Maintenance of HPLC-ED Systems

There is no doubt that electrochemical detectors are more prone to operational diflhcul-ties than most other HPLC detectors, and it is also more difficult to take the corrective action. The close inter-relationship between the chromatograph and the detector makes fault diagnosis and correction even more difficult. A good understanding of the basic principles underlying ED is essential to a logical and hopefully successful approach to system maintenance. Nevertheless some problems associated with ED can be difficult to resolve even for the most experienced workers. 

Dirty/poor electrode contacts Eluent pH incorrect 

Reduce if possible Check voltammogram reduce to lowest value consistent with required sensitivity optimise S/N from voltammogram 

Baseline drift System unstabiiised Allow cell longer to stabilise before use replace eluent 

Sharp spikes on baseline Regular spikes can come from other equipment in the lab Use clean mains for detector - use computer isolation block Move equipment to different location -away from ovens, spectrometers, etc. 

Excessive baseline noise Grade of reagents employed Use HPLC grade reagents use better source of water re-cycle eluent investigate use of other buffer salts add 1-2 mmol L EDTA to eluent 

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