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

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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