Dear Tom,
Thank you for reply.
- The peak shape deteriorated gradually
- mostly shoulder
- There're five peaks in the chromatogram ( main peak -R+S-, İmp A,B,C,D and E. We observed all the same problem for all peaks
- There were no change in retention times
As you explained bellow, it should be physical problem. Using pre-column filter could resolve problem. We'll try and let you know result. Thanks
Also, we observed that there was precipitate in MP-A (ammonium acetate probably). Is there any tips to prepare/store MP contain ammonium acetate? We prepare MP daily and filter from 0.45 micron filter.
tom jupille wrote:
More information would help:
- did the peak shape deteriorate gradually or abruptly?
- "peak shape" is a bit vague; is it simply tailing or something else (e.g., a shoulder0
- are all the peaks in the separation showing the same problem (or are some peaks still well-formed)?
- was the problem accompanied by changes in retention time?
The reason for asking all of this: if it's a "physical" problem (column headspace or partially-blocked frit) is should affect all the peaks in the separation in a similar manner, and the retention times should be unchanged. If it's a headspace, it will usually come on gradually; a partially-plugged frit will usually come on abruptly.
If it's a "chemical" problem (e.g., deterioration of the bonded phase), it is likely to affect some peaks more than others, and the deterioration is usually gradual.