Indication ion square wave voltammetric determination of thiamine and ascorbic acid

Cd2+ ion was used as an electrochemical indicator to detect V-B1 or Vc using square ware voltammetry (SWV) at a mercury film-coated glassy carbon (GC) electrode. At pH = 10 NH3-NH4Cl buffer, a new cathodic peak was found at -0.360 V (vs.SCE) by addition of thiamine, and the peak current of SWV was linear with the concentration of thiamine in the range of 1 x 10(-6) to 4 x 10(-3) M. On the other hand, the SWV peak current of Cd2+ at -0.856 V linearly decreased with addition of ascorbic acid in the range of 6 x 10(-6) similar to 10(-3) M. The effects of interference, such as citric acid, DL-malic acid, and calcium panlothenate, on thiamine or ascorbic acid determination were investigated. This method was successfully applied to the determination of thiamine or in pharmaceutical preparation.