A benzoylferrocene modified multi‐wall carbon nanotube paste electrode for the measurement of methionine (MET) concentration is described. MET electrochemical response characteristics of the modified electrode in a phosphate buffer solution of pH 7.0 were investigated by cyclic voltamme‐ try, square wave voltammetry, and chronoamperometry. Under optimized conditions, the square wave voltammetric peak current of MET increased linearly with MET concentration in the range of 1.0 × 10−7 to 2.0 ×10−4 mol/L. The detection limit was 58.0 nmol/L MET. The diffusion coefficient (D = 5.62 × 10−6 cm2/s) and electron transfer coefficient (α = 0.4) for MET oxidation were also deter‐ mined. The sensor was successfully applied for the measurement of MET concentration in human urine.
