Next generation of dielectric barrier discharge hydride atomizers for atomic absorption spectrometry: A case study on Pb, Bi, Se and Te
Abstrakt
The performance of hydride atomizers based on dielectric barrier discharge (DBD) was evaluated by atomic absorption spectrometry as a detector employing Pb, Bi, Se and Te as model analytes. Two designs of DBD atomizers either with glued or sputtered electrodes were investigated in combination with sinusoidal or square-wave modulated high voltage power supply sources.
Moreover, the effect of gas phase dryers on analyte response was studied. Nafion tubes were found as universal dryers capable of efficient water vapor removal with no losses of analyte.
Sensitivity was compared among individual DBD configurations being related also to conventional externally heated quartz tube (multi)atomizers (MM)QTA. For Te and Se comparable sensitivities were reached in all configurations of DBD atomizers and MMQTA.
On the contrary, QTA provided three times higher sensitivity for Bi and Pb than DBD atomizers. Sensitivity reached among DBD atomizers was the same regardless of their electrode design and high voltage waveform modulation for Se, Te and Bi.
Differences in sensitivity were observed for Pb depending on DBD atomizer configuration. Here the best sensitivity was found in DBD with sputtered electrodes coupled to power source with square-wave modulation of high voltage.
It was twice higher than that reached in the DBD atomizer with glued electrodes powered by sine-wave voltage. The sensitivity in DBD atomizers correlates negatively with the amount of analyte deposited in the atomizer during atomization. >90% of Bi and Pb introduced into the system is deposited while the deposited fraction of Te and Se, respectively, decreases to 60% and 35%.