ACH - Models in Chemistry 136. (1999)

1–2. szám - 40TH HUNGARIAN CONFERENCE ON SPECTROCHEMISTRY - Czövek, Z.–Gáspár, A.–Braun, M.–Posta, J.: Atomic spectrometric determination of vanadium in oils using different sample pretreatment methods

96 CZÖVEK et al.: Atomic spectrometric determination of vanadium in oils The different digestion procedures of oils and liquids of great viscosity should preceede the atomic spectrometric analysis. In this work two conventional digestion technics and a new burning method in bomb calorimeter [4] were applied and compared. Experimental Apparatus The multielement (Na, K, Sr, V, Cr, Fe, Cu, C, S) determinations of solutions obtained by using different digesting procedures were carried out by a Spectroflame type inductively coupled plasma atomic emission spectrometer (ICP/AES) (Spectro) under conditions suggested by the manufacturer. An atomic absorption spectrometer model Varian SpectrAA-10 equipped with a deuterium lamp background corrector was used for the flame atomic absorption measurements of vanadium. The hollow cathode lamp was operated with a current of 12 mA. The wavelength of the measurement line was 318.5 nm, the band width of the slit 0.2 nm, the observation height was 8 mm. Fuel rich nitrous oxide/acetylene flame (nitrous oxide: 3.8 units, acetylene: 5.0 units) was used. For the reverse phased (RP) high pressure liquid chromatographic (HPLC) separation of Viv/Vv a high-pressure pump model Knauer HPLC PUMP 64, a Knauer injector with a 500 pi loop and a C18 column made by Knauer (silica-based, 50x4.6 mm Eurospher 100-C18 with a particle size of 5 pm) were used. The ashing of the samples was carried out in a furnace (Elekthermax) that can be heated up to 1000 °C. The wet digestion of the samples were carried out in MILESTONE MLS-1200 MEGA microwave digester. For burning oil samples the Berthelot-Mahler bomb calorimeter was modified in a suitable way. Reagents Reagent grade chemicals were used. Vanadium) V) stock solution (1 mg /ml) was prepared by dissolving 2.298 g of ammonium metavanadate (Reanal) in 1 litre of distilled water heated to 80 °C. Vanadium(IV) stock solution (1 mg/ml) was prepared by dissolving 4.96 g of VOSO^^O (REANAL) in 1 litre of distilled water. The 1: 1 HC1 used for dissolving residues obtained by ashing, the 65 % (mlm) nitric acid and the 30 %(m/m) hydrogen peroxide for microwave digestion and the 1 M nitric acid for dissolving residues obtained by burning in bomb calorimeter were Reanal products. * С и - models in Chemistry 136, 1999

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