Column backpressure

[parya_m]

How can I find that the high backpressure of the column (c18) is related to packing deterioration or contamintion? in the other hand, how I can check the integrity of column packing?

[uzman]

Compare it with a same new column under exactly the same conditions. ( Same mobile phase , same flow , same temperature etc. )

[tom jupille]

How can I find that the high backpressure of the column (c18) is related to packing deterioration or contamintion?

Before blaming the column, however, it's a good idea to check for other potential blockages. I like to disconnect fittings starting at the end of the system and working my way upstream. You may find the blockage is at an in-line filter (you *are* using and in-line filter, aren't you?), or a transfer line, or the injection valve.

If it *is* the column, once a blockage has occurred, you can't tell for sure whether the cause was deterioration of the packing (e.g., because of an unfavorable mobile phase) or contamination from the sample. If you monitor the pressure over time, you can run a punctuated series of injections and plot pressure versus injection number and again versus total time. (http://www.lcresources.com/resources/TSWiz/hs390.htm).