Separation/Preconcentration System Based on Emulsion-Induced Breaking Procedure for Determination of Cadmium in Edible Oil Samples by Flow Injection-Flame Atomic Absorption Spectrometry

Abstract

In this work, a new procedure using extraction induced by emulsion breaking (EIEB) procedure has been developed for extraction/preconcentration of cadmium in various edible oils (canola, corn, hazelnut, olive, and sunflower oil) prior to its determination by flow injection (FI) flame atomic absorption spectrometry (FAAS). Five chemical variables (surfactant type, concentration of the surfactant, concentration of the nitric acid, emulsion breaking time, and temperature) were selected as the main factors affecting extraction efficiency, and two variables (sample flow rate and sample volume) were studied for optimizing flow injection conditions. The limits of detection of 1.53 and 1.55 μg L−1 were observed for cadmium when aqueous standard and oil-based standards were added to the samples for calibration, respectively. The linear range of cadmium in aqueous standard was varied in the range of 5.9–94 μg L−1. The precision of the EIEB procedure was obtained as 4.1 % by determination of ten replicates of 2.5 μg L−1 of cadmium, and the preconcentration factor 13.8 was obtained from only 4 mL of edible oil samples. The accuracy of the procedure was performed by comparison with the reference method based on the digestion of samples in a closed-vessel microwave oven and by spiking the samples with the known amounts of the cadmium in the form of oil-based standards. There were no statistical differences between the results obtained with the EIEB procedure and the reference microwave digestion method, and the recoveries were in the range of 97–104 %.