Scope of partial least-squares regression applied to the enantiomeric composition determination of ketoprofen from strongly overlapped chromatographic profiles.

Valuable quantitative information could be obtained from strongly overlapped chromatographic profiles of two enantiomers by using proper chemometric methods. Complete separation profiles where the peaks are fully resolved are difficult to achieve in chiral separation methods, and this becomes a particularly severe problem in case that the analyst needs to measure the chiral purity, i.e.

Measurements of association constants between enantiomers and chiral selectors by capillary gas chromatography. Theoretical and practical considerations.

The association constants of several volatile enantiomers with octakis(3-O-butanoyl-2,6-di-O-pentyl)-γ-cyclodextrin at temperatures between 50 and 100 °C were measured by gas-liquid chromatography using capillary columns coated with different amounts of chiral selector dissolved in polysiloxane OV-1701 and prepared with a precisely determined phase ratio. Simple expressions were deduced to estimate the apparent distribution constants from accurate hold-up and retention times along with that known phase ratio at each temperature. The enantiomer-chiral selector association constants were then calculated from the linear regression of the apparent constants as a function of the chiral selector concentration.

Development of a chiral stationary phase based on cinchonidine. Comparison with a quinine-based chiral column.

A chiral anion-exchanger stationary phase based on cinchonidine (CD) was developed. Two columns were packed with and without endcapping (EC) treatment (CD-chiral stationary phase[CD-CSP(EC)] and [CD-CSP], respectively) and studied for their ability to separate N-2,4-dinitrophenyl α-amino acids (DNP-amino acids) enantiomers over a temperature range of 10-40 °C with a hydro-organic buffer mobile phase. The more hydrophobic, endcapped stationary phase showed significantly larger retentive capacity than the non-endcapped one.

Determination of enantiomeric composition of ibuprofen in pharmaceutical formulations by partial least-squares regression of strongly overlapped chromatographic profiles.

In this report, we demonstrate how chiral liquid chromatography combined with multivariate chemometric techniques, specifically unfolded-partial least-squares regression (U-PLS), provides a powerful analytical methodology. Using U-PLS, strongly overlapped enantiomer profiles in a sample could be successfully processed and enantiomeric purity could be accurately determined without requiring baseline enantioresolution between peaks. The samples were partially enantioseparated with a permethyl-β-cyclodextrin chiral column under reversed-phase conditions.

Rapid and sensitive gradient liquid chromatography method for the quantitation of ion from neutrophils.

We developed an improved reversed-phase high-performance liquid chromatography (RPLC) assay for the rapid separation and determination of the 2-hydroxyethidium ion. The 2-hydroxyethidium ion is the specific product of the redox reaction between hydroethidine with superoxide radical. High resolution between the chromatographic bands corresponding to ethidium and 2-hydroxyethidium ions was achieved within a practicable analysis time.

Fast RPLC analysis of pharmaceutical compounds at intermediate temperatures by using a conventional instrument.

Recent developments in HPLC methods have focused on various strategies in order to increase the speed of analysis. One area of impressive growing is column technology. Today, analytical methods that propose the use of short columns packed with sub-2 μm particles installed in ultra high-pressure LC instruments are not uncommon.

Permethylated beta-cyclodextrin in liquid poly(oxyethylene) as a stationary phase for capillary gas chromatography.

This paper reports the study of poly(oxyethylene) as a solvent for heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin (PM-beta-CD) and the potential of these mixtures for constructing enantioselective gas chromatography columns. Enantioseparations of volatile racemic mixtures using capillaries coated with 10-50% PM-beta-CD diluted in Carbowax 20M were evaluated. The influence of the polymer type on retention, separation and reproducibility over a period of time is critically discussed.