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.

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.

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.

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.

Extracting pure fullerene (C60) from fullerene soot was accomplished in two steps. In the first step, extraction was carried out using a Soxhlet extractor. Different solvents, such as toluene, were used in this method. In this process, light and heavy fullerenes were separated from impurities such as soot and other compounds. The applied fullerene soot was produced using an electric arc method, and the obtained purity was close to 7%. In the next step, fullerene C60 can be separated from other fullerenes (particularly C70) by column chromatography. The STATIONARY phase in the chromatography column contained a mixture of activated carbon, silica gel, and celite, and in order to achieve a high efficiency for separation, the column was filled with a combination of these compounds. Organic solvents such as chlorobenzene and 1, 2-dichlorobenzene were used as the mobile phase. Several experiments were designed and conducted to obtain optimal conditions, and consequently, the fullerene C60 was purified with proper efficiency. In this method, parameters including efficiency, low cost, and simplicity are of great importance in the aim of obtaining an optimized method. As a result, a suitable method with low cost and high efficiency was used in this research.