Retention pattern profiling of fungal metabolites on mixed-mode reversed-phase/weak anion exchange stationary phases in comparison to reversed-phase and weak anion exchange separation materials by liquid chromatography–electrospray ionisation-tandem mass spectrometry

Apfelthaler, E.; Bicker, Wolfgang; Lämmerhofer, Michael; Sulyok, Michael; Krska, Rudolf; Lindner, Wolfgang; Schuhmacher, Rainer

doi:10.1016/j.chroma.2007.12.067

Cited by 86 publications

(43 citation statements)

References 13 publications

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“…However, in comparison to our recently developed mixed-mode separation materials of RP/weak anion exchange type [13], which can inter alia separate compounds by exploiting simultaneously anion exchange and HILIC [14,15], one can usually not make use of RP and HILIC interactions at the same time. Nevertheless, due to the different phase polarities and interactive sites we expected unique selectivity properties to arise on the investigated separation materials both in the HILIC and RP mode.…”

Section: Resultsmentioning

confidence: 99%

Separation properties of novel and commercial polar stationary phases in hydrophilic interaction and reversed‐phase liquid chromatography mode

Bicker

Lindner³

2008

J of Separation Science

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Four novel nonionic polar stationary phases were synthesised by anchoring first 2-mercaptoethanol and 1-thioglycerol, respectively, onto vinylised silica (ME and TG packings) followed by an on-phase oxidation with excess hydrogen peroxide in aqueous medium which yielded sulphoxide analogues of the embedded sulphide groups, i. e. oxidised 2-mercaptoethanol (MEO) and oxidised 1-thioglycerol (TGO) packings. Chromatographic characteristics of these stationary phases were evaluated comparatively to three commercial so-called 'diol' columns. U-shaped response curves of retention factors of adenosine and guanosine with hydro-organic eluents containing 5-95% v/v ACN as well as noticeable CH(2)-increment selectivity demonstrated multimodal separation capabilities of the developed amphiphilic materials, i. e. columns can be operated both in hydrophilic interaction chromatography (HILIC) and in RP mode. Although the selector ligands were physico-chemically related, considerably differing retention and selectivity patterns were observed in the HILIC mode. Thereby the introduction of additional hydroxyl groups in the chromatographic ligand resulted in selectivity increments that were different from those obtained by sulphur oxidation. For example, a set of five vitamins delivered five different elution orders with the overall seven columns. A close examination of HILIC separations of nucleobases and nucleosides on the developed packings revealed that (i) the amount of ACN in the eluent adopts a pivotal role in adjusting retention, (ii) the linearity of the relationship log (retention factor) versus log (volume fraction of water in the eluent) increases with phase polarity in the range of 5-40% v/v water, (iii) the slopes are higher with solutes having more polar interactive sites, (iv) the van't Hoff plots are linear (range 15-45 degrees C) with negative retention enthalpy values DeltaH (-4.5 to -14.5 kJ/mol) and (v) the -DeltaH values tend to be higher with more polar phases and more polar analytes. Based on these data the HILIC retention mechanism is described to be composed of both partitioning and adsorption processes. Distinct types of polar interactive sites in the chromatographic ligands may generate mixed-mode HILIC separation conditions that may additionally be superimposed by surface silanol contributions.

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Section: Resultsmentioning

confidence: 99%

Separation properties of novel and commercial polar stationary phases in hydrophilic interaction and reversed‐phase liquid chromatography mode

Bicker

Lindner³

2008

J of Separation Science

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“…5). In contrast, the position of the acidic solutes relative to the neutral compounds in the chromatogram can be easily varied or adjusted by either a change of the total ion-exchange capacity of the stationary phase through alteration of the ligand coverage or by a change of the actual ion-exchange capacity through variations of the ionic strength or the pH of the eluent [22]. With a slight reduction of the anion-exchange capacity of the mixed-mode phase from 0.36 to 0.24 mmol/g the retentivity of the RP/WAX-AQ phase for the acidic constituents in the test mix was diminished, while both the hydrophobic selectivity between the alkylbenzenes and the acid selectivity between hydrophilic DETP and more lipophilic Boc-Pro-Phe were still more or less maintained (cf.…”

