Page 187 - Modern Derivatization Methods for Separation Sciences

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2.4—
Label of Hydroxyl-OH

There are many bioactive molecules containing hydroxyl groups. Alcohols, carbohydrates and lipids are
very important compounds in life systems, and many pharmaceuticals have hydroxyl groups. However,
a large number of these compounds do not have the UV absorbing groups of fluorophores, they must be
derivatized with suitable reagents for sensitive ultraviolet-visible detection. In addition to this the
hydrophilic property of hydroxyl groups is a major disadvantage for chromatographic separation. For
the derivatization of hydroxyl groups, acyi halides, acid anhydrides, isocyanates and other compounds
having a light absorbing group are often used.

2.4.1—
Acyl Halides

Benzoyl chloride is widely used for derivatizing reagents for ultraviolet detection. It reacts with the
hydroxyl group in alkaline conditions to form esters and the derivatives are detectable at about 230 nm.
The reaction is shown in Fig. 2.28. Vollmer et al. [112] reported the rapid analytical method of ethylene
glycol and propylene glycol in human serum using RP-HPLC. The method is free from interference by
other common volatile

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