Selectivity Tuning of Serially Coupled (S,S)Whelk-O 1 and (R,R)Whelk-O 1 Columns in HPLC

Dungelová, J.; Lehotay, J.; Krupčík, J.; Čiẑmárik, J; Welsch, Thomas; Armstrong, Daniel W.

doi:10.1093/chromsci/42.3.135

Cited by 17 publications

(14 citation statements)

References 11 publications

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“…[15,18] Also, it was observed that the system must be completely equilibrated, and the temperature controlled in order to obtain the best results. The possibilities and limitations for variation of selectivity in a column system consisting of a bonded -CN phase column and a column containing PEG crosslinked stationary phase were stated according to experimental observations.…”

Section: Resultsmentioning

confidence: 99%

“…Benická et al 1456 From Eqs. [2,15] Equation 11 can be written in the form: Thus, the overall polarity of two columns coupled in series can be tuned by adjusting the mobile phase flow in the individual columns, since weight factors (x A and x B ), often called relative retentivities (F A and F B ), determine the contributions of the individual column polarities to the overall polarity of the column series.…”

Section: Theoretical Background On the Retention In Two Columns Couplmentioning

confidence: 99%

“…The more recently introduced LabExpert software can plan experiments, collect and evaluate results, and adjust chromatographic conditions in real time, according to predefined decision schemes, until a satisfactory separation is achieved. [15] The performance of this method for adjusting the required selectivity was studied using the separation of enantiomers of alkoxysubstituted esters of phenylcarbamic acid. This is an important milestone in the development of an HPLC method, but in addition to separation there are many other method parameters that also need to be optimized.…”

Section: Introductionmentioning

confidence: 99%

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Selectivity Tuning in an HPLC Multicomponent Separation

Benická

Krupčík

Lehotay

et al. 2005

Journal of Liquid Chromatography & Related Technologies

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The optimisation of the selectivity of two columns coupled in series has been investigated in HPLC. Two columns with different polarities (PEG and CN) were coupled in series via a T connector and the retention of analytes chromatographed on the column system was tuned by varying the individual mobile phase flows in the coupled columns. The flow rate ratio necessary for receiving an optimum selectivity was calculated on the basis of the measured retention factors on the individual columns. The performance of this method has been studied by the separation of a model mixture of 17 analytes with various functionalities.

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Section: Resultsmentioning

confidence: 99%

Section: Theoretical Background On the Retention In Two Columns Couplmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Selectivity Tuning in an HPLC Multicomponent Separation

Benická

Krupčík

Lehotay

et al. 2005

Journal of Liquid Chromatography & Related Technologies

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“…It was attributed to the bulkiness produced by the sulfur atoms in the reagent which resulted in steric hindrance phenomenom leading to reversal in elution order (Chen, 2005). Dungelová et al (2004) reported an interesting work by chromatographing a number of enantiomers of alkoxy substituted esters of phenylcarbamic acid on serially connected Whelk-O 1 columns that displayed reversal enantioselectivities [i.e. (R,R) and (S,S) Whelk-O 1 columns].…”

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confidence: 99%

“…(R,R) and (S,S) Whelk-O 1 columns]. It was found that fine tuning of required selectivities as well as the change in elution order of enantiomers were controlled by careful change in the flow rates of the chosen mobile phase in the individual columns (Dungelová et al, 2004). …”

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Reversal in elution order in liquid chromatography—compilation of experimental observations

Srinivas¹

2008

Biomedical Chromatography

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Reversal in elution order in liquid chromatography-compilation of experimental observationsLetter to the Editor To the editorIn today's polypharmacy situation of medical practice, it has become customary for bioanalytical scientists to handle complex chromatography problems as they relate to the separation and quantification of multiple analytes including chiral substrates in the chosen assays (Srinivas, 2004(Srinivas, , 2006(Srinivas, , 2008Xu et al., 2007;Pedersen-Bjergaard and Rasmussen, 2005). Therefore, the elution order of peaks of interest becomes an important factor from both assay development and validation point of view. While it is understood that chromatographic conditions are critical in controlling the elution order, it is generally accepted that within the chosen and validated conditions, mini-adjustments of conditions should not necessarily change the dynamics of separation and more so the elution pattern of the analytes that are being chromatographically separated. A mini-review on this subject matter of reversal of elution order has been published (Okamoto, 2002). This review captures some salient observations relating chiral separations, providing some hints of mechanistic rationale for several examples (Okamoto, 2002).This note aims to cover some of the recent reports that document changes in elution order owing to certain alterations in the chromatographic conditions being employed for the chromatographic separation of various analytes (amino acids, carboxylic acids, polar and basic compounds, etc.). Yoo et al. (2008) found that the employment of an ionic liquid mobile phase modifier such as 1-butyl-3-methylimidazolium tetrafluoroborate had a profound influence on the elution of the binary mixture of amino acids. The authors noted that it was important to optimize the exact amount of the ionic liquid mobile phase modifier since it affected the selectivity and caused the reversal of the elution order of the binary amino acid mixture (Yoo et al., 2008). Gyllenhaal and Stefansson (2008) have shown that, under standard conditions of chromatography using Chiralpak AD column, the elution order could be easily reversed by replacement of the polar alcohol modifiers. In the documented example, it was shown that the reversal of the elution sequence of profen acid enantiomers was brought about by the switching of isohexane:2-propranol by methanol:ethanol (Gyllenhaal and Stefansson, 2008). The previous work of the authors also had suggested that the replacement of methanol by 2-propranol as the polar alcohol modifier could bring about elution reversals of enantiomeric peaks for compounds such as ibuprofen, ketoprofen and naproxen (Gyllenhaal and Stefansson, 2005). However, for the enantiomers of flurbiprofen no reversal in elution was observed, although selectivity was considerably diminished by the aforementioned changes in the alcohol modifier (Gyllenhaal and Stefansson, 2005). Zhou et al. (2008) have carried out chromatography of a range of pharmaceutical compounds (neutral, basic and acidic) on two p...

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