Properties of some stationary phases

The OH groups in this phase make the product compar able to silica. It is of interest for compounds with which it can form hydrogen bonds and is particularly suitable for tetracyclines, steroids, organic acids and biopolymers (proteins), amongst other 

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NH2 is readily oxidized, so peroxides (in diethyl ether, dioxane or tetrahydrofuran) should be strictly avoided. Ketones and aldehydes react to give Schiff bases. Amino silicas are less stable towards hydrolysis than other bonded phases and it is recommended to use a pre-column (scavenger column) to saturate the mobile phase. 

For reactivation of an amino column that had become exhausted as a result of reaction with actone, see 

The amino group acts as a weak anion exchanger in aqueous acidic solutions (taking the form of primary ammonium ion, RNH ) hence retention in an aqueous mobile phase is a function of pH. 0.1 M ammonia solution can be used to regenerate the RNH2 form. 

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As it has a lower polarity, this phase often gives separations in a similar way to silica, but the k values are smaller for the same mobile phase. It is particularly selective towards components with double bonds and towards tricyclic antidepressants. An application from this latter field is presented in Fig. 11.2. 

Sugar and glycoside analysis (Fig. 11.3) is the classical use for amino phases. The amino function can act as both a proton acceptor and a proton donor in 

For reactivation of an amino column that had become exhausted as a result of reaction with actone, see D. Karlesky, D. C. Shelly and 1. Warner, Anal. Chem., 53, 2146 (1981). 

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