Analytical and technical aspects of free discharge end of plasma pencil
| Autoři | |
|---|---|
| Rok publikování | 2016 |
| Druh | Další prezentace na konferencích |
| Fakulta / Pracoviště MU | |
| Citace | |
| Popis | Plasma pencil has been employed as an alternative excitation source for atomic emission spectroscopy determination of elemental contents in solutions [1, 2]. The new arrangement of the discharge tube enables to measure spectra from the free discharge end without shielding by the quartz wall. Most intensive atomic spectra can be recorded as close as possible to the ground electrode but it is also possible to record the plasma tip radiation in the range of about 0-10 mm from the ground electrode or as long as the discharge tip is formed behind the ground electrode. The pencil sustainability and stability were tested under various operating conditions. Carrier gas and plasma gas flow rates as well as forwarded power were changed and spectra of selected elements were recorded in order to yield best signal to backgroud ratio and discharge stability. It has been found that intensities of some atomic lines increase with decreasing plasma gas flow rate, increasing carrier gas flow rate and slightly with increasing forwarded power up to 180 W in continuous mode. The pulsed mode has not been tested [2]. As in our previous studies elements of first two groups of the periodic table, zinc and copper were tested. In some cases the sensitivity increased by one order of magnitude. Calibration dependences in the range of 0.1 – 10 mg × L-1 were then measured. Also matrix effects similar to those in the previous arrangement were observed. On the other hand, electronic excitation temperature from argon atomic lines, rotational temperature from OH lines and electron number density do not significantly change as a result of mixing argon with ambient air. Matrix effects by alkali salts were also observed but not eliminated under any operating conditions. Preliminary experiments rather show that the relative decrease of the analyte lines intensities in presence of an alkali salt is preserved. |
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