The high performance liquid chromatography (HPLC) enantioseparation of four b-blocking agents metoprolol, bisoprolol, propranolol and atenolol was performed on amylose tris- (3, 5- dimethylphenylcarbamate) CHIRAL STATIONARY PHASE using n-hexane-ethanol-diethylamine (DEA) as the mobile PHASE and related CHIRAL recognition mechanisms were discussed. Enantiomeric separation of the four b-blockers was a result of more than one type of interaction between solutes and CSP. Besides hydrogen bonding, there was another type interaction that was independent of solvent polarity and responsible for enantiomeric selectivity, such as p-p interactions. Both the groups close to the CHIRAL centers and the substituent groups on the phenyl rings, which were far away from the CHIRAL centers, could contribute to the good separation. The separations of the four b-blocker enantiomers were all enthalpy driven process. In the range of 293–308K (20–35 oC), as the temperature increased, the retention as well as the resolution decreased. The molecular size rather than concentration of the alcohol modifiers affected the resolution and retention.

A rapid, sensitive and reproducible HPLC method has been developed for enantioseparation of six non-steroidal anti-inflammatory drugs, which are acidic compounds: carprofen, fenoprofen, flurbiprofen, ibuprofen, indoprofen and ketoprofen. The effects of the mobile PHASE composition on retention times and resolutions of the analytes were studied. A column based on vancomycin immobilized by reductive amination to aldehyde functionalised silica was prepared in house and used. The prepared sorbent shows a great stability and selectivity over a range of pH (4-6), and the separation was carried out using the mobile PHASE composed of a mixture of 40 % of methanol in ammonium nitrate buffer (50 mM) at pH 5.0. Another mobile PHASE consisted of 50 % of methanol in phosphate buffer (5 mM) at pH 5.0 was also prepared and tested. The two mobile PHASEs are the optimum conditions obtained. All experiments were conducted at flow rate 0.6 ml/min, using a UV detector wavelength at l=254 nm.

Here we report the synthesis of a novel covalently immobilized calix[4]arne derivative as a CHIRAL STATIONARY PHASE (CSP) for HPLC. In the structure of CSP, the upper rim of calix[4] arne is substituted with two L-alanine units and the lower rim of calix[4]arene is linked to the silica gel by thiol-ene click chemistry. Elemental analysis of the CSP showed 120 μ mol of CHIRAL selector bonded per gram of silica gel. 1-Hexene was used for end-capping of unreacted mercapto groups on silica gel. The CSP is chemically bonded to the silica and can be used in the normal-PHASE mode, reversed-PHASE mode, and with halogenated solvents mobile PHASEs, if desired. The chromatographic performance of the CSP was evaluated with enantioseparation of the 3, 5-dinitrobenzoyl (DNB) derivatives of some amino acids.

In recent years there has been considerable interest in the synthesis and separation of enantiomers of organic compounds especially because of their importance in the biochemistry and pharmaceutical industry. High-performance liquid Chromatography is a very useful method for the direct separation of enantiomers. However, about 30−40 years ago, commercially available CHIRAL STATIONARY PHASEs were very limited. Researchers developed many novel CHIRAL STATIONARY PHASEs for gas and liquid chromatography, and found these PHASEs were effective practically to the separation and analysis of various CHIRAL compounds. Enantioseparation of drugs with multiple CHIRAL centers is challenging. This review describes resolution of some drugs with multiple CHIRAL centers using polysaccharide-type CHIRAL STATIONARY PHASEs.

Experimental determination of solubility and ternary PHASE diagram of CHIRAL compound are of tedious and time consuming tasks, and in many cases, there is not enough experimental data for different enantiomeric compositions to access the experimental ternary PHASE diagram. Using thermodynamic models with predictive capability, having less dependency on experimental data, affords a great advantage for ternary PHASE diagram modeling of these compounds. In this study, NRTL-SAC model, as one of the known and famous predictive models in the solubility modeling of pharmaceutical compounds, has been applied to ternary PHASE diagram modeling of CHIRAL medetomidine salts in alcohols. NRTL-SAC molecular parameters of each CHIRAL compound were calculated just by using racemic point solubility data before being used for the solubility prediction of other enantiomeric compositions. The results of thermodynamic modeling and the predictive data are compared with those of the experimental data. Root mean square error (RMSE) is also calculated for each compound. It was observed that, there is a small deviation between predictive and experimental ternary PHASE diagrams. The eutectic points of CHIRAL compounds in both racemic and conglomerate forms are also well predicted through this method.