Direct Determination Of Enantiomeric Purity Research Articles

Development and validation of a supercritical fluid chromatography method for the direct determination of enantiomeric purity of provitamin B5 in cosmetic formulations with mass spectrometric detection

A rapid and efficient chiral supercritical fluid chromatography (SFC) method has been developed for the quantitative determination of panthenol enantiomers in cosmetic formulations (cream, lotion, wipe, and exfoliant). Indeed, the pharmacological effect only depends on the D form (Dexpanthenol) thus accurate measurement of its enantiomeric purity in formulated cosmetic products is of interest. The samples were prepared with liquid–liquid extraction followed by solid-phase extraction on Adsorbex amino cartridges. After testing several enantioselective columns in an attempt at reversing the elution order to have the minor enantiomer eluted first, the best separation of enantiomers and internal standard (N-acetyl-l-alanine) was achieved on a 3μm-amylose-type immobilized polysaccharide chiral stationary phase (Chiralpak IA) in less than 6min with a simple mobile phase comprising carbon dioxide and 11% methanol pumped at 2.3mL/min, 25°C and 150bar backpressure. Supercritical fluid chromatography coupled to both an optical diode-array detector and a user-friendly single-quadrupole mass spectrometer (Waters QDa) equipped with electrospray ionization source has been used. The on-line coupling ensures the technique to be more informative and improves detection sensitivity, as underivatized panthenol has a poor UV absorption. The limit of quantification (LOQ) achieved with single-ion recording was 0.5μg/mL. The method was validated in terms of linearity, precision and accuracy and satisfactory results were obtained.

ChemInform Abstract: First Principles Design of Derivatizing Agent for Direct Determination of Enantiomeric Purity of Chiral Alcohols and Amines by NMR Spectroscopy.

AbstractA novel Se‐based chiral derivatizing agent (IV) for the determination of the enantiomeric purity of alcohols and amines using NMR spectroscopy is described.

First principles design of derivatizing agent for direct determination of enantiomeric purity of chiral alcohols and amines by NMR spectroscopy

(77)Se NMR offers superior sensing of chirality within the structure of the diastereomers (Deltadelta up to 6.1 ppm), compared to (13)C (Deltadelta < 1 ppm) and (1)H (Deltadelta < 0.2 ppm). The developed procedure is equally well suitable for determination of the enantiomeric purity of chiral alcohols and amines as pure samples as well as reaction mixtures and crude products.

ChemInform Abstract: Chiral t‐Butylphenylphosphinothioic Acid: A Useful Chiral Solvating Agent for Direct Determination of Enantiomeric Purity of Alcohols, Thiols, Amines, Diols, Amino Alcohols and Related Compounds.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Chiral separations of β-blocking drug substances using the Pirkle-type α-Burke 1 chiral stationary phase

The Pirkle-type α-Burke 1 chiral stationary phase (CSP) column has been evaluated for the enantiomeric separation of β-blocking drug substances and suitability for the determination of enantiomeric purity of these substances. Eighteen β-blockers currently on sale in Denmark were investigated. By varying the amount of alcohol modifier in the mobile phase, a total of fifteen of the eighteen investigated β-blockers were successfully separated by straight-phase HPLC within acceptable analysis times (i.e. below 20 min). The separation factors ranged between 1.07 and 1.41, and the resolutions were in no case less than 0.9. The possible use of the column for a direct determination of enantiomeric purity of the drug substances was also investigated. Validation studies, in which the enantiomers of propranolol were used, were performed in accordance with the ICH guideline, Validation of Analytical Procedures. The limit of detection for R-propranolol in S-propranolol was estimated to be ca. 0.1% and the limit of quantification ca. 0.3%.

Chiral t-butylphenylphosphinothioic acid: A useful chiral solvating agent for direct determination of enantiomeric purity of alcohols, thiols, amines, diols, aminoalcohols and related compounds

Enantiomers of t-butylphenylphosphinothioic acid were found to be useful chiral solvating agents (CSAs) for 1H-NMR determination of enantiomeric excess (ee) of many classes of chiral organic compounds, such as alcohols, diols, thiols, mercaptoalcohols, amines, aminoalcohols, hydroxyacids and related compounds.

Direct determination of enantiomeric purity of FMOC amino acids with high performance liquid chromatography

Analytical methods are described which allow a direct determination of enantiomeric purity of seventeen FMOC amino acids commonly used in peptide synthesis. The corresponding ester derivatives can be separated directly on cellulose tris(3,5-dimethylphenylcarbamate) (Chiralcel-OD). The methods are suitable for primary as well as secondary FMOC amino acids. The presence of a highly sensitive fluorescence moiety within the molecule, in combination with large separation factors (α-values between 1.5–2.2) allowed for a general detection limit below 0.05%. In several cases the antipode has been determined in the ppm-range. An interesting result has been observed with respect to the elution order of the FMOC amino acid esters. The elution order of the Trp enantiomers is opposite to that obtained with the other amino acids. This is contrary to the generally held belief that elution order is identical within a homologous series of racemates when chromatographed under identical conditions on the same chiral stationary phase. In addition, the inversion of elution of the Pro enantiomers depending on the estertype indicates a competition of different separation mechanisms.