Use of a strongly basic mobile phase is not recommended for any silica based HPLC column because the underlying silica of the stationary phase is prone to dissolution at pH above 8 with a strong ionic strength. This may seem problematic for some analytes that you want to use in Aqueous Normal Phase (ANP).

Folic acid for example is not appreciably soluble in neutral to acidic conditions. However, you can use a basic diluent for the sample only and still use a mild or acidic pH mobile phase (ANP). The small volume of the sample plug will not cause significant dissolution of the stationary phase and will allow for accurate quantitation of the analyte.