Pirkle Type Chiral Columns

The purposes of using pre-column derivatization are:

• Blocking of the polar groups of the analyte (amino, carboxyl, hydroxyl groups) to avoid strong interactions with the polar groups of the chiral selector thus improving the separation.

• The introduction of aromatic rings into the analyte to enable n-n interactions to take place between the aromatic moieties of the chiral selector and the analyte which play a dominant role in the resolution of the enantiomers.

• Improve UV detectability.

To fulfil these requirements amino groups in the analyte are usually transformed to aromatic acyl derivatives by 4-nitro- or 3,5-dinitrobenzoyl chloride or to aromatic urea or thiourea derivatives by means of phenyl-, 4-fluorophenyl-, 4-methoxyphenyl-, 3,5-dinitrophenyl- or 1-naphthyl-isocyanates and iso-thiocyanates. Carboxyl derivatives are derivatized after activation with thionyl chloride or carbodiim-ides to form anilides, 3,5-dimethylanilides, 3,5-dinit-roanilides, naphthylmethylamides, etc. The derivatiz-ing agents for the hydroxyl group are benzoyl chloride, 3,5-dinitrobenzoyl chloride, 1-naphthyl chloride to form ester derivatives and 1-naphthyl- or 3,5-dinit-rophenyl isocyanates to form the corresponding car-bamates.

Solar Panel Basics

Solar Panel Basics

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