No current with phosphate buffer - Chromatography Forum

No current with phosphate buffer

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Hi all,
I want to separate some basic componds. I prepared 100 mM phosphate buffer (pH 2.0) and I used 50 um capillary (48.5 cm). Everything was OK, I got peaks. Now I have to use another CE instrumetation (I usually use it for anion analysis and it works perfectly).
But suddenly there is no current at all at +20 kV or the currrent is too low (4-5 uA). Moreover, if I observed current it desappeared in 5-10 min.
I tried to remade the buffer, to exchange to capillary (both 50 and 75 um), to flush longer, to vary the applied voltage. No stable current, no peaks.

Could you please recommend something?

If you say there is no problem with the instrument, i can only think at dirty electrodes or bubbles/particles in the buffer. Have you degassed and filtered the buffer?
Man this is an old topic. :) I used to have a lot of problems keeping the capilliary on the cartridge without it touching and causing a leakage current. A trick I would do is to tape the entire capilliary with a piece of scotch tape to insulate it. After this you can wind it anyway you want to.
3 posts Page 1 of 1

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