Greater pH Stability(1.5-9.5)/
High Planar Selectivity

Proteins and peptides are often separated using acid buffers; typically trifluoroacetic acid (TFA). Modified silane is often released from the silica packing in this case. This is an important problem which results in shorter life time of the Column and contamination of the sample with C18 functional groups. The nµmber of theoretical plates, N, and capacity factor, K', are also strongly affected when the nature of the silica surface is changed.

In Figure 1, below, test of hydrolysis stability of packing, including Wakosil-II AR, were performed by purging the Columns with 1%TFA in water at 60C. Naphthalene was measured before and after purging the Columns. The mobile phase is acetonitrile: water = 60/40 (v/v).

In Figure 2, below, test of resistance to alkalinity was tested by purging the Columns with 40% acetonitrile/60% 20mM Na2HPO4, pH 9.4 at a flow rate of 1.0mL./min. and 40C.

In Figure 3, below, aniline derivatives were measured before and after purging the Column. Mobile phase conditions are the same as in Figure 2 above. The value of N and K' were calculated from N,N-Dimethylaniline.