Exploiting Sequential Injection on-line Solvent Extraction/Back Extraction with Detection by ETAAS or ICPMS

Electrothermal atomic absorption spectrometry (ETAAS) and inductively coupled plasma mass spectrometry (ICPMS) are highly sensitive techniques for trace metal analyses. Nevertheless, separation/preconcentration procedures are often called for in order to overcome their inherent low matrix tolerances. With detection by ETAAS, separation/preconcentration by solvent extraction has enjoyed much use. However, this approach is not necessarily the optimal one since introduction of organic eluates directly into the graphite tube might lead to deteriorated reproducibility and lower sensitivity. And for ICPMS, organics are prohibitive because they give rise to an unstable plasma, and excessive carbon deposited on the sampling and skimmer cones might result in a gradual loss of sensitivity. All of these difficulties can be readily overcome by using solvent extraction/back extraction. Surprisingly, this approach has not been much used, probably because it is laborious and intricate to implement. However, automated in a sequential injection system, it is unproblematic to operate and effectively eliminates sample contamination, thereby presenting itself as a most attractive on-line procedure This poster presents an on-line SI-solvent extraction/back extraction procedure used in connection with detection by either ETAAS or ICPMS. Incorporating two newly designed dual-conical gravitational phase separators, its performance is demonstrated for the determination of various metals in reference materials.