The application of ETAAS to the determination of Cr, Pb and Cd in samples taken during different stages of the winemaking process
2002
Kristl, Janja | Veber, Marjan | Slekovec, Metka
Chromium, cadmium and lead were determined in different fractions of the winemaking process such as in grape, pressed pomace, must deposit, deposit of lees, must and wine. Grape, pressed pomace, must deposit and deposit of lees were digested by a high-pressure microwave-assisted digestion system with a mixture of nitric acid and hydrogen peroxide, while for must and wine no special treatment was required. The temperature programs of the graphite furnace were optimised and different matrix modifiers were applied: Mg(NO₃)₂, NaVO₃for Cr and NH₄H₂PO₄, Pd(NO₃)₂for Pb and Cd determinations. Mg(NO₃)₂and NaVO₃thermally stabilized Cr and enabled the increase of pyrolysis temperatures up to 1500 °C. NH₄H₂PO₄and Pd(NO₃)₂ are suitable modifiers for Pb and allowed pyrolysis temperatures up to 800 °C in grape, pressed pomace and wine samples, 1100 °C in must samples and 1200 °C in deposit of lees. The non-specific background absorption of NH₄H₂PO₄was 1.5–2 orders of magnitude higher than that of the Pd(NO₃)₂.
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