Voltammetry is a sensitive analytical technique for elemental detection. In a voltammeter the current is measured in the system whilst the voltage is varied. Usually 3 metal electrodes are required including the reference, auxiliary and working electrodes. In polarography, a subclass of voltammetry, the working electrode used is a dropping mercury electrode (DME). The 2 main types of voltammetry are cyclic and linear sweep voltammetry.