Thanks very much for the infos.

However I have gone and look for prices. I say that the cheapest second-hand
chromatographer is sold for about 5000 $.
All other second hand equipment range from 10000 to 20000 $. New equipment
goes as high as 60000 $.

These costs are miles out of my budget.

I just need to be able to screen ONE sample of 24-hours urine in a small
laboratory not more than once a day for research purposes.

Is HPLC the ONLY method to do that ?? Is it not possible to take three
separate measurements with three different samples for each Dopamine,
Norepinephrine and Epinephrine by using other kind of detectors ??

High performance is not needed. We have plenty of time and patience.
We just don't have money.
We are medical informatics, and unpaid 'free researchers' in the field of
physiology.

Thanks for your help.

John.