Determination of toxic and other trace elements in calcium-rich materials using cloud point extraction and inductively coupled plasma emission spectrometry

A cloud point extraction (CPE) procedure for the simultaneous separation and preconcentration of Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn from materials rich in calcium prior to trace element analysis by inductively coupled plasma optical emission spectrometry (ICP OES) was developed. The method is based on the formation of hydrophobic complexes of the metal ions with PAN or 5-Br-PADAP, followed by their extraction into a surfactant-rich phase using Triton X-114 as the surfactant. The main variables affecting the extraction process, such as pH, concentration of surfactant and chelating agent were optimised. Under the optimum conditions the obtained limits of detection for Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn were of 4.0, 4.3, 2.1, 1.9, 0.3, 5.6, 40 and 2.0 μg L−1, respectively. The RSD values for 10 replicates were from 1.5% for Mn to 11% for Pb. The accuracy of the procedure was verified by analysis of certified reference material NIST 1400 (Bone Ash) and by recovery tests. The optimised method was successfully applied for the simultaneous determination of trace elements in dolomites used by different fertiliser factories.