Voltammetric determination of nicotinic acid by glassy-carbon electrode modified with multiwall carbon nanotubes

A glassy-carbon electrode modified with a thin film of multiwall carbon nanotubes is used for the determination of nicotinic acid (NA). At the electrode, the latter yields a well-defined and very sensitive oxidation peak at 0.21 V (SCE). Investigation of the electrochemical behavior of NA shows that the electrode significantly enhances the NA oxidation peak current, compared with the non-modified electrode. Based on this, a very sensitive and simple electrochemical method is proposed for the NA determination after the optimization of all experimental parameters. The oxidation peak current is proportional to the NA concentration over the range 2 x 10(-7) to 4 x 10(-5) M, and the detection limit is 8 x 10(-8) M after a 4-min accumulation. The relative standard deviation of 5.4% for the successive determination of I X 10(-6) M NA (n = 10) indicates excellent reproducibility. The analysis method is successfully demonstrated using tablet samples.