A simple electroanalytical procedure for the determination of calcium in biodiesel

An alternative method is proposed for the determination of calcium in biodiesel samples using square-wave voltammetry and a glassy carbon electrode in a solution containing EDTA. A microwave assisted acid digestion of the biodiesel samples was carried out before analysis. Experimental parameters such as deposition potential, deposition time, frequency, amplitude, step potential, were optimized for the purpose of determination of trace calcium ion in 1 x 10(4) mu mol L-1 ammonium buffer solution (pH 9.4) in the presence of 400 mu mol L-1 of EDTA. Under optimal conditions, the limit of detection was 1.6 x 10(-3) mu mol L-1 for Ca2+ with a 2 min preconcentration time. In addition, the EDTA/GCE displayed good reproducibility (CV maximum of 0.70%) and accuracy (recovery around 102%) making it suitable for the determination of Ca2+ in real biodiesel sample. (C) 2013 Elsevier Ltd. All rights reserved.