Biamperometry. This method relies on recording at a small potential difference, the current intensity between two identical working electrodes, found in a solution where a reversible redox couple ([Fe.sup.3+]/[Fe.sup.2+], [I.sub.2]/[I.sup.-], Fe[(CN).sub.6.sup.3-]/ Fe[(CN).sub.6.sup.4-]) is present.
Particularly in DPP[H.sup.*]/DPPH biamperometry, antioxidants react with DPP[H.sup.*] (radical form) decreasing its concentration and generating DPPH (reduced form).
Chen et al., "Determination of ferulic acid based on L-cysteine self-assembled modified gold electrode coupling irreversible biamperometry," Chinese Journal of Analytical Chemistry, vol.
Linear LOD ([micro]g Detection method References range [mL.sup.-1]) ([micro]g mL.sup.-1]) 9.71-194.18 0.19 SWSV (a)  0.097-15.53 0.023 IPM (b)  0.18-582.54 0.06 DPV  0.04-2.14 7.77 x [10.sup.-3] CSV (c)  0.50-20.0 0.04 HPLC-DAD-ESI/MS (d)  0.05-5.0 0.01 CZE (amperometric) (e)  0.10-9.71 0.04 DPV  0.02-10.27 8.58 x [10.sup.-3] DPV Present (a) Square wave stripping voltammetry; (b) irreversible biamperometry; (c) cathodic stripping voltammetry; (d) high-performance liquid chromatography coupled with diode array detection and electrospray ionization mass spectrometry; (e) capillary zone electrophoresis.
Among different methods for measurement of vitamin C, such as electrophoresis , chromatography , voltammetry , biamperometry
, spectrophotometry , high-performance liquid chromatography  and titration by iodine , the simple redox titration of AA by 2,6-dichlorophenolindophenol (DCPIP) is accepted as a standard method for determination of vitamin C [9, 10].