If a sample cannot be dissolved in 90:10 water/acetonitrile, for a reversed-phase method, can I use a higher percent acetonitrile to dissolve it prior to injection? - WKB92020

ENVIRONMENT

• Sample preparation

ANSWER

Yes, provided the percent of acetonitrile is not so high as to cause strong sample solvent effects.

ADDITIONAL INFORMATION

It is always best to prepare samples in a diluent that has a ratio of aqueous to organic similar to that of the initial mobile phase conditions.

If this cannot be done, it is okay to increase percent organic, but not too high. You would need to study how high you can go before you see strong sample solvent effects. These effects cause the peak to partially elute during sample load (which causes peak shape problems).

If you have a problem with sample solubility in high aqueous mobile phase, consider reviewing the following document:

At-Column Dilution Application Notes