The intra-laboratory study of EIM-IRMS® (Ethanol Isotope Measurement–Isotope Ratio Mass Spectrometry) method performance with CS-qNMR (Cumulative Screening–quantitative NMR)

Abstract

In our earlier publications we proposed the possibility of using new EIM–IRMS® instrumental technique and analytical parameter δDn wine ethanol, which represents δ2H value of non-exchangeable hydrogen stable isotope ratio in ethanol, to improve detection of illegal wine production practices such as addition of sugar and/or water to grape must prior to alcoholic fermentation. This article shows a comparative performance study between EIM-IRMS® and CS-qNMR methods in order to evaluate potential and demonstrate the precision of two isotopic concepts and their degree of detection of illegal wine production practices. Three batches of laboratory wine samples were prepared from three different types of grapes (N=24 samples). Sample results obtained from both methods are compared and a statistical data processing was carried out. Based on the results obtained using the EIM-IRMS® method we detected 11 out of 21 of previously adulterated wine samples which represents a success rate of 52.4% detection of illegal practices (beet sugar, water or beet sugar syrup additions). In addition, wines from the Republic of Serbia (90 samples) were examined as well using the EIM-IRMS® method and appropriate equipment to confirm their authenticity.

Determining sugar and molasses origin by non‐exchangeable hydrogen stable isotope of ethanol and carbon isotope ratio mass spectrometry

“…All other samples from the sequence are corrected for this correction factor and thus placed in the same line, that is, as if they were all made in the same water matrix. In this way, the contribution from the methylene group of ethanol is blocked, and in this case, the differences in δ D n values of ethanol arise only based on differences in the relative ratio of hydrogen stable isotopes from the methyl group of ethanol, which is indicative for determining the botanical origin of ethanol and the sugar raw material from which it was derived (Smajlović et al., 2023).…”

“…For measuring isotopic ratios of carbon ( 13 C/ 12 C), the technique of mass spectrometry with a double collector was used. Isotopic ratios were measured by the simultaneous measurement of three ion beams ( 12 C 16 O 16 O + , 13 C 16 O 16 O + , and 13 C 16 O 18 O + ) and by comparing the sample to a standard (Smajlović et al., 2023). For expressing the relative difference between isotopic ratios of sample and reference gas (standard), δ 13 C is used, which is defined as $$$$\begin{equation*}{\delta ^{13}}C\;({\% _0}) = \left[ {\frac{{{R_{Sample}} - {R_{Standard}}}}{{{R_{Sample}}}}} \right]\; \times {10^3}\end{equation*}$$$$where R Standard is the absolute isotopic ratio ( 13 C/ 12 C) of an international standard for carbon, and it represents R = 0.0112372 (Rossmann, 2001).…”

“…The isotopic measurements of δ ing the sample to a standard (Smajlović et al, 2023). For expressing the relative difference between isotopic ratios of sample and reference gas (standard), δ 13 C is used, which is defined as…”

“…Additionally, the combination of δD n and δ 13 C values of ethanol allowed for the differentiation of various ethanol sources present in wine (Smajlović et al, 2013). A previously published interlaboratory study by four different laboratories showed the robustness of the EIM-IRMS method in determining the authenticity of wine (Smajlović et al, 2023). The EIM-IRMS showed more precise measurements than CS-qNMR, with a repeatability standard deviation of .17 ppm compared to 1 ppm, making it a more accurate method than its alternatives (SNIF-NMR, CS-qNMR, etc.).…”

“…Nuclear magnetic resonance (NMR)‐based methods to obtain non‐exchangeable hydrogen stable isotope information use different internal standards and require 19 F nucleus stabilization for the calculation of signal integration (Ivlev et al., 2019; Kalabin et al., 2018; Smajlović et al., 2023). Even though NMR‐based methods can be used to authenticate the botanical and geographical origin and detect adulterations in various products, they are quite expensive in terms of equipment acquisition, method application, and maintenance, consequently giving considerably high analysis costs per sample.…”