Separation of aromatic aminophosphonic acid enantiomers by capillary electrophoresis with the application of cyclodextrins

Rudzińska, Ewa; Dżygiel, Paweł; Wieczorek, Piotr; Kafarski, Paweł

doi:10.1016/s0021-9673(02)01248-7

Cited by 25 publications

(14 citation statements)

References 19 publications

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“…Phaclofen (2) behaves like a diacid/ monobase having pK a of 1.93, 7.03 and 10.71. Some aanalogs of phaclofen have pK a values of around 0.60, 5.73, and 9.16 [33,34]. The homologation of the aliphatic chain induces a decrease of the acidic strength.…”

Section: Calculation Of Pk a Valuesmentioning

confidence: 99%

Enantiomeric analysis of baclofen analogs by capillary zone electrophoresis, using highly sulfated cyclodextrins: Inclusion ionization constant pKa determination

et al. 2005

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Using cyclodextrin-capillary zone electrophoresis (CD-CZE), baseline separation of baclofen phaclofen, saclofen, and hydroxy-saclofen, potent gamma-aminobutyric acid(B) (GABA(B)) agonist or antagonists was achieved. A method for the enantioresolution of those analogs of GABA was developed using anionic cyclodextrins (highly sulfated CD or highly S-CD) as chiral selectors and capillaries dynamically coated with polyethylene oxide (PEO). With charged CDs we observed good resolutions due to the large electrophoretic mobility of these chiral selectors opposite to the mobility of the solutes. The highly S-alpha-CD and S-beta-CD were found to be complementary and the most effective complexing agent, allowing good enantiomeric resolution in short runtimes. The complete resolution was obtained using 25 mM phosphate buffer at pH 2.5 containing 3% w/v of highly S-alpha-CD or S-beta-CD at 25 degrees C with an applied field of 0.30 kV/cm. The apparent binding constants of the inclusion complexes were evaluated and the migration order was determined. A comparison was possible to investigate the importance of the anionic group of the molecules in the separations. The pK(a) values were determined for all four compounds in order to explain relative electrophoretic migration of the solutes.

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Section: Calculation Of Pk a Valuesmentioning

confidence: 99%

Enantiomeric analysis of baclofen analogs by capillary zone electrophoresis, using highly sulfated cyclodextrins: Inclusion ionization constant pKa determination

et al. 2005

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“…Yet, studies on stereoselective separations of chiral phosphinate analogues of amino acids and peptides have rarely been reported. For instance, CZE employing CDs as chiral additives to the BGE has been used for the enantioseparation of aminophosphonic and phosphinic acid peptide analogues [3][4][5]. Also HPLC separations have been described utilizing chiral cellulose or amylose phases [5] or anion-exchange-type cinchona alkaloid-derived chiral stationary phases (CSPs) [6].…”

Section: Introductionmentioning

confidence: 99%

Stereoselective separations of chiral phosphinic acid pseudodipeptides by CEC using silica monoliths modified with an anion‐exchange‐type chiral selector

et al. 2006

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A nonaqueous CEC method for the simultaneous separation of the four stereoisomers of the N-benzyloxycarbonyl phosphinic pseudodipeptide methyl ester benzyloxycarbonyl-homophenylalanine Z-hPhepsi(PO2HCH2)Phe-OCH3 as well as of the corresponding N-2,4-dinitrophenyl (DNP)-derivative with free C-terminal carboxylic group DNP-hPhepsi(PO2HCH2)Phe-OH was developed. For this purpose, a monolithic silica capillary column modified with a cinchona alkaloid-derived anion-exchange-type chiral selector, namely O-9-(tert-butylcarbamoyl)quinidine (tBuCQD) was prepared. The mobile phase composition (ACN/methanol ratio, counterion type) was thoroughly optimized to end up with baseline resolution of all four stereoisomers with critical resolution of as high as about 2. The CEC method proved to be superior over the corresponding HPLC separations primarily due to significantly enhanced plate numbers (between 200,000 and 600,000 m(-1) in CEC). Diastereoselectivity contributions arising from electrophoretic mobility differences of the diastereomers facilitated the separation of the later eluted diastereomeric peak pair (peaks III and IV), but had a negative influence on the selectivity of the earlier eluted diastereomeric peak pair (peaks I and II). The stereoselective CEC assay allowed the assessment of the stereoisomeric purity of the individual isomers which were obtained by preparative HPLC on a CHIRALPAK QD-AX column that is based on the same tBuCQD selector. The present study demonstrates that there exist problems which are hard to solve by HPLC, yet can be conveniently solved by CEC. Moreover, it was intended to prove by this practical application that CEC with monolithic columns is robust enough to be used for solving real-life problems.

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“…1) used in this study are small molecules with one (compounds 1-11) or two (compounds 12-14) chiral centers and pK a values around 1.5 and 6.0 for the phosphonic acid group and 10.0 for the amino group. Amino acids form diastereomeric inclusion complexes with CDs and this phenomenon has been used for the separation of their enantiomers by various techniques [14,16,22,23]. Continuing our work on the separation of enantiomers of these acids by CE we have now studied the suitability of this method for determination of optical purity of UV nonabsorbing species, i.e., those containing aliphatic side-chains.…”

Section: Resultsmentioning

confidence: 99%

“…Capillary electrophoresis with UV detection seems to be a promising method, here although, it has been used only in a limited number of cases and only for compounds containing aromatic rings in the molecule [7,[12][13][14][15]. In our previous reports [14,16] we have studied the application of capillary zone electrophoresis with commercially available cyclodextrins used as chiral selectors for the separation of aromatic aminophosphonates. The principle aim of this work was to evaluate the applicability of capillary zone electrophoresis for fast and simple determination of the optical purity of UV nonabsorbing aminophosphonates.…”

Section: Introductionmentioning

confidence: 99%

Separation of aminoalkanephosphonic acid enantiomers by indirect UV detection capillary electrophoresis with application of cyclodextrins

Rudzińska¹,

Wieczorek²,

Kafarski³

2003

Electrophoresis

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Indirect UV detection capillary electrophoresis (CE) was used for the separation of aminoalkanephosphonic acid (AP) enantiomers by applying commercially available cyclodextrins as chiral discriminators. The results show that the separation of the enantiomers depends on pH of the background electrolyte, the molar ratio of cyclodextrin to aminophosphonic acid, and on the type of the applied chiral selector. Optimization of process conditions allowed enantiomeric baseline separation or partial separation of 12 out of 14 alpha-aminophosphonic acids studied. This type of CE might therefore be successfully used for routine determination of enantiomeric purity of aminophosphonic acids.

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Separation of aromatic aminophosphonic acid enantiomers by capillary electrophoresis with the application of cyclodextrins

Cited by 25 publications

References 19 publications

Enantiomeric analysis of baclofen analogs by capillary zone electrophoresis, using highly sulfated cyclodextrins: Inclusion ionization constant pKa determination

Enantiomeric analysis of baclofen analogs by capillary zone electrophoresis, using highly sulfated cyclodextrins: Inclusion ionization constant pKa determination

Stereoselective separations of chiral phosphinic acid pseudodipeptides by CEC using silica monoliths modified with an anion‐exchange‐type chiral selector

Separation of aminoalkanephosphonic acid enantiomers by indirect UV detection capillary electrophoresis with application of cyclodextrins

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