Dear all,

we try to obtain a "fingerprint" chromatogram of sulfobutylether-beta-cyclodextrin, showing the substitution profile of this charged carbohydrate derivate.

Chromatographic conditions are as follows:

column: Dionex AS11-HC (2 x 250 mm)
mobile phase: gradient 20 mM to 100 mM NaOH in 20 min
oven temperature: 30°C
analyte conc.: 5 mg/ml
detection: conductivity

We can separate 10 peaks but the resolution is bad: The result is a huge "mountain" with the peaks sitting on it.

How can we get baseline-resolved peaks? Reducing the analyte concentration wasn´t successful.

Many thanks in advance.

Anonymus

I haven't tried this compound, but it the sort of application that capillary electrophoresis excells at.

There are several possible explanations depending upon the specifics (you mentioned the concentrations that you used but not the injection volume). But even if I assume you are injecting less than five microliters years sample is probably too concentrated. I would start with a sample concentration an order of magnitude lower.

Second,the sample you describe is probably fairly complex with considerable variability in positional isomers. Try flattening out the gradient in the region where your analytes are eluting (you haven't indicated wherein the chromatograms they elute).