coulometric detection

[MR V VUMA]

This is for netters who have experience with ESA electrochemical detectors.

I'm developing a bioanalytical method for a catecholamine-like drug and am 
using an ESA 5100 electrochemical detector with a 5010 analytical cell plus 
a guard cell attached to a LC with a C18 column(M/Phase is phosphate 
buffer/methanol with 100mg/l of Heptane sulphonic acid). Recently I have 
been having problems of getting a steady baseline...I've tried to find the 
source of this but have failed thus far. Initially I thought that my LC pump 
had developed some major pulsing but the pattern is so irregular I have 
discounted it as a cause.

Has anyone experienced similar problems and how did they solve them? Is ESA 
online and if so what is their email address??


Any help/comments gratefully accepted...


Vusi Vuma
Biopharmaceutics Research Institute
Rhodes University
Grahamstown
South Africa