Determination of the 13C contents of organic acids and sugars in fruit juices: an inter-comparison study

The determination of the repeatability (r) and reproducibility (R) of the (13C/12C) measurement in sugars and organic acids contained in different fruit juices was conducted on an international basis involving 17 laboratories. The mean values of rper thousand (Rper thousand) for acids and sugars are, respectively, equal to 0.58 (1.75) and 0.34 (0.71) and the relatively large values observed for R of acid determinations are related to the preparation step. However, the least significant difference computed for several pairs of natural and spiked juices indicate that the 13C method can be applied for detecting fruit juice adulteration. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)