Vitamin stripping voltammetry

Besides trace metals, adsorptive stripping voltammetry has been shown to be highly suitable for measuring organic compounds (including cardiac or anticancer drugs, nucleic acids, vitamins, and pesticides) that exhibit surface-active properties. 

Recent studies describe the use of cyclic voltammetry in conjunction with controlled-potential coulometry to study the oxidative reaction mechanisms of benzofuran derivatives [115] and bamipine hydrochloride [116]. The use of fast-scan cyclic voltammetry and linear sweep voltammetry to study the reduction kinetic and thermodynamic parameters of cefazolin and cefmetazole has also been described [117]. Determinations of vitamins have been studied with voltammetric techniques, such as differential pulse voltammetry for vitamin D3 with a rotating glassy carbon electrode [118,119], and cyclic voltammetry and square-wave adsorptive stripping voltammetry for vitamin K3 (menadione) [120]. 

Folic acid is part of the vitamin B complex, and its electrochemical and biological reduction schemes have been reported by Dryhurst. Its fully reduced form, tetrahydrofolic acid, is important because it acts as a carrier for a formate unit. Thus, formyl-N -tetrahydrofolic acid is involved in the biosynthesis of nucleic acid, primary constituents of living cells. Alternating current adsorptive stripping voltammetry has been applied to the determination of (I) in human seru. ... 

Electrochemical methods of analysis are extremely sensitive and have been exploited to permit the detection of a wide range of analytical targets down to concentrations of the order 10 M in favorable conditions. The relative low cost of these electroanalytical techniques when compared with conventional techniques such as Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and Atomic Absorption Spectroscopy (AAS) has led to the use of electrochemical stripping voltammetry (Chapter 2.3) and linear sweep voltammetry (Chapter 2.1) for the detection of both inorganic and organic species [1-6]. Target analytes that have been documented include heavy metals (Bi, Cu, Cd, Ga, Mn, Pb, Sb, Sn, V, Zn), cardiac and anticancer drugs, vitamins, and pesticides. However, the limits of applicability for these silent classical electrochemical techniques have been compromised by four main drawbacks ... 

Fig. 65. Comparison of three voltammetric stripping responses under equal accumulation conditions. (A) linear sweep voltammetry, (B) differential pulse voltmametry, (C) square-wave technique. Conditions 5 x 10 M vitamin K3 in 0.3 M HCIO3, static MDE, accumulation potential, Eacc=-0.1V (vs. Ag/AgCl), tacc = 60s, rest time tr=10s. Linear sweep rate v = 0.02Vs , differential pulse scanning 0.01 Vs , SW-scanning 0.20Vs pulse amplitudes dEop = JEsw = 0.02 V, SW frequency 100 Hz. Adapted according to [162].

---