Section: Comparison Of Various Mixed-mode Rp/wax Phasesmentioning

confidence: 99%

“…Some of the mixed-mode phases of Fig. 1 have been proposed recently in various applications [10, 11, 20 -23] such as peptide separations [10], organophosphate metabolism studies [20], ethanol consumption marker analysis in urine [21], and chromatographic profiling with mycotoxins [22]. It is the goal of the present study, to further illustrate the chromatographic characteristics of these mixed-mode RP/weak anion-exchangers (RP/WAX) stationary phases by simple chromatographic tests providing information on their hydrophobic selectivity and ion-exchange capacity using an RP-type elution mode (40% ACN in buffer).…”

Section: Introductionmentioning

confidence: 99%

Mixed‐mode ion‐exchangers and their comparative chromatographic characterization in reversed‐phase and hydrophilic interaction chromatography elution modes

Lämmerhofer¹,

Richter

et al. 2008

J of Separation Science

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148

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A set of particulate silica-supported mixed-mode RP/weak anion-exchangers (RP/WAX) (obtained by bonding of N-undecenoylated 3-aminoquinuclidine, 3-aminotropane and 2-dimethylaminoethylamine as well as of N-butenoyl-(2S,4S,5R)-2-aminomethyl-5-[(2-octylthio)ethyl]-quinuclidine to thiol-modified silica) were chromatographically characterized in comparison to selected commercially available columns using two distinct isocratic elution modes, viz. an aqueous-rich RP-type elution mode (with 40% ACN and 60% buffer) as well as an organic solvent-rich hydrophilic interaction chromatography (HILIC)-type elution mode (95 and 90% ACN). The mixed-mode RP/WAX phases showed multimodal applicability, unlike a polar embedded RP material (Synergi Fusion RP), amino phases (Luna NH(2), BioBasic AX) or typical HILIC packings (ZIC-HILIC, TSKGel Amide-80). Principal component analysis (PCA) of the RP test data confirmed that the in-house developed RP/WAX columns as well as the Acclaim Mixed-Mode WAX-1 phase resemble each other in their chromatographic characteristics having slightly lower hydrophobic selectivity (alpha(CH2) of 1.5) than the tested Synergi Fusion RP (alpha(CH2) approximately 1.8). In contrast, a decrease in mixed-mode character due to lowered ion-exchange capacity and concomitantly increased RP-like behavior could be identified for other mixed-mode phases in the order of Obelisc R > Primesep B2 > Uptisphere MM3. PCA on HILIC data revealed that the RP/WAX phases behave dissimilar to TSKGel Amide-80, ZIC-HILIC and polysulfoethyl A under the chosen elution conditions. Hence, they may be regarded as complementary to these commercial stationary phases with applicability profiles for hydrophilic but also hydrophobic solutes.

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“…Consequently, these columns are not only complementary to reversed-phase columns but also provide different selectivities under different conditions. [22][23][24][25] The presence of both reversed-phase and ion-exchange functionalities requires no ion-pairing agent in the mobile phase to separate highly hydrophilic charged analytes, thus simplifying the mobile phase and making the method compatible with MS. 20,21 Previous reports suggest that mixed-mode columns capable of both reversed-phase and ion-exchange separation modes can be of some value for improved separation of polar substances. 26,27 Actually, these columns with gradient mode showed significant improvements in the peak shape of oligonucleotides.…”

Section: Lc-ms/ms Analysis Of L-carnitinementioning

confidence: 99%

Quantitative Determination of Total L-Carnitine in Infant Formula, Follow-up Formula, and Raw Materials by Liquid Chromatography with Tandem Mass Spectrometry

et al. 2014

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Retention pattern profiling of fungal metabolites on mixed-mode reversed-phase/weak anion exchange stationary phases in comparison to reversed-phase and weak anion exchange separation materials by liquid chromatography–electrospray ionisation-tandem mass spectrometry

Cited by 86 publications

References 13 publications

Separation properties of novel and commercial polar stationary phases in hydrophilic interaction and reversed‐phase liquid chromatography mode

Separation properties of novel and commercial polar stationary phases in hydrophilic interaction and reversed‐phase liquid chromatography mode

Mixed‐mode ion‐exchangers and their comparative chromatographic characterization in reversed‐phase and hydrophilic interaction chromatography elution modes

Quantitative Determination of Total L-Carnitine in Infant Formula, Follow-up Formula, and Raw Materials by Liquid Chromatography with Tandem Mass Spectrometry

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