Usage Precautions for Welch Sugar Columns

Precautions for Using Welch Sugar Columns

Welch Sugar Columns are tightly packed with resin in an expanded form. If the sample has been properly pre-treated, most issues are related to damage to the resin packing.

Main Concerns for Sugar Column Packing:

1. Sudden Increase or Decrease in Column Pressure: Abrupt changes in pressure can damage the packing material.

2. Pressure Exceeds Maximum Tolerance (14 MPa): Increased pressure beyond the packing's maximum tolerance can lead to damage.

3. Organic Solvents Inability to Enter the Column: If organic solvents cannot flow through the sugar column, it can cause issues with performance.

4. Large Temperature Differences in Packing: Significant temperature variations can affect the integrity of the packing material.

Detailed Breakdown:

Sudden Increase or Decrease in Column Pressure

• Principle: The expanded resin packing is very fragile. Sudden drops or increases in pressure can cause the packing to break or shift within the chromatography column, damaging the column bed and altering the chromatographic retention behavior. Additionally, broken packing may be carried to the column’s outlet end screen, blocking the screen and further increasing column pressure.

What Causes Sudden Changes in Column Pressure?

• Issues with Check Valves: Problems with check valves can lead to pressure fluctuations, so it’s important to regularly check if the instrument is functioning properly.

• Blocked Inline Filters or Guard Columns: Accumulation of particulates in inline filters or guard columns can cause a rise in back pressure.

• Excessive Pulsation: Large pulsations can lead to sudden pressure changes, so flow rate adjustments should be made gradually.

• Other Causes:

  • Issues with the mobile phase
  • Problems with the pump
  • Overloading the injection volume
  • System leaks
  • Changes in room temperature.

Column Pressure Exceeding the Maximum Tolerance of the Packing

• Flow Rate: The maximum flow rate should not cause the pressure to exceed 14 MPa.

• Contaminated Inline Filters or Guard Columns: If these components are clogged, the filter or column core needs to be replaced.

• Blocked Sugar Column: If the sugar column itself becomes blocked, it should be regenerated and cleaned according to the instruction manual.

Organic solvents should not enter the sugar column.

Principle : The swelling coefficient of the sugar column packing material varies in organic solvents, which can cause the column bed to collapse, leading to column damage.

Large temperature differences in the packing material

Principles :

1. Uneven thermal expansion and contraction : When there is a significant temperature difference in different parts of the packing material, the expansion and contraction due to temperature changes will vary. This uneven thermal expansion and contraction can create pressure between the packing particles, potentially causing them to crack, deform, or loosen their connections, thereby damaging the structure of the column.

2. Impact on stationary phase stability : Drastic temperature changes may affect the chemical stability of the stationary phase in the sugar column. For example, certain chemical bonds may break due to thermal stress, altering the chemical properties of the stationary phase, which could then affect its ability to separate and retain samples.

3. Column bed collapse : A large temperature difference may cause excessive shrinkage of some packing material, leading to a partial collapse of the column bed. This can disrupt the uniform distribution of the packing material within the column, affecting the flow path and velocity of the mobile phase, resulting in decreased column efficiency and rendering the column unusable.

4. Bubble formation: Rapid temperature changes may alter the solubility of gases in the mobile phase, leading to bubble formation. These bubbles can interfere with the normal flow of the mobile phase within the column, increase pressure fluctuations, and damage the column. For instance, running a sugar column in a high-temperature environment followed by rapid cooling, or sudden heating in a low-temperature environment, can easily cause these issues, ultimately leading to column damage.

These are all factors that can cause column bed damage, so it's important to avoid related improper operations:

1. To prevent organic solvents and bubbles from entering the sugar column, flush the entire chromatography system with water before connecting the sugar column.

2. Before the column temperature reaches the set value, set the flow rate to 0.2-0.3 mL/min to avoid excessively high column pressure.

3. When the column temperature reaches the set value, increase the flow rate to the analytical flow rate. Change the flow rate in increments of 0.1 mL/min, and wait for the column pressure to stabilize before increasing the flow rate further. This avoids pressure pulses that could damage the column; similarly, reduce the flow rate in decrements of 0.1 mL/min.

4. The maximum flow rate should not cause the pressure to exceed 14 MPa.

5. After use, be sure to lower the column temperature to room temperature before stopping the pump, removing the column, and storing it in a refrigerator at 4°C.

6. After removing the column from the refrigerator, allow it to return to room temperature before using it on the instrument and increasing the column temperature. This prevents column bed damage due to large temperature differences.

7. Fully degas the mobile phase to ensure a stable baseline.

8. After each use, thoroughly flush the column with distilled water to replace any salt-containing mobile phase. If the column will not be used for an extended period, store it according to the recommended storage procedure.

Welch Sugar Column Profile

Welch Materials has introduced two polymer-based ion exchange columns: the H-type and Ca-type sugar columns. The H-type sugar column is primarily used for the separation of organic acids and is the specialized column for Ribavirin testing in the Chinese Pharmacopoeia. The Ca-type sugar column excels in the separation of polysaccharides and polyols.

Chromatographic Column Parameters

For instructions on new column activation, routine flushing, storage methods, and regeneration methods, please refer to the Welch Liquid Chromatography Column Manual.