Sensitive determination of paracetamol using a graphene-modified carbon- paste electrode

The electrochemical behavior of paracetamol was investigated at a graphene - modified carbon paste electrode by cyclic voltammetry in an ammonium buffer solution (pH 8.5). The modified electrode showed excellent electrocatalytic activity towards the oxidation and reduction of paracetamol resulting in a remarkable lowering of the peak potentials and considerable improvement of the peak currents as compared to the bare electrode. Despite the irreversible behavior at the surface of a carbon paste electrode, a quasi-reversible redox process at the graphene modified electrode was observed for paracetamol with a peak separation of 66 mV at a scan rate of 50 mV s(-1). The advantages are related to the unique properties of graphene such as large surface area, and increased electron transfer abilities compared to graphite. Square wave voltammetry was applied to the quantitative determination of paracetamol using the graphene modified carbon paste electrode after an accumulation time of 2 min. The calibration graph was linear in the concentration range of paracetamol of 2.5 to 143 mu M with a sensitivity of 0.282 mu A/mu M and the detection limit was about 0.6 mu M (S/N=3). The method was used in the determination of paracetamol in pharmaceutical preparations and urine samples successfully.