Baseline

[Tammy Nguyen]

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

[ntruong]

Does the baseline drop in the blank run as well?

[malaka50]

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.

[Tammy Nguyen]

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

[michaldousa]

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.