A capacitively coupled microplasma in a fused silica capillary

Abstract

The plasma cell consists of two cylindrical electrodes on a fused silica capillary of 250 mm id and an optical fibre for coupling emitted light to a monochromator. 8 W of electrical power is coupled in using an ac voltage at 20 kHz and 20 kV. Impedance matching is not necessary at the relatively low frequency employed, and the low power means that the device can be operated from a battery. The plasma can be sustained with flow rates of argon or helium between 3 and 200 mL min 21 . The temperature, determined from the helium emission spectrum employing a Boltzmann plot, is approximately 12000 K. With this system it was found possible to detect mercury as vapour via atomic emission, as well as antimony and arsenic in aqueous samples via hydride generation. Also possible was the determination of CO 2 , CH 4 and ethanol vapour from the emission of C 2 at l ~385.2 nm in argon: the detection limits obtained were 90 ppb, 30 ppb and 33 ppb, respectively.

Sample Analysis with Miniaturized Plasmas

“…A similar atmospheric pressure microplasma cell also implemented on a fused silica capillary works at 20 kV and 20 kHz and does not require any ignition system or impedance matching circuit. 40 Due to the very low frequency, this plasma device should be allotted to the dielectric barrier discharges. This microplasma is created with two annular electrodes placed around the circumference of the capillary; thus, none of the electrodes is in contact with the plasma, which prevents deterioration of the electrodes and contamination of the plasma with metal sputtered from the electrode.…”

Plasma-source mass spectrometry for speciation analysis: state-of-the-art

“…The authors reported a LOD of 82 fg/s for iodine as diiodopropane detected by atomic emission [170], as well as the speciation of several organotin compounds by GC with detection limits from 0.079 to 0.190 ng/s [171]. Guchardi and Hauser [172] have recently developed a smaller 20 kHz CCP contained entirely within a 250 m i.d. fused silica capillary.…”

Microplasma-Based Detectors for Gas Chromatography: Current Status and Future Trends

“…The use of another type of CCμP as a GC detector was reported by Guchardi and Hauser (46). The construction of the microplasma is shown in Figure 2, where a fused silica capillary was used as the discharge cavity and the dielectric layer.…”