Piezoelectric screening coupled on line to capillary electrophoresis for detection and speciation of mercury

Abstract

A new methodology is proposed for automation of the monitoring of mercury in water samples. It combines a screening unit for the total amount of mercury, consisting of a piezoelectric flow sensor, with a capillary electrophoresis unit for processing the samples containing a detectable level of mercury. For positive samples, the electrophoretic method developed allowed the speciation of mercury through the formation of the corresponding cysteine complexes. Thus, inorganic mercury, methyl-mercury, diethyl-mercury, and phenyl-mercury can be quantified. A flow system connecting the screening unit to the capillary electrophoresis instrument was developed, and allowed the on-line incorporation of a pre-concentration unit in order to achieve the desired sensitivity in the electrophoretic method. The individual components of the overall set-up functioned together in a synchronised manner.