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

摘要

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 microwaveinduced 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 1 253.7-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 PSP,Hg could be determined by applying the flow injection cold vapor (FI-CV)technique with a detection limit of 50pg.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 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.