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By Anonymous on Thursday, June 17, 2004 - 10:09 am:
hello,
When I prepare a solution of TFA 0,1%, the pH of it is less then 2. Is it necessary to use a column whose range of pH is from 0 to 8? The question is because this mobile phase is widely used and this kind of column is much more expensive than the common one (from 2 -
. What do you usually do?
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By MG on Friday, June 18, 2004 - 06:37 am:
I have used this amount of TFA with ordinary columns rated down to pH 2, even though the pH is a little lower than that. Just don't run at elevated temperatures, and flush out the TFA as soon as possible when your analysis is completed. I have not used TFA often enough to say for sure, but I am guessing that the column would have a shorter lifespan.
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By Anonymous on Friday, June 18, 2004 - 01:04 pm:
thanks, mg
does anyone have another experience with tfa?
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By Chris Pohl on Saturday, June 19, 2004 - 12:55 pm:
The long-term stability of bonded phase silica below pH 2 is certainly dependent upon the nature of the bonding chemistry, which is the basis for the aforementioned "expensive" columns. But the long-term stability is also dependent upon other factors, as well, including: operating temperature and solvent content, with increasing solvent content resulting in better column stability and increasing temperature resulting in poorer column stability. So, if you can stay away from high water content mobile phases you'll get significant improvement in column life. If you can operate at sub-ambient temperatures (or at least avoid elevated temperature), this will also improve your column life.
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By Anonymous on Wednesday, June 23, 2004 - 02:09 pm:
txs chris
hello,
When I prepare a solution of TFA 0,1%, the pH of it is less then 2. Is it necessary to use a column whose range of pH is from 0 to 8? The question is because this mobile phase is widely used and this kind of column is much more expensive than the common one (from 2 -
. What do you usually do?
-------------------------------------------------------------------------------------------------------
By MG on Friday, June 18, 2004 - 06:37 am:
I have used this amount of TFA with ordinary columns rated down to pH 2, even though the pH is a little lower than that. Just don't run at elevated temperatures, and flush out the TFA as soon as possible when your analysis is completed. I have not used TFA often enough to say for sure, but I am guessing that the column would have a shorter lifespan.
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By Anonymous on Friday, June 18, 2004 - 01:04 pm:
thanks, mg
does anyone have another experience with tfa?
-------------------------------------------------------------------------------------------------------
By Chris Pohl on Saturday, June 19, 2004 - 12:55 pm:
The long-term stability of bonded phase silica below pH 2 is certainly dependent upon the nature of the bonding chemistry, which is the basis for the aforementioned "expensive" columns. But the long-term stability is also dependent upon other factors, as well, including: operating temperature and solvent content, with increasing solvent content resulting in better column stability and increasing temperature resulting in poorer column stability. So, if you can stay away from high water content mobile phases you'll get significant improvement in column life. If you can operate at sub-ambient temperatures (or at least avoid elevated temperature), this will also improve your column life.
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By Anonymous on Wednesday, June 23, 2004 - 02:09 pm:
txs chris
