Chromatography Forum

Hi,

I've got a little ionization problem with my analytes: When I'm recording a calibration curve of my analytes (5-1000 ng/ml) I get peculiar results. The curve is linear from 5 to 30 ng/ml and from 60 to 1000 ng/ml. But between these two zones there is a major bend in the calibration curve.
Does anybody of you know how I can eliminate the bend and get a real linear curve for the whole calibration range?

Dear Kazy,

What kind of samples do you inject; processed samples or straight dilutions of your analyte?

It also happens when I inject straight dilutions of my stock solution.

I suppose that the response at higher concentrations is less than at lower conc. In that case, you should try to optimize the ionisation in the source (other organic modifier, pH etc.), change the ionisation mode, limit the range of the calibration curve or introduce less analyte into the source by diluting your samples or limit the injection volume.

Good luck!