Electrochemical sensor for L-cysteine by using a cobalt(II)/aluminum(III) layered double hydroxide as a nanocatalyst

A voltammetric sensor is described for the determination of L-cysteine (Cys). A pencil graphite electrode (PCE) was modified with a Co(II)-Al(III) layered double hydroxide (LDH) to obtain a disposable, inexpensive and sensitive sensor for Cys. The LDH was electrochemically deposited on the PGE by chronoamperometry. The electrochemical behavior of the modified PGE was investigated by cyclic voltammetry, differential pulse voltammetry, electrochemical impedance spectroscopy, and linear sweep voltammetry. The structure and morphology of the electrodes surface were characterized by scanning electron microscopy and energy dispersive X-ray spectrometry. Experiments were conducted in optimal condition, scan rate of 10 mV. s^-1 and the oxidation peak potential 0.15 V vs. saturated calomel electrode. The sensor has a linear response in the 100 pM to 0.1 μM Cys concentration range and a 100 pM detection limit. It was used to quantify Cys in a drug sample. Graphical abstract Schematic presentation of pencil graphite electrode modification with Co-Al layered double hydroxide nanaocatalyst by chronoamperometry, and its usage as an electrochemical sensor for L-cysteine determination.