By Anonymous on Monday, September 27, 1999 - 05:18 pm:
Is it okay to wash reverse phase columns with water?
By tom jupille on Monday, September 27, 1999 - 10:50 pm:
Unless the manufacturer indicates that the column is specifically designed for use with 100% aqueous, the consensus seems to be "no". You probably won't damage the column, but it will take a loooong time to reequilibrate.
Check out the thread on "Washing column with 100% aqueous" in the May-July Archives section here on the forum for a more extensive discussion.
-- Tom Jupille / LC Resources
By Scott Fredrickson on Tuesday, September 28, 1999 - 02:47 pm:
This 'phase collapse' phenomenon probably explains some illogical data from years ago I had not thought about until now. We were running soil extracts (for the carbamate pesticide aldicarb, I believe) on a C18 gradient system, and after a couple days of work (25-50?? samples), the system would just go nuts, drifting all over the place. We could not get the system to re-equilibrate, even with a lengthy 100% ACN washout. However, overnight washing with 100% water, and then a few normal standard injections brought the system back to earth, and off we'd go for another batch of samples. I argued that water should theoretically not help, but it did....time, and time again, all summer long.
Apparently the phase collapse causes the column to ....well, maybe we ought to look the theory up. Is there a good reference paper on the topic? Perhaps the moderator could suggest one. I don't remember any particular problem getting the columns to perform after the water torture. However, using 100% water as the gradient start would probably cause problems. I think we tried that once, and it didn't work as we had hoped.
Those poor columns had relatively short lives (a few hundred injections, rather than a few thousand) thanks to the soil co-extractives we put on them, but we got the job done, and that was the bottom line.
If I run into this problem again, it would seem like a good idea to keep close records on what is going on so that column resolution, selectivity, recovery time, life expectancy, etc. can be documented, and intelligent decisions made. LC has come a long way since those days, thanks to the people at places like LC Resources.
By B.Buglio on Wednesday, October 6, 1999 - 06:45 pm:
For a really usefull article read "Compatability
of C18 HPLC Columns with Pure Aqueous Mobile
Phase" Reid and Henry, American Laboratory, 31.
July 19
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