HPLC End-Capped Column

 

HPLC End-Capped Column

¨  End-capped column are those in which the residual silanol group in a bonded stationary phase are replaced with the trimethysilane (TMS).

¨  During the functionalization of silica gel the reactivity upon all the available silanol groups is impossible and therefore some of the silanol groups remains freely available.

¨  It is needed to reduce the available silanol groups  with a second grafting with a small hydrophobic group like TMS.

¨  With the application of end-capping the free silanol groups in the bonded stationary phase are not more easily available to react thus the silanol group activity is reduced and its dissolution due to reaction is decreased.

Stationary Phase Bonding and TMS Reaction

¨  Hexamethyldichlorotrisiloxane can also be used in end-capping of the column.

¨  In this technique 1^st Hexamethyldichlorotrisiloxane is used as end-capping after that TMS is applied as 2^nd end-capping thus a two step end-capping occurred.

¨  Beside using end-capping reagent end-capping can by done by converting silanol group to siloxane by heating.

Application

¨  End-capped columns are more stable at both acidic and basic conditions and that’s why are more valuable in pharmaceutical industry.

¨  End-capped columns are more efficient for analyzing basic compounds.

¨  End-capped columns are more effective for mid pH range analysis.

 Ratting Spot

Presented By

Muhammad Atif

PhD Scholar Pharmaceutical Sciences AWKUM

Manager QA Decent Pharma Islamabad