Volume-load capacity in fast-gradient liquid chromatography effect of sample solvent composition and injection volume on chromatographic performance

We studied the effects of sample solvent composition and injection volumes on the chromatographic performance of ODS-bonded silica columns under fast-gradient running conditions. Chromatographic performance is compromised as a function of both sample injection volume and sample solvent strength, with earlier-eluting analytes being much more affected than later-eluting ones. In general, when injecting samples dissolved in a strong solvent, performance was improved by diluting the strong injection solvent and injecting a proportionally larger volume. Volume loading capacity can be increased by using a longer column, or by using a column of equivalent length, but with a larger inner diameter. Data also suggest that sample solvent strength, not viscosity, is responsible for the noted effects.