Highly Sensitive Electrochemical Sensor for Nitric Oxide Using the Self-Assembled Monolayer of 1,8,15,22-Tetraaminophthalocyanatocobalt(II) on Glassy Carbon Electrode

Glassy carbon (GC) electrode modified with a self-assembled monolayer (SAM) of 1,8,15,22-tetraaminophthalocyanatocobalt(II) (4 alpha-Co(II)TAPc) was used for the selective and highly sensitive determination of nitric oxide (NO). The SAM of 4 alpha-Co(II)TAPc was formed on GC electrode by spontaneous adsorption from DMF containing 1 mM 4 alpha-Co(II)TAPc. The SAM showed two pairs of well-defined redox peaks corresponding to Co-III/Co-II and (CoPc-1)-Pc-III/(CoPc-2)-Pc-III in 0.2 M phosphate buffer (PB) solution (pH 2.5). The SAM modified electrode showed excellent electrocatalytic activity towards the oxidation of nitric oxide (NO) by enhancing its oxidation current with 310 mV less positive potential shift when compared to bare GC electrode. In amperometric measurements, the current response for NO oxidation was linearly increased in the concentration range of 3 x 10(-9) to 30 x 10(-9) M with a detection limit of 1.4 x 10(-10) M (S/N = 3). The proposed method showed a better recovery for NO in human blood serum samples.