Chromatography Forum

Hi

if a column used for analysis of a particular compound/sample (lets say sample ‘x’) and then the same column is used for analysis of another compound (say, sample ‘y’) will it behave differently than using a new column of same type??

i.e will there be a “footprintâ€

sometimes new columns do not behave as "good" as the ones that have been used for some times (injections), but this does not happen so often

the best way is to check but
- columns age so older column could have lower efficiency
- if the column was used with ionpair reagent it could behave differently (a bit) than one which was not used with ionpair
- older chiral columns should have been used with one pH range (acidic or basic), this shouldn't be problem with newer ones

it all comes down to column history, nature of the sample analysed and eluents used, and most importantly for what you are doing now

I consider it as GLP to use dedicated column for routine analysis of compound(method), but I use what I have for early method development and this are sometimes new and sometimes old columns

The column is good if method criteria are met to summarize

If your sample x and/or the run method leaves something behind, or if it causes reaction with the column, you may get an influence on the behavior of sample y. There is no mystry to it.

Under normal circumstances, the column is not affected by the sample nor the mobile phase, and you can use the column for different assays. A contamination by components of the sample that are strongly retained and difficult to remove is part of the column aging process and will for the most part affect one assay in a similar way as another assay.

A possible exception to this rule is the use of ion-pair reagents. There have been consistent reports about selectivity changes after use of ion-pair reagents. I have not seen such a problem myself, but I can't exclude it either.

If a column is used outside the specified stability range, then changes may be more visible with one assay compared to another one. For example, if you use a column specified to pH 2 at pH 1.5 for the retention of acidic analytes, you may not see any changes to the column as it is used. If you use the exact same column afterwards at pH 7 for the assay of basic analytes, you are likely to see very large differences compared to a new column of the same type.

I'll chime in by agreeing with Uwe, and then noting that he hedged: "Under normal circumstances" and "for the most part". The *possibility* of problems is always there.