Optimization and validation of a microwave digestion method for multi-element characterization of Romanian wines

An analytical method for determination of multi-element composition of Romanian wines using microwave digestion for sample preparation and ICP-MS (inductively coupled plasma mass spectrometry) was optimized and validated. Best recoveries, ranging from 85.63 % to 119.08 were analyzed elements, using a volume of 0.5 mL wine, 7 mL HNO3 and 1 mL H2O2. In total 35 elements (Ag, Al, As, B, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Ga, Ge, In, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, S, Sb, Se, Si, Sn, Sr, Te, Ti, Tl, V and Zn) were determined in the wine samples. A total of 156 wine samples (96 white wines, 54 red wines and 6 rose wines) were analyzed in this work. All wines used in this study were form the 2011 vintage and were collected directly from the Romanian wineries in 750 mL glass bottles. The calibration curves of all elements were linear with correlation coefficients (R2 ) ranging from 0.9991 for Cd to 0.9999 Al, As, Ba, Be, Ca, Co, Fe, Ga, Li, Mg, Mo, Na, P, 208Pb, Sb, Se, Sn, Te, Ti and Zn. The accuracy of the method was checked with a standard addition method showing good repeatability and reproducibility (relative standard deviation, RSD<10%). In this study the characterization of Romanian wines according to their elemental composition was performed. Potassium, magnesium and calcium were the most abundant elements in all investigated wine samples. Concentration of Na (1 mg/L), Cu (1 mg/L), As (0.2 mg/L), Cd (0.01 mg/L), Zn (5 mg/L) and Pb (0.15 mg/L) metals in analyzed wine samples were under the maximum permissible limits (MPL)