Diagnostic assay of carcinoembryonic antigen tumor markers using a fluorine immobilized biosensor with handmade voltammetric circuit.

The tumor marker carcinoembryonic antigen (CEA) was investigated using a graphite pencil electrode (PE) and fluorine immobilized onto a graphite pencil carbon electrode (FPE). The optimum diagnostic conditions for square wave (SW) stripping voltammetry and cyclic voltammetry were searched. The voltammograms indicated three other detection ranges of 0.4-1.6 μg/l cyclic voltammetry (PE) seven points, 0.2-1.2 μg/l SW (PE) cathodic six points, and better sensitive ranges of 0.05-0.45 μg/l SW (FPE). These were obtained within a diagnostic accumulation time of 120 s in 0.1 mol/l ammonium phosphate electrolyte solution of pH 5.0. Under optimum SW conditions, the detection limit (S/N) approached 0.08 μg/l CEA, and the relative standard deviation at 10 mg/l CEA was 0.074% in 15 measurements. The proposed method can be applied in tumor assay using cancer patient urine.