Development of a multichannel separation device with an electrochemical detection
for possible application in diagnostics of dopamine metabolism-related diseases
1
Martina Komendová, 2
Suhas Nawada, 3
Radovan Metelka, 2
Peter Schoenmakers, 1
Jiří Urban
1
Masaryk University, Department of Chemistry, Brno, Czech Republic
2
University of Amsterdam, Van‘t Hoff Institute for Molecular Sciences, Amsterdam, The Netherlands
3
University of Pardubice, Department of Analytical Chemistry, Pardubice, Czech Republic
Precursors and metabolites of dopamine belongs to one class of very similar compounds
and consequently it is difficult to separate them all in a one single analysis on polymer-based monolithic
stationary phases. Therefore, optimization of a surface chemistry of stationary phases is necessary to
improve selectivity of the separation. Surface chemistry of polymer-based monolithic stationary phases
can be easily controlled by either a composition of the polymerization mixture or post-polymerization
surface modification.
In this work we have used former approach to prepare four individual monolithic stationary phases
providing different retention of ten precursors and metabolites of dopamine. Zwitterion functional
monomer with various dimethacrylate crosslinkers were used to prepare stationary phases applicable in
both reversed-phase and hydrophilic interaction retention mechanisms. A composition of the mobile
phase has been optimized by means of window diagram to find one mobile phase providing separation
with the highest possible resolution of all compounds on all columns. Each column provided separation
with different elution order and one to three unresolved peak pairs. However, after combination of four
individual separation traces all ten compounds can be easily resolved.
Hence, sample has been simultaneously injected on four monolithic capillary columns into optimized
mobile phase. To allow instant detection, miniaturized electrochemical detectors made of carbon fiber as
a working electrode and a silver microwire as a reference microelectrode have been integrated at the end
of each column.
In the finalstep, we have applied the sameapproach in thedevelopment of 3D printed titanium separation
device. The four channels of the chip have been filled with prepared monolithic stationary phases and
after integration of the electrochemical detection an injection of a sample has been tested.