Determination of Elemental Constituents in Different Matrix Materials and Flow Injection Studies by the Electrolyte Cathode Glow Discharge Technique with a New Design

摘要

An open-to-air type electrolyte cathode discharge (ELCAD) has been developed with a new design. The present configuration leads to a stable plasma even at low flow rates (0.96 mL/min). Plasma fluctuations arising from the variations in the gap between solid anode and liquid cathode were eliminated by providing a V-groove to the liquid glass-capillary. Cathode (ground) connection is given to the solution at the V-groove itself. Interfaced to atomic emission spectrometry (AES), its analytical performance is evaluated. The optimized molarity of the solution is 0.2 M. The analytical response curves for Ca, Cu, Cd, Pb, Hg, Fe, and Zn demonstrated good linearity. The limit of detections of Ca, Cu, Cd, Pb, Hg, Fe, and Zn are determined to be 17, 11, 5, 45, 15, 28, and 3 ng mL~(-1). At an integration time of 0.3 s, the relative standard deviation (RSD) values of the acid blank solutions are found to be less than 10percent for the elements Ca, Cu, Cd, Hg, Fe, and Zn and 18percent for Pb. The method is applied for the determination of the elemental constituents in different matrix materials such as tuna fish (IAEA-350), oyster tissue (NIST SRM 1566a), and coal fly ash (CFA SRM 1633b). The obtained results are in good agreement with the certified values. The accuracy is found to be between 7percent and 0.6percent for major to trace levels of constituent elements and the precision between 11percent and 0.6percent. For the injection of 100 (mu)L of 200 ng mL~(-1) mercury solution at the flow rate of 0.8 mL/min, the flow injection studies resulted in the relative standard deviation (RSD) of 8percent, concentration detection limit of 10 ng/mL, and mass detection limit of 1 ng for mercury.