ZnS/ZnAl2S4 nanocomposite and 2-chlorobenzoyl ferrocene, were synthesized and used to construct a modified carbon paste electrode. The electrooxidation of methionine at the surface of the modified electrode was studied. Under the optimized conditions, the square wave voltammetric (SWV) peak current of methionine increased linearly with methionine concentration in the range of 5.0×10-8 to 8.0×10-4 M and detection limit of 10.0 nM was obtained for methionine. The prepared modified electrode exhibits a very good resolution between the voltammetric peaks of methionine and tryptophan which makes it suitable for the detection of methionine in the presence of tryptophan in real samples.
