An electrochemical flow-cell for permanent modification of graphite tube with palladium for mercury determination by electrothermal atomic absorption spectrometry
| Autor: | Elisabeth de Oliveira, Ruben G. M. Moreno, Jairo J. Pedrotti, Pedro Vitoriano de Oliveira |
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| Rok vydání: | 2002 |
| Předmět: |
Auxiliary electrode
Working electrode Chemistry Analytical chemistry chemistry.chemical_element Peristaltic pump Reference electrode Atomic and Molecular Physics and Optics Analytical Chemistry law.invention law Graphite Cold vapour atomic fluorescence spectroscopy Atomic absorption spectroscopy Instrumentation Spectroscopy Palladium |
| Zdroj: | Spectrochimica Acta Part B: Atomic Spectroscopy. 57:769-778 |
| ISSN: | 0584-8547 |
| Popis: | An electrochemical procedure for palladium deposition on the inner surface of pyrolytic graphite-coated tubes for permanent chemical modification and a cold vapor generation system for the pre-concentration and determination of mercury trace levels in rain, potable, and non-potable water and lake sediment by electrothermal atomic absorption spectrometry is proposed. A tubular electrochemical flow-cell was assembled on the original geometry of the graphite tube, which operated as the working electrode. A stainless steel tube, positioned downstream from the working electrode, was used as the auxiliary electrode. The applied potential was measured against a micro Ag/AgCl (sat) reference electrode inserted in the auxiliary electrode. Palladium solution in acetate buffer (100 mmol l −1 , pH=4.8), flowing at 0.5 ml min −1 for 60 min was used to perform the electrodeposition. A homemade cold vapor generation system composed of a peristaltic pump, an injector–commutator, a flow meter and a disposable polyethylene gas–liquid separator flask (approx. 4.0 ml volume) were used. Volumes of 1.0 ml of reagent (2.0% w/v NaBH 4 in 0.10 mol l −1 of NaOH) and 1.0 ml of reference or sample solution in 0.25 mol l −1 of HNO 3 were carried to the gas–liquid separator using the peristaltic pump. The mercury vapor was carried out to the modified graphite tube by argon flow (200 ml min −1 ), and pre-concentrated for 120 s. The characteristic mass for 1.0 ml of reference solution was 26 pg (R.S.D.=0.12%, n =5). The detection limit obtained was 93 pg ( n =20, 3δ). The reliability of the entire procedure was confirmed by addition and recovery tests and cold vapor atomic absorption spectrometry. |
| Databáze: | OpenAIRE |
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