Numerical and experimental investigation of analyte breakthrough from sampling loops used for multi-dimensional liquid chromatography

Moussa, Ali Ben; Lauer, Thomas; Stoll, Dwight R.; Desmet, Gert; Broeckhoven, Ken

doi:10.1016/j.chroma.2020.461283

Cited by 13 publications

(10 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…dictated the experimental conditions used, which were not necessarily optimal for the 1 mm columns. For example, the system external volume was the same for all column combinations, and relatively large loop volumes were used to accommodate relatively high 1 D flow rates without sample loss due to loop overload . We expect that significant improvements can be obtained for the 2.1 mm × 1 mm TRLC × RPLC configuration by minimizing extra-column volume and system dwell volumes.…”

Section: Resultsmentioning

confidence: 99%

“…34 The sum of these area fractions reconstructs the 1 D peak and the total amount of compound injected, 33 if no loss due to sampling by overfilling of the loops occurs. 35 This method was thus chosen for the work here. Quantitative work in LC × LC is still limited and especially LOD evaluations, potentially due to the high time requirements for data evaluation and nonstandardized data treatment.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…For example, the system external volume was the same for all column combinations, and relatively large loop volumes were used to accommodate relatively high 1 D flow rates without sample loss due to loop overload. 35 We expect that significant improvements can be obtained for the 2.1 mm × 1 mm TRLC × RPLC configuration by minimizing extracolumn volume and system dwell volumes. Also, more 1 mm columns should be compared in terms of efficiency, permeability, and sample loading capacity.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

See 2 more Smart Citations

Enhanced Sensitivity in Comprehensive Liquid Chromatography: Overcoming the Dilution Problem in LC × LC via Temperature-Responsive Liquid Chromatography

et al. 2022

Self Cite

View full text Add to dashboard Cite

In comprehensive two-dimensional liquid chromatography (LC × LC), solvents of high eluotropic strength are frequently used in the first dimension ( 1 D), which lead to peak broadening in the second dimension ( 2 D). In the majority of the current LC × LC column combinations, analytes are less than optimally refocused upon transfer to the second column, which negatively affects sensitivity. Furthermore, the typical combination of 1 or 2.1 mm columns in the 1 D paired with a 3 mm (or broader) column in the 2 D leads to at least a 9-or 4-fold dilution and a corresponding loss of sensitivity when using concentration-sensitive detectors. This occurs due to the enhanced radial dilution of the analytes in a broader column, while the sensitivity problem is further exacerbated in LC × LC due to the high flow operated 2 D. In this paper, we introduce a solution to neutralize and inverse this dilution problem through a reconcentrating solution using temperature-responsive liquid chromatography (TRLC) in the 1 D, which is a purely aqueous separation mode. Full solute refocusing at the 2 D column head is thereby obtained when TRLC is combined with reversed-phase liquid chromatography (RPLC). This is shown for the combination of a 2.1 mm I.D. TRLC column with decreasing RPLC column diameters (3−2.1−1 mm) operated at the same linear velocities, hence a resulting decrease in dilution, respectively. Ultraviolet (UV) and electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) detection were used to determine the experimental detection limits. Sensitivity improvements with UV detection were somewhat lower than expected, but represent ∼1.5and 3-fold sensitivity enhancement when using a 1 mm I.D. column compared to 2.1 or 3 mm I.D. columns in the 2 D, respectively. This is attributed to extra-column dispersion and the poorer performance of 1 mm I.D. columns. A major benefit of the use of 1 mm I.D. columns in the 2 D is that it allows split-free coupling of 2 D effluent with ESI-MS (at 450 μL/min), making the coupling robust and simple. When using ESI-MS even better, albeit more variable, sensitivity enhancements were obtained on the narrower columns. The benefits of the methodology are demonstrated for paraben test solutes and for phenolic compounds in a blueberry extract by TRLC × RPLC-UV-ESI-TOF-MS.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

See 1 more Smart Citation

Enhanced Sensitivity in Comprehensive Liquid Chromatography: Overcoming the Dilution Problem in LC × LC via Temperature-Responsive Liquid Chromatography

et al. 2022

Self Cite

View full text Add to dashboard Cite

show abstract

“…It was advised, to fill loops to not more than 50% of the loop volume to avoid analyte loss due to the parabolic flow profile of the mobile phase in narrow loops [1]. An advisable filling volume of 50 -80% dependent on the acceptable level of sample loss was further confirmed via simulations and practical work [50]. Due to the limited coiling of the loop and the relatively high 1 D flow rate, a conservative approach in loop filling volume was chosen.…”

Section: Optimization Of Conditions For the Comprehensive Two-dimensi...mentioning

confidence: 99%

Comprehensive two-dimensional temperature-responsive × reversed phase liquid chromatography for the analysis of wine phenolics

Wicht

Baert

Muller

et al. 2022

Talanta

Self Cite

View full text Add to dashboard Cite

“…For example, most models of RP selectivity that are used to guide column selection (i.e., either to identify columns with similar or dissimilar selectivities) for small molecule separations are built upon selectivity measurements made under isocratic conditions [1][2][3][4][5]. Also, the theories used to make predictions about the effect of injection volume and sample composition on peak shapes (i.e., volume overload and mobile Article Related Abbreviations: NK, Neue-Kuss; SSD, sum of squared differences; DAD, diode array detector; LSS, linear solvent strength; MPRE, mean residual percent error phase/sample solvent mismatch) depend on the availability of isocratic retention data for analytes of interest in solvents corresponding to the sample and mobile phase compositions [6][7][8][9][10]. In contrast, retention models (e.g., Dry-Lab and similar tools) are often built as a part of method development using training data obtained under gradient elution conditions [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Accuracy of retention model parameters obtained from retention data in liquid chromatography

Brau

Pirok

Rutan³

et al. 2022

J of Separation Science

Self Cite

View full text Add to dashboard Cite

In liquid chromatography, it is often very useful to have an accurate model of the retention factor, k, over a wide range of isocratic elution conditions. In principle, the parameters of a retention model can be obtained by fitting either isocratic or gradient retention factor data. However, in spite of many of our own attempts to accurately predict isocratic k values using retention models trained with gradient retention data, this has not worked in our hands. In the present study, we have used synthetic isocratic and gradient retention data for small molecules under reversed-phase liquid chromatography conditions. This allows us to discover challenges associated with predicting isocratic k values without the confounding influences of experimental issues that are difficult to model or eliminate. The results indicate that it is not currently possible to consistently predict isocratic retention factors for small molecules with accuracies better than 10%, even when using synthetic gradient retention data. Two distinct challenges in fitting gradient retention data were identified: 1) a lack of 'uniqueness' in the parameters and 2) an inability to find the global optimum fit in a complex fitting landscape. Working with experimental data where measurement noise is unavoidable will only make the accuracy worse.

show abstract

Numerical and experimental investigation of analyte breakthrough from sampling loops used for multi-dimensional liquid chromatography

Cited by 13 publications

References 42 publications

Enhanced Sensitivity in Comprehensive Liquid Chromatography: Overcoming the Dilution Problem in LC × LC via Temperature-Responsive Liquid Chromatography

Enhanced Sensitivity in Comprehensive Liquid Chromatography: Overcoming the Dilution Problem in LC × LC via Temperature-Responsive Liquid Chromatography

Comprehensive two-dimensional temperature-responsive × reversed phase liquid chromatography for the analysis of wine phenolics

Accuracy of retention model parameters obtained from retention data in liquid chromatography

Contact Info

Product

Resources

About