The column pressure rises the column into the U filter and is blocked by the mobile phase or the particles in the sample.
The sample components precipitate on the filter to block the filter. Remove the filter from the inlet fitting and ultrasonically clean it with a 1 : 1 nitric acid solution for 5 min , then remove the water with water and methanol.
Sample and mobile phase use 0 . A 45 μm filter removes trace impurities.
The sample was prepared using the mobile phase as a solvent.
The new column has a low dead volume outside the column.
The sample does not dissolve well in the mobile phase, affecting the mass transfer process. Replace the connecting tube and reconnect the column to reduce the dead volume.
Dissolve the sample using a suitable mobile phase or using a mobile phase.
The old column has low column efficiency, poor separation, and the column inlet bed collapses. The filler is lost by the mobile phase dissolution. Partial recovery can be achieved by filling the column with the same type of filler.
For silica gel fillers, the mobile phase PH value is in the range of 2-7 , otherwise it may be dissolved.
Old columns have poor column efficiency and sometimes double peaks. The entry filler is contaminated by deterioration. Rinse with a strong solvent.
The contaminated bed is scraped off, and the effect of filling the column with the same type of filler can be partially restored.
If the pollution is serious, it will be discarded or refilled.
After the new column is connected to the instrument, the column head leaks. The pressure ring of the connecting pipe between the column joint and the instrument is not deformed enough. Tighten 1/4 turn clockwise with a wrench until no leakage so far.
After the new column is connected to the instrument, there is no column pressure drop to start the instrument. The column is left for too long and the liquid filled in the column has evaporated. Continue to open the pump and replace the gas in the column with the mobile phase.
After the new column is connected to the instrument, small bubbles appear continuously at the detector outlet.
   1 Ibid.
　　 2 The mobile phase is not completely degassed. Especially the MeOH / H20 system is prone to bubbles due to hydrogen bonding. 1 Ibid.
　　 2 After the mobile phase is prepared, it must be degassed.
After the new column is connected to the instrument, the pressure drop of the column increases continuously, even exceeding the withstand voltage limit of the instrument. The column inlet filter is blocked by solid particles ( or poisoned)
Bacteria blocked ) . Replace or clean the column inlet filter; use 0 . The mobile phase was filtered through a 45 μm filter membrane to remove fine particles.
The number of injections increases and the column pressure drop increases gradually. 1 The sample contains tiny particles that are insoluble in the mobile phase.
　　 2 The sample precipitated minute crystals in the mobile phase. 1 with 0 . The sample was filtered through a 45 μm filter membrane.
　　 2 It is recommended to use a mobile phase to dissolve the sample.
Used - after a period of time, column degradation, poor separation. The 1 column packing is dissolved by the mobile phase and is lost.
　　 The 2 column packing is contaminated with sample impurities. 1 It is recommended to use the column. If the bed is collapsed, fill it with the same type of packing.
　　 2 It is recommended to use a guard column or flush the column with a strong solvent to remove contaminating impurities.
After the column has been used for a period of time, the efficiency of the column decreases. The column inlet bed is contaminated to degrade the column packing. Rinse with a strong solvent to remove impurities.
The column used - after a period of time, column degradation occurs peak tailing. The column entrance bed is contaminated. Rinse 20-30ml with a strong solvent and discard if the effect is not obvious.
The increase in injection volume is not proportional to the increase in peak area. That is, the injection volume and peak area are not linear. The solubility of the sample in the mobile phase is small, and only part of the sample is washed by the mobile phase as in the column and the other part is deposited on the column population. 1 Dissolve the sample with the mobile phase.
　　 2 The concentration of the sample should not be too large.
　　 4 injection volume should not be too large.
When buffer is used as the mobile phase, the column pressure drop rises rapidly. Caused by mold growth. 1 Add toxic substances to the mobile phase or add sodium chloride to prevent mold growth.
　　 2 After the end of the experiment, rinse with pure water and then rinse with 20-30 ml of MeOH .
When using a 5 μm particle packed column, the column pressure was higher with MeOH / H20 as the mobile phase. The viscosity between MeOH and water increases due to hydrogen bonding. The column pressure can be lowered by an acetonitrile/water system, and the separation efficiency is better.
A column that has been placed for a long time has a double peak. The column bed appeared to be dry. When the column is placed, it is best to fill it with the corresponding solvent to prevent large mechanical vibrations, such as cracking of the bed.
There are many impurity peaks when the mobile phase washing strength is weakly fading. Strong solvents flush out impurities that cannot be washed out by weak solvents. Does not affect the performance of the column.
After the column is used for a while, the retention value is gradually shortened. The loss of the stationary phase in the column.
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