DESIGN AND SELECTIVE APPLICATION OF A DROPPING MERCURY-ELECTRODE AMPEROMETRIC DETECTOR IN COLUMN LIQUID-CHROMATOGRAPHY

The design of a polarographic detector is described and its performance is compared with that of a commercial solid-state amperometric detector using a glassy carbon electrode and with a UV detector. For the dropping mercury electrode (DME) detector, conically ground capillaries and reference electrodes are used in order to improve the dead volume and the response. The applicationof this detector to thiourea herbicides, making use of the specific complexation of these organosulphur compounds with the mercury surface, is discussed. In artificial solutions of the thioureas the performance of the DME detector is about the same as that of a UV detector but inferior to that of a solid-state detector. For urine analysis the Dme detector profits from its high inherent selectivity and the absence of surface poisoning, which makes it the detector of choice for this type of application. © 1979.