Universal Polar Embedded Alkylamide

Exmere’s first polar embedded phase, the Avanti Quattro, gives excellent performance for all compounds at low pH and exceptional performance  for bases at neutral pH. To compliment its performance envelope,  we have produced an alkylamide phase based on our Avanti BDS.

The Alkam phase utilises our highly purified, base deactivated, 145Å Avanti BDS which is carefully bonded with a stable alkyl amide phase of medium chainlength using decanoic acid. This results in a phase which shows reduced base retention compared with an alkyl bonded phase on the same silica. Peak shape for bases is also improved over the alkyl phase while the problem of tailing with acids which is sometimes encountered with amide phases, is overcome by the careful bonding procedure.

The attached selection of chromatograms shows the excellent peak shape of acids, bases and chelates at low pH and the maintenance of good peak shape for bases at neutral pH.

Phase stability appears good and it is even capable of being operated at pH 12 for short periods with minimal change as is shown in the attached chromatograms. Longer periods at this pH should be avoided.  The phase resists phase collapse at low organic content and allows its use with 100% aqueous eluents.

Compared with the Avanti Quattro, the retention of bases is higher and there is a difference in selectivity e.g. at pH 7, Nortriptyline elutes before Doxepin on the Quattro but after on the Alkam.

Applications

Stability at pH 12

Acids, Bases and Neutrals at pH 3

Bases at pH 3

Pydridine and Chelates at pH 3

Nucleosides at pH 2

Base at pH 7