engleski

Preparation of wine for the analysis by analytical techniques: NMR, IRMS and ICP-OES– method validation

Stable isotopes and mineral composition of wines have been recognized as indicators of wine's authenticity, and methods for their determination have been developed. Stable isotope ratios of (D/H)I and (D/H)II of wine is determined by the SNIF-NMR® (Site Specific Natural Isotope Fractionation - Nuclear Magnetic Resonance) for the methyl- and the methylene-position of the ethanol molecule. The determination of 13C/12C is performed in the ethanol molecule by the IRMS - Isotope Ratio Mass Spectrometry. For both methods, ethanol from the wine is obtained using ADCS - Automated Distillation Control System. The residue after distillation is ethanol free and therefore suitable for determining the macro- and microelements by the ICP-OES (Inductively Coupled Plasma – Optical Emission Spectrometry) method. The aim of this paper was to validate the wine sample preparation by ADCS in order to obtain a distillate with an alcohol grade of 92-93% w/w. Repeatability of the method was determined by distillation of the same sample on four distillation columns in six replicates. Obtained mean value was 92.60 ± 0.23% w/w. The relative standard deviations (RSD) were calculated for each column and they were: 0.15, 0.13, 0.31, and 0.12%, respectively. Determination of the distillate water content was performed by KarlFischer titration method and the repeatability of water determination was calculated (RSD = 0.25%). It was concluded that the method is fit for the intended purpose, which is preparation of the wine sample for analysis by analytical techniques: NMR, IRMS and ICP-OES.

authenticity ; validation method of distillation ; wine

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