with no significant bathochromic shifts. This second peak was reported in previous studies of conjugated fatty acids but in the visible domain of the electromagnetic spectrum 19,42,43 and not in unsaturated nonconjugated fatty acids (like oleic acid). 19 According to the available literature discussing NaOL adsorption on mineral surfaces, an additional peak should appear around 280 nm.…”

Section: Ultraviolet Spectra Of Reagentssupporting

confidence: 73%

Effect of (De-)protonation on the UV Spectra of Sodium Oleate: Experimental and Electronic Structure Investigation

Murhula

Arellano

Cook

et al. 2023

ACS Appl. Opt. Mater.

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Sodium oleate (NaOL), an anionic surfactant used in mineral processing, is challenging to quantify in aqueous solutions using UV spectroscopy. This study examined ultraviolet spectral shifts of sodium oleate with and without common pH regulators. Experimental results were supported by quantum chemical calculations at the CAM-B3LYP//6–31++G(d,p) level of theory. Two main absorbance peaks appeared in sequence, at 190 and 232 nm, corresponding to the π → π* and the n → π* electronic transitions of the CC double bond and COO– functional group, respectively. Under the typical concentration range used in adsorption and flotation studies, the first peak redshifted to reach λmax = 203 nm at 2 mM NaOL, while both solution deprotonation and protonation resulted in hypo/hyperchromicity. By influencing the electronic environment, acidic and alkaline treatments triggered a broadening and narrowing of the NaOL UV spectra. This difference in behavior was associated with the dissociative equilibrium of oleic acid, where protonation was favorable to molecular species, whereas deprotonation favored the ionic oleate species. The HOMO-LUMO excitation energies were higher in the protonated than in the deprotonated environment, explaining the broader spectra obtained experimentally in the former and higher reactivity in the latter. The peak disruptions give rise to significant discrepancies during quantitative measurements of NaOL in aqueous solutions, which may be managed by appropriate precautions and corrective techniques. These findings can be extended to systems similar to the oleate system and may guide experimental and data-processing procedures in UV spectrometry.

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Section: Ultraviolet Spectra Of Reagentssupporting

confidence: 73%

Effect of (De-)protonation on the UV Spectra of Sodium Oleate: Experimental and Electronic Structure Investigation

Murhula

Arellano

Cook

et al. 2023

ACS Appl. Opt. Mater.

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“…For example, CE 18:2 < +1O,−2H> is an oxidized metabolite that elutes 2 min before the unmodified CE 18:2 (Figure 3). By selecting a RT window of 0.3 min (22.0−22.3), the low IM resolution data used to acquire MS/MS data shows that a mixture of different isomers can be detected in different mobility regions (Figure 3C−D), indicating the formation of CE 18:2 <oxo≥ isomers at different positions (9,10,11). The potential isomers of CE 18:2 < +1O,−2H> were well discriminated by the HRDm.…”

Section: ■ Introductionmentioning

confidence: 99%

“…9 The combination of an amylose-based tris(3,5-dimethylphenylcarbamate) chiral column in the first dimension and a C18 RP column in the second dimension provided comprehensive orthogonal LC × LC analysis of oxylipins, however, at the cost of long analysis time (3 h per sample) and low sensitivity due to dilution effects. 10 Ion mobility spectrometry (IMS), a gas-phase technique separating ionized analytes based on the size, shape, and charge, has shown promising results in the separation of isobaric and isomeric lipids (e.g., sn-positions, cis/trans orientations, and R/S positions). 11 In addition to increasing the overall peak capacity of the analytical platform by coupling IMS to LC-HRMS, collision cross-section (CCS) values can be derived from the measured mobility and used to support untargeted annotation workflows.…”

Section: ■ Introductionmentioning

confidence: 99%

Investigating the Potential of Drift Tube Ion Mobility for the Analysis of Oxidized Lipids

da Silva,

Wölk,

Nepachalovich

et al. 2023

Anal. Chem.

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“…Because of the lower optimal speed of chiral analysis, the chiral dimension has mostly been used in the first dimension (chiral × achiral) in comprehensive 2D-LC, so far. Olfert et al used chiral × achiral for the profiling of saturated, unsaturated, and oxidized fatty acids without a derivatization step . Acquaviva et al separated the amino acids in honey samples using chiral × achiral 2D-LC using an active splitter pump in the modulator.…”

Section: Introductionmentioning

confidence: 99%

“…Olfert et al used chiral × achiral for the profiling of saturated, unsaturated, and oxidized fatty acids without a derivatization step. 20 Acquaviva et al separated the amino acids in honey samples using chiral × achiral 2D-LC using an active splitter pump in the modulator. This made it possible for the 1 D flow rate to be independent from the 2 D cycle and to regulate the transferred sample volume to the second dimension.…”

Section: ■ Introductionmentioning

confidence: 99%

Temperature Responsive × Fast Chiral Comprehensive Liquid Chromatography: a New 2D-LC Platform for Resolving Mixtures of Chiral Isomers

2023

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Chiral resolution of solutes occurring in mixtures of unrelated species is of relevance in life sciences and in pharmaceutical analysis. While this is conceptually achievable by comprehensive two-dimensional liquid chromatography (LC × LC), few approaches exist whereby the second dimension comprises the chiral separation. The latter is preferable in combination with a conventional reversed phase type of separation in the first dimension as it offers an extension of a conventional achiral analysis. The implementation of such rapid chiral analyses in the second dimension was, thus far, limited by the challenging transfer of the first dimension mobile phase to the second dimension while still achieving chiral separation. In this study, the combination of temperature-responsive and reversed-phase chiral liquid chromatography is assessed in terms of enantioselective separation of a broad range of pharmaceutical compounds. Applying temperature-responsive liquid chromatography (TRLC) in the first dimension allows for analyses to be performed under purely aqueous conditions, which then allows for complete and more generic refocusing of (organic) solutes prior to the second dimension. This offers an enhanced ability to employ fast and broad compositional gradients over the chiral dimension, which broadens the applicability of the technique. In the proposed platform, seven chiral columns (superficially porous and fully porous columns (comprising both polysaccharide and macrocyclic antibiotic phases)) and four mobile phase gradients were screened on a pharmaceutical test mixture. The platform was shown to be able to offer the necessary resolving power for the molecules at hand and offers a new approach for chiral screening of mixtures of unrelated compounds.

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Comprehensive profiling of conjugated fatty acid isomers and their lipid oxidation products by two-dimensional chiral RP×RP liquid chromatography hyphenated to UV- and SWATH-MS-detection

Cited by 16 publications

References 50 publications

Effect of (De-)protonation on the UV Spectra of Sodium Oleate: Experimental and Electronic Structure Investigation

Effect of (De-)protonation on the UV Spectra of Sodium Oleate: Experimental and Electronic Structure Investigation

Investigating the Potential of Drift Tube Ion Mobility for the Analysis of Oxidized Lipids

Temperature Responsive × Fast Chiral Comprehensive Liquid Chromatography: a New 2D-LC Platform for Resolving Mixtures of Chiral Isomers

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