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

Abstract

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 10% for the elements Ca, Cu, Cd, Hg, Fe, and Zn and 18% 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 7% and 0.6% for major to trace levels of constituent elements and the precision between 11% and 0.6%. For the injection of 100 microL 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 8%, concentration detection limit of 10 ng/mL, and mass detection limit of 1 ng for mercury.

On the coupling of hydride generation with atmospheric pressure glow discharge in contact with the flowing liquid cathode for the determination of arsenic, antimony and selenium with optical emission spectrometry

“…They sheared a considerable interest and are the subject of a growing number of works [1][2][3]. Among developed and studied in recent years miniaturized excitation sources there are dielectric barrier discharge (DBD), electrolyte as cathode glow discharge (ELCAD), liquid sampling atmospheric pressure glow discharge (LS-APGD), solution cathode glow discharge (SCGD), capacitively coupled plasma (CCP) and microstrip plasma (MSP) [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. In general, these new excitation sources enable efficient excitation of elements with relatively low excitation potentials, i.e., alkali and alkaline earth elements and some of transition metals.…”

“…In general, these new excitation sources enable efficient excitation of elements with relatively low excitation potentials, i.e., alkali and alkaline earth elements and some of transition metals. Limits of detection (LODs) of elements usually vary from several to tens micro gram per liter and because of that miniaturized excitation sources are commonly used for their quantification in different samples [4][5][6][7][8][9][10][11][12][13][14][15][16]. On the other hand, mentioned radiation sources are rarely utilized for the determination of elements with high excitation potentials, e.g., As, Sb or Se, with OES.…”

Coupling of cold vapor generation with an atmospheric pressure glow microdischarge sustained between a miniature flow helium jet and a flowing liquid cathode for the determination of mercury by optical emission spectrometry

“…[7][8][9][10] The values of DLs of alkaline earth metals and transition metals are higher and usually span the range of 1-25 mg L À1 . [7][8][9][10][11][12][13][14] Considering the achievements made in the last 3 years in the application of APGD generated in contact with the liquid cathode as an efficient excitation source for analytical OES, it is evident that much effort has been devoted to improving the DL of Hg. This element is usually present in food and water samples at very low concentrations.…”

The improvement of the analytical performance of direct current atmospheric pressure glow discharge generated in contact with the small-sized liquid cathode after the addition of non-ionic surfactants to electrolyte solutions

“…Changes in the design of electrolyte solution delivery capillaries made in last several years led to the improvement of the optical thinness of the discharge and its stability [4,[10][11][12][13][16][17][18][19][20][21]. A better reproducibility of the discharge gap results in a much better analytical performance of such modified discharge systems.…”

“…Linearity ranges reported for these systems typically vary from 2 to at least 4 orders of the concentration, while the precision in most cases is better than 6%. All these improved figures of merit make dc-APGD generated in contact with the liquid cathode a highly desirable instrumental method for the spectrochemical analysis of food samples, including tap, drinking and mineral waters [4,7], tea infusion [4], tea leaves [4], fresh milk [7], tuna fish [20][21][22], oyster tissue [20] or aquatic plant [22].…”