Chromatography Forum

Hi all,

My baseline is not a straight line. After the peak eluted, the baseline is not coming back at zero; instead, it keeps moving downward a little bit more. The peak looks like having a long tailing, and the baseline looks like having a valley. I have 1mL of triethylamine/L.

Please help me how to get rid of it.

Thank you,
TN

Does the baseline drop in the blank run as well?

clean the column, maybe back flush at a low flow rate.

run gradient 95% water to 95% acetonitrile.

condition column for at least an hour, maybe longer with the TEA mobile phase.

The valley drops in resolution solution only, not blank nor STD. SA. Maybe one of the components in reso. causes it.

I didn't clean the column yet since I've seen a nice blank after I ran the resolution; will try some time today.

Thanks, all.
TN

I have too little information. How is composition of mobile phase (first of all pH of mobile phase)? Ion-pair reagents are use? Try to equilibrate column for a longer time.