The µ-PrepCell is specifically designed to optimize the yield when metabolites are electrochemically synthesized and is the cell of choice for micro preparative work. µg quantities of metabolites can be readily synthesized in a few minutes in a well defined solvent. In continuous infusion mode over several hours, mg quantities or REDOX products can be generated which can be used as reference material for MS or for structural investigation by NMR after HPLC purification.
Schematics µ-PrepCell set-up:
Direct infusion mode for synthesis with on- and off-line MS detection (A, B) and in post-column separation mode, i.e.,LC/EC/MS mode (C), typical flow rates 20 to 100 μL/min.
Electrochemical synthesis of drug metabolites using µ-PrepCell
Continuous infusion mode of Verapamil at a flow rate of 50 μL/min. MS signal recorded every 25 min. Constant yield (metabolite 1, 2 and 3) over entire sampling (synthesis) time of 3.5 hrs
Details of the applied Pulse Mode for Verapamil Oxidation. A square wave pulse was applied close to the optimal oxidation potential (E = 0.6V) of Verapamil and repeated over time. Settings from 0.4 to 0.8 V, DE of 400 V and time durations of t1 = 1990 ms and t2 = 1010 ms were used for optimal yield (conversion) and electrode surface regeneration.
The surface area of the working electrode is approximately 10 times larger than that of the ReactorCell, a significantly higher conversion rate is obtained using the µ-PrepCell. Since a voltage pulse is used rather than a constant voltage, highest electrochemical stability over extended working periods of up-to several hours is assured. This feature makes the cell well suited for use in post-column separation settings in Protein Chemistry and other “Omics” applications.
In the same vein, the µ-PrepCell is a powerful tool for the efficient reduction of disulfide bonds in proteins and peptides and is successfully used in LC/EC/MS settings.
Like the ReactorCell, the µ-PrepCell is based on a thin-layer flow cell concept, comprising of a very smooth working electrode surface over which the sample is flowing. This results in almost zero sample adsorption, unlike the use of a porous flow through cell which is prone to adsorption and carries over. The cell can be disassembled within a few seconds for easy cleaning of the working electrode and cell compartment. An additional advantage of using this cell in amperometric mode is the formation of intermediate reaction products including reactive metabolites, useful in the understanding and prediction of the metabolic-, biodegradation- or biotransformation pathway.
Open µ-PrepCell: Ti block (top) with inlet, outlet and reference electrode (middle), spacer and rectangular working electrode in PEEK body (bottom)
The cell is used with the ROXY Potentiostat or integrated in the ROXY EC or ROXY EC/LC system, respectively. The flow rate and working potential can be optimized using the Dialogue software or dedicated MS software (e.g., XCalibur).
For maximum conversion rate and wide applicability, the cell is supplied with two electrode materials, Glassy Carbon (GC) and Magic Diamond™ (conductive Diamond, MD). For electrochemical reduction (e.g., S-S bond reduction), a special semi-precious metal electrode (SPM) is available.
|Specifications μ-PrepCell™ (High Yield and Conversion Rate)
|Cell Type||Three electrode, thin-layer reactor cell (micro preparativework)
|Spacers||50 or 100 μm, stainless steel, stackable|
|Working electrode dimension||12 x 30 mm x 1 mm (WxLxH)|
|Working electrode area (wetted)||1.9 cm2|
|Cell volume||11 μL (with 50 μm spacer)|
|Working electrodes||Glassy Carbon (GC) , Magic Diamond (MD), Semi-PreciousMetal (SPM)|
|Reference electrode||HyREF (Pd/H2 electrode)|
|Wetted materials||PEEK, Titanium, silicone rubber, Glassy Carbon orconductive Diamond (WE).|
|Flow rate||Typically 20 – 100 μL/min|
|Max. pressure||25 bar (GC electrode) , 50 bar (with MD or SPM electrode)|
|Fluidic connections||1/16” o.d. PEEK tubing, with 10-32 PEEK fingertightconnections|
|Electric connections||Cell cable for use with ROXY Potentiostat|
|204.4300||μ-PrepCell kit consisting of: μ-PrepCell includingmounting brace, spacers, reference electrode (HyRef ) andworking electrodes: Glassy Carbon (GC), Magic Diamond(MD), each 1 x.
Not included special reduction electrode (SPM), part no204.5010, see below for ordering information
|204.0501||O-ring inlet block, Silicone|
|204.0503||O-ring REF electrode, Silicone|
|204.2217||Spacer 50 µm|
|204.2218||Spacer 100 µm|
|204.5007||Glassy Carbon (GC) working electrode|
|204.5010||Semi-Precious Metal (SPM) reduction electrode|
|204.5050||Magic Diamond (MD) working electrode|