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Apple juice is one of the world’s most widely consumed fruit juices and is therefore a common target for economically motivated adulteration (EMA). Such adulteration may involve dilution with water, substitution with other juices, or the addition of exogenous sugars, each requiring robust analytical methods for detection. In this study, we present an improved analytical method for identifying exogenous C4-type sugars in apple juice which utilizes the naturally occurring sorbitol as an endogenous isotopic reference marker. The method uses liquid chromatography coupled to isotope ratio mass spectrometry (LC-IRMS) to determine the δ13C values of the major endogenous sugars in apple juice. The study shows that the δ13C value of sorbitol can be measured in the same analytical run as the other major sugar components and remains unaffected by the addition of exogenous C4-type sugars to the apple juice. This method offers significant advantages over existing approaches, notably by eliminating the need for extensive sample preparation and multiple analytical methods thereby improving both analytical throughput and ease of use.
Seed et al. (Tue,) studied this question.