HPLC Troubleshooting - No Peaks

If your chromatogram no longer has peaks being displayed some common causes could be related below. 

Causes	Solutions
Detector setting issue	- Check the detector lamp is turned on. - Check electrical cables are connected. - Check the life span of the lamp and replace if exceeded hours. - Ensure an appropriate detector is used for the physico-chemical properties of the analyte. - Check the method procedure uses appropriate detector settings for the compounds.
Compounds retained longer than run time in method conditions	- Check mobile phase composition is correct. - Check correct column is being used. - Increase run time. - Increase solvent strength.
Sample issues	- Ensure the sample hasn’t degraded. Prepare fresh samples. - Ensure the sample is in the correct position in the autosampler. - Sample adsorption issue.
Blocked needle	- Try to clear the blockage or replace the needle. Address why the needle blocked (i.e. blocked by septa or poor sample preparation).
Instrument	- No mobile phase flow, possibly purge valve left open. - Purge the system to remove possible air bubbles in pump. - Purge injector to remove air bubbles in metering pump.