Column aging - Huaqiang Electronic Network

Capillary Column Aging Procedure

The purpose of column aging is to stabilize the stationary phase on the inner surface of a capillary column or on the support material in packed columns. When a new column is used, the bonding between the stationary phase and the carrier is not strong enough, and it may begin to degrade at high temperatures. This can lead to baseline instability, noise, and poor separation performance.

To prevent this, the column should be heated at a temperature close to its upper temperature limit for a certain period. This process helps remove weakly bonded components, ensuring that the stationary phase remains intact during subsequent analyses. Additionally, aging can help eliminate any residual contaminants that may have accumulated over time, especially in long-used columns.

During the aging process, the column temperature is gradually increased to a constant value—typically the maximum operating temperature. In some cases, it may be raised by 10–20°C above the normal operating temperature, but it must never exceed the column’s upper temperature limit. Exceeding this limit can permanently damage the column. It is also important to avoid slow temperature programming, as this can affect the effectiveness of the aging process.

Once the desired temperature is reached, the baseline should be monitored. Initially, the baseline will rise and then start to decrease within 5–10 minutes. The baseline should continue to stabilize over the next 30–90 minutes. If the baseline remains unstable after 2–3 hours or shows no significant decline after 15–20 minutes, there may be an issue such as a leak or contamination in the system.

If problems are detected, the column temperature should be reduced below 40°C immediately, and the system should be checked and repaired as soon as possible. Continuing the aging process under these conditions can further damage the column without achieving a stable baseline. Also, excessive aging time can shorten the column’s lifespan, so it is important to follow recommended procedures carefully.

Columns with polar stationary phases or thicker coatings generally require longer aging times, while columns with less polar phases or thinner coatings may need less time. The exact procedure may vary depending on the type of column and manufacturer recommendations. Always refer to the column’s operating manual for specific instructions.

If the column is aged without being connected to the detector, the end of the column may be damaged. In such cases, it's advisable to cut off the first 10–20 cm of the column before reconnecting it to the detector.

The temperature limit refers to the range in which the column can operate effectively. Operating below the lower temperature limit may result in poor separation and peak shape, but it usually doesn’t harm the column itself. The upper temperature limit typically has two values: one for constant temperature use (with no time restriction), and another for programmed temperature increases (usually limited to 10 minutes or less). Exceeding the upper temperature limit can significantly reduce the column’s lifetime.