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Normal Phase Efficiency Indicators

Discussions about HPLC, CE, TLC, SFC, and other "liquid phase" separation techniques.

4 posts Page 1 of 1
Does anyone have indicator recommendations for normal phase efficiency measurements? I am looking for those that are "customary" or usual or generally recognized.

Thank you
Doug

toluene
-- Tom Jupille
LC Resources / Separation Science Associates
tjupille@lcresources.com
+ 1 (925) 297-5374

Tom,

When toluene is used as the efficiency indicator for a nomral phase column, what mobile phase is recommended for the test? If a normal phase mobile phase (high organic solvent) is used, toluene should elute close to the void in which case it won't be a good probe. It seems more reasonable to use a polar compound such as urea or uracil as probes for normal phase chromatography. Would you please elaborate on this? Thanks!
Xiaodong Liu

XL, remember that solvent strength in normal phase is the reverse of that in reversed-phase (i.e, water is a very strong solvent). In the event, a typical mobile phase would be a few percent dichloromethane (strong solvent) in hexane (weak solvent), with the percentage adjusted to give a reasonable k' (the exact value, obviously, will depend on the column).
-- Tom Jupille
LC Resources / Separation Science Associates
tjupille@lcresources.com
+ 1 (925) 297-5374
4 posts Page 1 of 1

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