By Uberto on Tuesday, May 22, 2001 - 11:19 pm:
Dear all,
I have a problem recently in analysing avoparcin, an antibiotic using ion-pair chromatography. The mobile phase used is 2.5% acetic acid, 0.01M sodium heptane sulfonic acid-acetonitrile (88.5:11.5) (pH 4.0 by ammonia). The column is C18 column (4.6mmx25cm). I observe that the retention time is not stable, and rusting on the joint is also found. Is it because the ion-pair reagent is too corrosive? How could I stabilize the retention time? Need very long conditioning time? Please advise.
By Uwe Neue on Wednesday, May 23, 2001 - 02:41 pm:
With ion-pair reagents you need a long equilibration time to start, and then you want to keep the column in this mobile phase, without flushing it with organic solvent. Otherwise, you are back at the equilibration stage.
If this is not the problem, we need more information...
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