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Discussions about HPLC, CE, TLC, SFC, and other "liquid phase" separation techniques.
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in column H+ with water acidified mobil phase (H2SO4),flow of 0.6 ml/min and 55°C, i cannot separate lactose and ammonium citrate. can you help me. Thank you[/i][/b]
athebault
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- tom jupille
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From your conditions, I assume you're talking about a cation exchange column in the H+ form. Those columns are designed and sold for fairly specific applications. The first thing I would do is to check with the manufacturer to find out if that column is supposed to separate lactose and citrate.
Things you can do to try changing the selectivity:
- change the temperature. The high-temperature is required for glucose (and glucose oligomers) on Ca++ form resins (otherwise you get partial separation of alpha and beta glucose), but as far as I know, not required on the H+ column.
- change the pH. The degree of ionization of citrate will affect its retention, lactose is neutral.
- try adding organic modifier (ACN). That will tend to make everything elute faster, but it can also change selectivity.
Good luck, and let us know how it works out.
Things you can do to try changing the selectivity:
- change the temperature. The high-temperature is required for glucose (and glucose oligomers) on Ca++ form resins (otherwise you get partial separation of alpha and beta glucose), but as far as I know, not required on the H+ column.
- change the pH. The degree of ionization of citrate will affect its retention, lactose is neutral.
- try adding organic modifier (ACN). That will tend to make everything elute faster, but it can also change selectivity.
Good luck, and let us know how it works out.
-- Tom Jupille
LC Resources / Separation Science Associates
tjupille@lcresources.com
+ 1 (925) 297-5374
LC Resources / Separation Science Associates
tjupille@lcresources.com
+ 1 (925) 297-5374
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