Influence of analyzed solutions on the plasma pencil discharge
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| Year of publication | 2012 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | Herein we show an influence of analyzed water solutions containing elements in acid matrices on both the discharge physical characteristics and the excitation capabilities. It is well known that the presence of acids in solutions depresses measured lines intensities. Acids viscosity can worsen the nebulisation efficiency and the presence of acids in the discharge together with abundant water consume a non-negligible amount of the delivered electrical energy. These phenomena result in a decrease of the intensities of measured atomic emission lines of elements in the introduced solution. The determination of the elements in acid matrices is less sensitive than in pure water solutions. This behaviour is also recognizable in case of the presented plasma pencil. Experiments were realized with three single element containing solutions. The selected elements were Cu, Mg and Zn in the concentration range of 1 – 100 mg l-1 and the contents of 70% nitric acid of 2, 10, 20 and 50 ml per 100 ml flask. A decrease of the slopes of the calibration lines depends on the particular spectral line and ranges from about 10 to 20 % for the acid concentration change from 2 to 20 ml per 100 ml flask. These results are supported by changes in the rotational temperature calculated from OH radicals, excitation temperature from a set of Ar lines and electron number density from the Stark effect on hydrogen H beta line. Despite the sensitivity decrease the discharge stability was not very influenced by the presence of the acid which is in contrast to the influence of the pure water. It was also proven that the plasma pencil is capable of reliable determination of zinc content in a commercial multivitamin tab in presence of other matrix substances. |
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