To confirm the system sensitivity, use the manual injector first. If this is an issue of the autosampler, please see the autosampler manual.
1. Ensure the pump pressure is within a normal range.
2. It is possible that there is no communication between the data acquisition and detector. Please check the cable connections between HPLC and EPC-500. If the baseline of the chromatogram is extremely flat or just digital noise, this may be the cause.
3. The sample may not have been injected. To determine if the sample was injected, check if the front peak is present and the well plate volume. If the large front peak is not present and the well plate volume remains the same, it may be due to an injection problem. Check to ensure the autosampler needle is drawing from the bottom of the well plate. Try injecting your sample using the manual injector to determine if it is a problem with the autosampler (be sure to change the autosampler valve to Load position). If the drain tubing of the manual injector is clogged, the sample is not being loaded to the sample loop.
4. Your chromatogram record time may be too short. Try recording for a longer period of time, then the peak may be visible. Check the measured flow rate to ensure it matches the pump’s set flow rate. Measuring the volume in an eppendorf tube after one minute is suitable for this test.