I am working with a gradient elution with an eluant with TBABR and phophate sodium salts for the Ph 7.2. I have a lot of artefacts peaks in the baseline. These are very large and not like chromatography peaks. I don't find what is the origine of this problem. I work with WATERS SYSTEMS.
Can somebody help me ?

Does this happen when you have injected something, or just equilibrating?

What wavelength are you working at? Bromide absorbs in the ultraviolet (even at 254 nm) and maybe the source of one of your artifact peaks. Also, tetrabutylammonium bromide is often contaminated with a number of other impurity anions, many of which absorb in the ultraviolet. I would use an HPLC grade tetrabutylammonium phosphate salt or buy HPLC grade tetrabutylammonium hydroxide and neutralize with HPLC grade phosphoric acid. Both are available from a number of sources but I know Fluka sells them both.

To A.Nonymous

These peaks appears each time I start the gradient elution even I don't inject a sample, when I do a blank injection. Sometimes I have no problems and the baseline is very regular and sometimes this peaks appears. These are more important on the fluorimeter detector than on the UV dectector.It is more sensitive.I work with both detector. Thanks to Chris I will try to change my TBABR.

Have you already tried to change your screwcaps, because there are caps with contamination.

Do you observe these extraneous peaks when you use other columns with this mobile phase? I have seen differences in different columns when a strong gradient is used, I assume these extraneous peaks have varying retention times from run to run? If they have the same retention time every time they appear,I would suspect carryover from your autoinjector.

Best regards,

Wayne