Clogged ESA electrochemical cell, model 5030

[Yradak]

Hi. I was using an ESA electrochemical cell, model 5030
http://www.esainc.com/docs/spool/70-673 ... C_Cell.pdf
placed between HPLC and MS detector. The main goal was to separate the compounds by HPLC column, then modify them electrochemically in the cell and obtain MS spectra of this modified products. However, the cell seems to be clogged after running a few, approximately 30-40 analyses.
This clogging presents itself in rising backpressure after connecting the cell to system. I was trying to clean the cell with a separate pump and procedures described in manual (incl 60% H3PO4; 1M NaOH; sequential wash procedure, reversing flow), but nothing seems to work. It's even impossible to pass pure water at flow rate of 0.02 mikroL/min without getting the backpressure increased so much, that the inlet fitting is unable to hold it and starts leaking. It's a porous graphite electrode, see the link above.
Not to forget, all mobile phases are cleaned to MS-suitable purity through a 0.22 mikron filter and a Milli-Q water is used. The inlet of cell has also a replaceable filter, which i naturally always tried to replace.
Thanks for any suggestions

[Yradak]

0.02 mikroL/min = 0.02 ml/min , of course.