Analysis of PbBi eutectic after matrix separation by acid induced dispersive liquid–liquid microextraction followed by HR-CS-ETAAS determination

Abstract

A simple acid-induced surfactant assisted dispersive liquid–liquid microextraction procedure, AI-SA-DLLME, is delineated to detect trace impurities in lead–bismuth eutectic, LBE, using ETAAS after simultaneous separation of the major matrix elements such as lead and bismuth. In this process, matrix elements form reactive anionic iodide species, PbI₄²⁻ and BiI₄⁻ in the presence of mixed mineral acids and iodide. These species simultaneously react with cationic head groups of cetyl trimethyl ammonium bromide (CTAB) hydrophilic dispersing micelles and form extractable hydrophobic ion-associates, PbI₄²⁻-(CTAB)₂ and BiI₄⁻-CTAB. These ion associates are extracted from the bulk aqueous phase into a small micelle rich organic phase in the presence of sulphuric acid using chloroform. The extraction efficiency of lead and bismuth is found to be more than 99.4%. The trace impurities such as As, Be, Cd, Cr, Cu, Fe, Mn, Ni, Sb, Te and Tl in the aqueous phase are determined using ETAAS. The parameters affecting the process are optimized. Under the optimized conditions, the spike recoveries of impurities are found to be between 90 and 104%, and relative standard deviations within and between the processes are between 2% and 10%; and 6% and 15%, respectively. The accuracy of the procedure is verified by comparing the values obtained from ETAAS with those of ICP-OES. The good agreement between values indicates the validity of the procedures. The limits of detection obtained for Cd, Cr, Cu, Fe, Ni, As, Be, Mn, Sb, Te and Tl are 3, 120, 300, 360, 40, 30, 1, 2, 80, 90 and 40 ng g⁻¹ respectively. This procedure is applied to real Pb–Bi eutectic matrices.