Simultaneous Determination of Vitamin E and Vitamin K1 Using Adsorptive Stripping Voltammetry at Glassy Carbon Electrode

Abstract

Adsorptive stripping square wave voltammetry (AdSWV) at glassy carbon electrode was (GCE) developed for simultaneous determination of vitamin E (α-TOH; α-tocopherol) and K1 (VK1; phylloquinone). Principally, vitamins mentioned are accumulated together onto freshly polished surface of GCE from an aqueous-organic mixture (50% acetonitrile) at 100 rpm for 5 min and subsequent voltammetric detection using SWV performed in 0.01 M HNO3 solution with a content of 0.1 M KCl (pH 2.08) at deposition potential -0.1 V for 60 s, equilibrium time 5 s, potential step 5 mV, potential amplitude 30 mV and frequency 80 Hz. Due to limiting surface size (diameter 3 mm) and them self-interaction, short linear calibration ranges for each fat-soluble vitamin were found, namely 1-10 μM with R2=0.9957 for α-TOH and 1-6 μM with R2=0.9966 for VK1. It seems that developed AdSWV could find its application in the food analysis, especially in quality control of edible oils and margarines.