What happens if my sample solvent is stronger than my mobile phase?

We do not recommend injecting in a stronger solvent because it usually results in peak distortion, broadening, poor sensitivity, and shortening of retention times.

This happens because some analytes will tend to travel too quickly through the column, instead of eluting in a symmetrical band.

If you absolutely must do this, keep the volume as small as possible and make sure the solvents are miscible.