1. There are no peaks in the chromatogram.

The system did not sample or decompose samples; Pump is not injected or mobile phase is used improperly; The detector settings are incorrect; According to the causes of the above situation, we can make corresponding adjustments.

2. One peak or several peaks are negative peaks.

The absorption background of mobile phase is high; Introducing air in the sampling process; The absorption of sample components is lower than that of mobile phase.

3. All peaks are negative.

The signal cable is connected reversely or the detector output polarity setting is reversed; The optical equipment has not reached equilibrium.

4. All the peaks are wide.

System imbalance; The polarity of dissolved samples is quite different from that of flowing samples. Incorrect column size and type selection; The chromatographic column or protective column is polluted or the column efficiency is reduced; The influence of temperature change.

5. The peak value is smaller than expected

The viscosity of the sample is too large; Sample failure or sample volume error; The detector is not set correctly. Incorrect cycle volume; Detecting pool pollution; There is something wrong with the detector light.

6. The appearance of bimodal or acromion

The sample size is too large; The sample concentration is too high; The column head of the protective column or chromatographic column is blocked; Pollution or failure of protective column or chromatographic column; The column collapses or forms a short channel.

7. Outstanding peak

The sample volume or concentration is high, and the solvent for dissolving the sample is more polar than the mobile phase; Contamination or failure of protective column or chromatographic column.

① Low column temperature: increase column temperature; ② Improper selection of sample solvent: use mobile phase as sample solvent; ③ sample overload: reduce the sample content; ④ chromatographic column is damaged: replace chromatographic column.

8. Tailing peak

The chromatographic column is overloaded, reducing the sample size; Increase the column diameter and use a higher capacity stationary phase; Peak interference, cleaning and filtering samples; Adjust the mobile phase; Under the action of silicon hydroxyl group, triethylamine was added, and the concentration of buffer solution or salt was increased by alkaline passivation column, and the pH value of mobile phase was reduced. If the sintered stainless steel in the column fails, replace it; Add an online filter to filter samples; If the dead volume or the volume outside the column is too large, try to reduce the connection points; Try to use connecting pipes with smaller inner diameter; The efficiency of chromatographic column decreases, and the chromatographic column is replaced; Protective column is used for regeneration column.

9. There is a flat-headed peak

The detector settings are incorrect; The sample volume is too large or the sample concentration is too high.

10. Ghost peak appears

The residual peak of the injection valve may be the residual of the last sample. After each injection, use enough time to balance and clean the system; There are unknown substances in the sample, which improves the pretreatment of the sample; If the mobile phase is polluted, replace it with a new one and use it as soon as possible. The overnight mobile phase should be filtered when it is used again; Use HPLC-grade reagents as much as possible; There are small bubbles in the flow channel. Open the purge valve and increase the flow rate to eliminate them.