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By Ionman on Wednesday, July 14, 2004 - 07:37 pm:
Hi
I need your opinions regarding the practice of fliping a columns to resolve tailing and shouldering peaks. I was trained never to reverse a column, unless you know that it has reached it end. But in the lab that I work in now, it is a common practice to reverse and flush a column with 50% MeOH 50% H20, and then reverse it again and run it under normal conditions. And it work like a charm. My co-workers informed me that the Waters service man, said it fine to do so. Please let me know what is the correct way to correct for shouldering and tailing, besides altering mobile phase and column temp.
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By MK on Thursday, July 15, 2004 - 01:37 am:
replacing the column / use pre-column.
revers flushing might be fine unless you haven't created a void to column head. If so, you will move and probably brake the column packing by reverse flushing.
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By tom jupille on Thursday, July 15, 2004 - 09:28 am:
Depends on the circumstances. Some years ago I developed a method that called for reversing the column at the beginning of every day. Crud from the matrix would gradually build up on the head of the column and the operating pressure would rise gradually during the day. Reversing the column on a regular basis was more cost-effective than adding a cleanup step or a guard cartridge.
As a fix for peak shape problems, reverse-flushing the column is certainly one of the first things to try. If the problem is caused by a chunk of particulate debris on the inlet frit, that should cure it. If the cause was a headspace, then backwashing will "fluff" the packing (how's that for technical terminology?) and sometimes provide a *temporary* fix. If the problem recurs, then the column should be replaced.
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By Chris on Thursday, July 15, 2004 - 12:03 pm:
I agree with the above, however I would always make sure you prevent the waste from entering the detector as any particulates flushed off can cause build ups and blockages in the detector cell.
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By tom jupille on Thursday, July 15, 2004 - 01:19 pm:
Good point, Chris (thanks!)
Hi
I need your opinions regarding the practice of fliping a columns to resolve tailing and shouldering peaks. I was trained never to reverse a column, unless you know that it has reached it end. But in the lab that I work in now, it is a common practice to reverse and flush a column with 50% MeOH 50% H20, and then reverse it again and run it under normal conditions. And it work like a charm. My co-workers informed me that the Waters service man, said it fine to do so. Please let me know what is the correct way to correct for shouldering and tailing, besides altering mobile phase and column temp.
-------------------------------------------------------------------------------------------------------
By MK on Thursday, July 15, 2004 - 01:37 am:
replacing the column / use pre-column.
revers flushing might be fine unless you haven't created a void to column head. If so, you will move and probably brake the column packing by reverse flushing.
-------------------------------------------------------------------------------------------------------
By tom jupille on Thursday, July 15, 2004 - 09:28 am:
Depends on the circumstances. Some years ago I developed a method that called for reversing the column at the beginning of every day. Crud from the matrix would gradually build up on the head of the column and the operating pressure would rise gradually during the day. Reversing the column on a regular basis was more cost-effective than adding a cleanup step or a guard cartridge.
As a fix for peak shape problems, reverse-flushing the column is certainly one of the first things to try. If the problem is caused by a chunk of particulate debris on the inlet frit, that should cure it. If the cause was a headspace, then backwashing will "fluff" the packing (how's that for technical terminology?) and sometimes provide a *temporary* fix. If the problem recurs, then the column should be replaced.
-------------------------------------------------------------------------------------------------------
By Chris on Thursday, July 15, 2004 - 12:03 pm:
I agree with the above, however I would always make sure you prevent the waste from entering the detector as any particulates flushed off can cause build ups and blockages in the detector cell.
-------------------------------------------------------------------------------------------------------
By tom jupille on Thursday, July 15, 2004 - 01:19 pm:
Good point, Chris (thanks!)
