Compact automated capillary electrophoresis instrument for coupling with mass spectrometry by using sheathless electrospray ionization

The low-cost set-up is based on the flexible microfluidic breadboard approach. To avoid the use of electrically driven devices at the high voltage injection end of the capillary pneumatically actuated pumps and valves are employed. It is coupled to the mass spectrometer with a sheathless electrospray obtained in an electrodeless interface configuration. This simplification is achieved by carrying out the analysis in two distinct steps, firstly the separation without the formation of an electrospray, and secondly detection in which the electrospray is created while pumping out the content of the capillary. The performance of the instrument was tested by analysing three benzalkonium ions and the four pesticides pyrifenox, pirimicarb, cyprodinil and pyrimethanil. Detection limits between 0.36 and 0.76 µM and peak reproducibilities between 5.2% and 6.6% (50 µM standards) were obtained for the latter.