Emulsification solidified floating organic drop microextraction assisted by ultrasound for the determination of nickel, cobalt and copper in oyster and fish samples

Abstract

In the present work, solidified floating organic drop microextraction assisted by ultrasound is proposed as the preconcentration system for the determination of trace amounts of nickel, cobalt and copper by FAAS. The main parameters such as pH, concentration of TAN, extraction time, sample and organic phase volume and the nature of the organic solvent were optimized. This system has allowed the determination of nickel, cobalt and copper with a limit of detection (LOD) of 0.03, 0.04 and 0.03 μg g⁻¹ and a limit of quantification (LOQ) of 0.10, 0.13 and 0.10 μg g⁻¹. The precision is expressed as relative standard deviations (R.S.Ds) of 3.2, 2.8 and 2.6 for nickel, copper and cobalt, respectively. Accuracy was confirmed by determination of analytes in the standard reference materials, NIST SRM tomato leaves 1573a and NIST 1577 bovine liver samples, and spike tests, with recoveries ranging from 96 to 104%. The procedure was applied for nickel, cobalt and copper determination in tin oyster and fish samples.