Covalently Bonded CSPs
Sumichiral OA columns utilise covalently bonded stationary phases (CSPs). This means that the columns are very stable, long lived and exhibit excellent column-to-column and batch-to-batch reproducibility. Covalent bonding means that eluents or sample solutions containing water do not adversely affect or permanently change column selectivity.

Twenty-one Different Phases
Sumichiral OA columns are generally classified according to the type of linkage used to attach the asymmetric carbon. Amide types exhibit good separation of aromatic compounds, esters, carboxylic acids and alcohols. Urea types provide a higher level of hydrogen bonding for pharmaceutical amines, amino alcohols, esters and amides. The ligand exchange phases offer chiral discrimination in reversed phase mode. They are effective for the direct enantiomer separation of amino acids, hydroxy acids and as copper chelate-forming compounds with aminoalcohols, diamines, etc.

Type of Linkage

• Amide Type: Asymmetric carbon atoms are bonded directly with CONH group
  (OA-2000 series).
• Urea Type: Asymmetric carbon atoms are bonded directly with NHCONH group (OA-3000, 4000 series).
• Ligand exchange type: The chiral components are coated hydrophobically on ODS
  (OA-5000, 6000 series).
• Host-Guest type: Cyclodextrin bonded chiral stationary phase with novel spacer
  (OA-7000 series). Novel chiral Stationary phase bonded with crown ether (OA-8000 series).

OA-2000 series have a 3,5-dinitrobenzoyl group as the p-acid and can interact with the solute molecule by charge transfer, hydrogen bonding, etc. The enantiomers of aromatic compounds, esters, carboxylic acids and alcohols may be directly separated on OA-2000 series. OA-2000 is especially useful for pyrethroidal esters, OA-2500 for carboxylic acids such as profens, and OA-2500-I for aromatic alcohols and esters of hydroxy carboxylic acids.

OA-3000 series have a 3,5-dinitrophenylurea group as the p-acid and, in the reversed phase mode, allow the chiral separation by charge transfer, hydrogen bonding, etc. In general OA-3000 series are useful for carboxylic acids, and especially for acetyl- and urethane-amino acids, dansylamino acids. OA-3300 offers good direct separation for profens, acetyl-amino acids, BOC-amino acids and benzoyl-amino acids.

OA-4000 series have a naphthyl group as the p-base, and two chiral centres at amine and amino acid group. Chiral separations can be perfomed via charge transfer, hydrogen bonding, etc., interactions and a wide variety of compounds such as pharmaceuticals containing amine and amino alcohol, alcohols, esters and amides can be directly resolved in the normal phase mode. Amide and urethane derivatives of amines, alcohols, etc. can also be resolved effectively.

OA-5000 and 6000 series offer chiral separations by ligand exchange interaction in the reversed phase mode, although the volume of organic solvents which can added to the mobile phase is limited. They are effective for direct enantiomer separation of not only amino acids, hydroxy acids but also copper chelate-forming compounds such as amino alcohols, diamines, dicarboxylic acids, aminolactames and dipeptides. OA-5000 can be applied to an extremely wide range of compounds.

OA-7000 series are stationary phases bonded with β-cyclodextrin derivatives to the silica gel via new type of spacer. A large number of racemates, including amines, ketones and amino acid derivatives can be separated under reversed phase conditions. OA-7000 is typically operated under reversed phase conditions using the mixtures of phosphate buffer (pH 2-3.5) and methanol or acetonitrile, and special solvents are usually not required. The major merits of this column are sharp peaks, high theoretical plate number and exceptional resolution for a wide variety of important chiral compounds.

OA-8000 series are novel chiral stationary phases bonded with chiral crown ether to aminopropyl silica gel. This is very effective for enantiomer separation of minies, aminoalcohols and amino acids, especially for hydrophobic amines. OA-8000 is covalently bonded and can be used in reversed phase and normal phase mode. Sharp peaks and high theoretical plate numbers are obtained.