Miniaturized voltammetric cell for cathodic voltammetry making use of an agar membrane

Analysis of samples available in small volumes is an important challenge in analytical chemistry. Therefore, we have dealt with the development of a new miniaturized micro-volume voltammetric cell (MVVC) for the determination of reducible organic compounds in micro-volumes (20–50 μL). The MVVC is composed of two compartments, a micro-volume compartment, where the analyte is present along with the working electrode, separated by means of an agar membrane (about 2 mm) from a large-volume compartment containing the supporting electrolyte and the counter and reference electrodes. This MVVC was tested by the determination of sodium anthraquione-2-sulfonate as a model substance for structurally similar anthraquinone-based anti-cancer drugs. Using differential pulse voltammetry at a polished silver solid amalgam electrode, the following analytical parameters were obtained: linear dynamic range from 1 μmol L^{− 1} to 1 mmol L^{− 1}, repeatability of 0.7% (on the concentration level 0.1 mmol L^{− 1}), and limit of detection of 0.15 μmol L^{− 1}.