Herein are described an instrument and a method for using the same. The instrument comprises a fluid channel fluidly connected to at least a first fluid reservoir and a second fluid reservoir; a counter electrode (CE), a reference electrode (RE), and a working electrode (WE); and a potentiostat. The CE, RE, and WE are all disposed within the fluid channel; the potentiostat is isolated from earth ground by at least one isolator and is powered by a floating power supply; and the CE, RE, and WE are each electrically connected to the potentiostat.