Peaks have flat tops

If an analysis shows peaks with flat tops, check the following:

Solvent delay is too short

If the analyzer is on when the solvent peak elutes, the detector may saturate. Make sure the solvent delay is long enough to miss the solvent peak.

Incorrect display scale

If the flat peak top is at the top of the display, the scale may be incorrect. Change the scale.

Injection size too large

A large injection can saturate the column or the detector. Reduce the injection size or reduce the sample concentration.

Electron multiplier voltage is too high

Reduce the electron multiplier voltage by 50 or 100 volts. If performance improves, continue to adjust the electron multiplier voltage until you find the optimum setting.