Square wave voltammetry (SWV) was used to determine vitamin C
andNADHconcentrations (not shown). The SWvoltammograms clearly
showthat the plot of peak current versus vitamin C concentration is linear
for 0.07–480 μmol L−1 of vitamin C, the regression equation being
Ip(μA)=0.0632 Cvitamin C+0.9237 (r2=0.9951) while the regression
equation for NADH in the range of 0.5–700 μmol L−1 is Ip(μA) =
0.0341 + 1.7451 (r2 = 0.9919), where C is the micromolar concentration
of vitamin C or NADHand Ip is the peak current. The detection limits
were determined at 0.03 μmol L−1 for vitamin C and 0.1 μmol L−1 for
NADH according to the definition of YLOD=YB +3σ.