Development of a dispersive micro-solid phase extraction method based on using cobalamin as a green adsorbent for the extraction of Cd(II) and Pb(II) from oil samples

Abstract

ABSTRACT A dispersive micro-solid phase extraction procedure using cobalamin as a green sorbent has been developed for the extraction of Cd(II) and Pb(II) ions from oil samples. At first, a desired amount of oil sample was dissolved in chloroform. Then, the specified amount of cobalamin was added and vortexed. After centrifuging, the separated solid particles were dissolved in nitric acid solution. Finally, the analytes were analysed by flame atomic absorption spectrometry. Effects of different analytical parameters such as amounts of sample and cobalamin, vortex time, complexing agent amount, type and volume of dissolving solvent, and temperature on the extraction efficiency of Pb(II) and Cd(II) ions were investigated and optimised. Under optimised conditions, calibration curves were established with the linear ranges of 1.5–150 μg Kg−1 for Cd(II) and 1–150 μg Kg−1 for Pb(II). The detection limits were found to be 0.48 and 0.34 µg Kg−1 along with extraction recoveries of 89.1% and 94.8% for Cd(II) and Pb(II) ions, respectively. The proposed method demonstrated good repeatability, with the relative standard deviation ranging from 3.8% to 4.1% (n = 6, C = 10 μg Kg−1 of each cation). Finally, the method was successfully applied to determine the concentrations of Cd(II) and Pb(II) ions in various oil samples.