Flexcell™
Electrochemical reactor cell for µ-bore LC

• Electrochemical derivatisation
• Down to 1 µl cell volume
• Easy change of working electrodes

Electrochemical derivatisation for ECD
The DECADE II with dual cell control (DCC) can be equipped with an additional flow cell, such as a reactor cell for µ-bore LC-EC. The Flexcell is positioned between the chromatographic column and the detection flow cell. A potential is applied that converts the analyte of interest into an electroactive species that can be detected by the detection flow cell.
This approach is usually applied to obtain a better selectivity or sensitivity, and is only applicable for analytes with reversible electrochemical reaction properties. An example is the pre-reduction followed by oxidative detection of vitamin K (Antec Leyden's application note 218-005).

Fig. 1. Vitamin K. A post column Flexcell is used at -500 mV for reductive conversion of the hydroxyquinone moiety, followed by oxidative amperometric detection in a second flow cell at +300 mV (vs Ag/AgCl).

Read more: about the Flexcell the most versatile flow cell for LC-EC.

Electrochemical derivatisation for MS
Already in the early nineties reports appeared describing the use of HPLC in combination with electrochemical detection and mass spectrometry [1]. More recently a combination of LC-EC-MS was used for determination of ferrocene-labelled alcohols and phenols [2]. After LC separation the derivatives were oxidised and the charged ferrocinium products were detected using thermospray MS.
In another publication the electrochemical cleavage of peptides has been described [3]. In this method cleavage is specifically for tyrosine and tryptophan which makes the method an inter-esting alternative to enzymatic digestion.
Requirements for low flow rate in LC-MS make the Flexcell particularly suitable for µ-bore LC-EC-MS.

Fig. 3. Electrochemical reactor on-line with thermospray MS.

Flexcell
The thin-layer Flexcell with an internal cell volume of about 1 µL is particularly suitable for electrochemical derivatisations in series with other detectors. Because the efficiency of electrochemical conversion increases with lower flow rates, this cell is particularly useful in combination with µ-bore LC.
Another major advantage is that the cell can easily be serviced and change of working electrodes is possible within a minute.

References
1. H.D. Dewald, S.A. Worst ,J.A. Butcher, E.F. Saulinskas, Electroanalysis 3 (1991) 777
2. G. Diehl, A.Liesener, U. Karst, Analyst 126 (2001) 288
3. H.P. Permentier, J.U. Jurva, M.B. Barroso, R. Bischoff, A.P. Bruins, in: Proceedings of the 50th ASMS Conference on Mass Spectrometry and Allied Topics, 2002, poster TPA 002

Ordering information
The Flexcell is available with glassy carbon (GC), gold (Au), platinum (Pt), copper (Cu) or silver (Ag) as working electrode materials. 

The working electrode discs are also separately available: