A Microwave-Induced Plasma Based on Microstrip Technology and Its Use for the Atomic Emission Spectrometric Determination of Mercury with the Aid of the Cold-Vapor Technique

• Published in: Analytical chemistry (Washington) Vol. 72; no. 1; pp. 193 - 197
• Main Authors: Engel, Ulrich, Bilgiç, Attila M, Haase, Oliver, Voges, Edgar, Broekaert, José A. C
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.01.2000
• Subjects: Analysis; Analytical chemistry; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Chemistry; Ecotoxicology, biological effects of pollution; Electrodes; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Mercury - analysis; Methods; Microwaves; Spectrometric and optical methods; Spectrophotometry, Atomic - instrumentation; Spectrophotometry, Atomic - methods; Terrestrial environment, soil, air; Trace analysis; Electrodeless discharge; Chemical analysis; Ecotoxicology; Transition metal; Natural soil; Microminiaturization; Soil pollution; Certified reference material; Plasma sources; Optimization; Operating conditions; Environmental control; Emission spectrometry; Microwave induced plasma spectrometry; Mercury; Flow injection
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac9906476

A new low-power, small-scale 2.45 GHz microwave plasma source at atmospheric pressure for atomic emission spectrometry based on microstrip technology is described. The MicroStrip Plasma (MSP) source was produced in microstrip technology on a fused-silica wafer and designed as an element-selective detector for miniaturized analytical applications. The electrodeless microwave-induced plasma (MIP) operates at microwave input power of 10−40 W and gas flows of 50−1000 mL·min-1 of Ar. Rotational (OH) and excitation (Fe) temperatures were found to be 650 and 8000 K, respectively. Spatially resolved measurements of the Hg I 253.7-nm atomic emission line with an electronic slitless spectrograph (ESS) showed that a cylindrically symmetric plasma with a diameter of about 1 mm is obtained. With the MSP, Hg could be determined by applying the flow injection cold vapor (FI-CV) technique with a detection limit of 50 pg·ml-1. In terms of the relative standard deviation, a time stability of <1.4% for 45 replicates within 80 min can be realized at a concentration level of 10 ng·ml-1 of Hg. Hg could be determined in the leachate of a certified standard reference soil (STSD-4) obtained by treatment with aqua regia at the 930 ± 76 ng·g-1 level. Results obtained by calibration with aqueous solutions of Hg and with standard addition were found to be in good agreement with those of cold-vapor atomic absorption spectrometry.