Peak splitting or doubling

1

Column overload

Reduce the injection volume or dilute the sample.

Switch to a column with a higher sample capacity (increase length or diameter).

2

Injection solvent effects

If possible, use the starting mobile phase composition or weaker solvents as the injection solvent.

Ensure that the injection solvent is miscible with the mobile phase and causes no salt precipitation.

Reduce the injection volume.

3

Interfering component

Use sample preparation, such as filtration, solid-phase extraction (SPE), or centrifugation, to eliminate interfering contamination peaks and simplify the matrix in general.

If the interfering component is suspected to be from the previous injection, use gradient elution that ends at a relatively high organic composition or increase the starting organic composition, extend the run time, or switch to a stronger organic modifier.

4

Flush and, if necessary and allowed by the supplier, backflush the column.

Replace the column if necessary.

If using a guard column or inline filter, replace it.

5

Reverse the column direction if allowed by the supplier. If all peaks show poor peak shape, replace the column.

6

Worn injection valve rotor seal

Replace the rotor seal in the injection valve.