Simple voltammetric method for the determination of β-carotene in brine and soya oil samples at mercury and glassy carbon electrodes

Abstract

β-Carotene is a naturally occurring yellow–orange pigment, which can be derived from saline micro-algae marine phytoplankton and some plant-derived natural oils. In this work, a simple method for the determination of β-carotene, involving only solvent extraction from brine (or soya oil) samples into dichloromethane, followed by addition of electrolyte and direct measurement of the differential-pulse polarogram at mercury electrodes or differential-pulse voltammograms at a glassy carbon electrode, is described, based on the extremely well-defined two-electron oxidation process that occurs in non-aqueous solvents. The method has been applied to soya oil and brine reference concentrates and to feed and effluent samples associated with the production of β-carotene via marine micro-algae. Excellent agreement with a well-established spectrophotometric method has been obtained, confirming that the simple voltammetric method should be a useful addition to the analytical methodology available for monitoring the production of β-carotene concentrates.