Does LC Column Storage Really Matter?

When you are finishing up for the day and shutting down your instrument, you may ask yourself, “is storing my column in the appropriate mobile phase conditions really necessary?” It may add an extra step at the end of your testing or be something that you forgot about until after you get home, but the short answer is yes, column storage really does matter.

Just like choosing the right mobile phases to use on a specific column phase can optimize the life span of your column, proper mobile phase storage of your column after testing can increase the life span of your column as well. In the examples below, you can see the same method and analytes being analyzed on different lots of the same type of column.

Figure 1. Chromatogram from Column 1.

Figure 2. Chromatogram from Column 2.

Figure 3. Chromatogram from Column 3.

Table 1. Summary of Retention Times across the 3 Lots of Columns Tested.

Analytes	Column 1 (Figure 1)	Column 2 (Figure 2)	Column 3 (Figure 3)
Methionine	1.05	1.02	0.91
Homocysteine	1.17	1.14	1.03
Homocysteine-D3	1.16	1.13	1.02
Cysteine	1.60	1.59	1.47

The first column (Figure 1) is a newer column that has been stored under the proper conditions for the column. The second two were older, previously used columns found throughout the lab. While the chromatograms in Figure 1 and Figure 2 show similar retention times, based on the peak shapes, this column may have been stored under the wrong conditions. When looking at Figure 1 and Figure 3, not only is the peak shape drastically different, but there is a shift in retention as well. This is clear evidence that this column was not stored under the recommended conditions. The retention times of all three columns can be found in Table 1.

If you find an old column in the lab and throw it on your instrument to test retention times across different lots of the same column type, you may see drastically different retention times on the older column. This could be because the column was not stored properly before it was thrown in a drawer many, many months ago. However, when stored properly, columns can last for a very long time.

Most manufactures recommend storing your column with the proper mobile phases if you are going to be storing your column for longer intervals of time, but it is a good practice to get in at the end of testing every day. Columns should be flushed to remove any buffered, acidic, or basic components. To do this, flush the column with a solvent that is identical to the most recently used mobile phase, but does not contain any buffered, acidic, or basic components. Let this flush through your column for 10-20 column volumes.  For reversed phase columns, manufacturers recommend storage in some sort of mixture of methanol or acetonitrile with a maximum of 50% water. However, normal phase columns should be stored in nonpolar solvents such as 100% acetonitrile. 

It is also important to ensure that the column is plugged, and that the plugs are tight so the column will not dry out. Columns should also be stored between 15-30^oC.

If you are unsure of how to store your column, or what mobile phases are best, check the insert that came with your column, or reference online documentation to see how the column was stored when it arrived, and be sure to follow manufacturer’s column care usage and guidelines.