No peak or abnormal signal

Inspection sequence: Check one by one from the injection needle, injection port to the detector.

Key point: Confirm whether the syringe is blocked; Check if the graphite gaskets of the injection port and detector are securely fastened; Observe whether the detector outlet is unobstructed (if the discharge outlet of the ECD detector is blocked, it will cause gas to be unable to flow).

Case: A certain instrument experienced abnormal column head pressure due to ice blockage at the ECD discharge port. After replacing the carrier gas, it returned to normal.

Baseline fluctuation or drift

Cause analysis: Insufficient purity of carrier gas, aging of injection pad, contamination of liner or unstable temperature control.

Troubleshooting steps: Check the purity of the gas source; Replace the injection pad; Clean the lining tube; Calibrate the temperature sensor.

Case: Insufficient purity of the newly replaced carrier gas resulted in severe baseline shaking. The problem was resolved after replacing the qualified carrier gas.

Difficulty igniting or unstable flame

Inspection content: hydrogen and air flow settings; Is the ignition wire red; Is there contamination in the detector.

Solution: Adjust the gas flow rate; Clean or replace the ignition wire; Perform aging treatment on the detector.

2、 Daily maintenance strategy

Maintenance of pneumatic system

Regularly check the status of the gas source (gas cylinder, gas generator) and purifier, replace the dehydration filter, activated carbon and other fillers.

Use an input gas pressure gauge to monitor gas input and check for leaks or blockages in the gas circuit.

Cleaning of injection port and detector

Injection port: Clean the injection chamber nut, spacer purge outlet and other components weekly, and rinse with ethanol or acetone.

Detector: Choose the cleaning method based on the degree of contamination (such as injecting distilled water or ethanol into the FID detector for cleaning).

Column maintenance

Regularly age the chromatographic column to remove volatile substances and avoid loss of the stationary phase.

Aging conditions: With the carrier gas entering the chromatographic column, set the column box temperature to around 30 ℃ at the maximum operating temperature of the chromatographic column and age for more than 10 hours.

Instrument calibration and performance evaluation

At least once a year, a performance evaluation of the chromatographic column should be conducted to check indicators such as column efficiency and peak width.

Calibrate detectors quarterly (such as FID using standard gases for response value calibration).