Hua "Howard" Liu <liuhua at sc.llu.edu> a écrit dans l'article
<01bc26df$9394db60$20027097 at SARA.sc.llu.edu>...
> Hello there!
> I'm trying to quantify monoamine metabolites (5-HT, 5-HTP, 5-HIAA
> and 3-OMD, DA) in human ventricular CSF. But there're huge peaks
> of unknow substances in CSF that make the HPLC system inundated.
What is the delay of elution of these peaks ?
If they appear at the begining of the chromatogram, try to prepare your own
mobile phase into which you can change the proportion of methanol in order
to better separate the peaks. A such solution could be for 1 liter of final
solution : K2HPO4: 0.1M, EDTA: 0.1mM diluted in water (0.8 liter) in which
you add 30 to 60 ml of methanol. Prepare also 0.1 liter of acetic acid 1M
+ EDTA 1mM. This solution has to be added slowly to the former one till you
reach a pH of 4.7. Adjust to 1 liter. Filter and degas.
I had this problem of hudge parasite peaks when I used high concentrations
of co-enzyme tetrahydrobiopterin associated to high concentrations of
tryptophan. The decarboxylase inhibitor NSD 1015 can also induce artefacts.
Check these points.
Good luck !
