DETERMINATION OF C-13 CONTENT OF SUGARS OF FRUIT AND VEGETABLE JUICES - A EUROPEAN INTER-LABORATORY COMPARISON

An inter-laboratory comparison, organized by a working group of the technical committee for the analysis of fruit and vegetable juices of the European Commission of Standardization (CEN/TC 174), was carried out between fifteen laboratories in seven European countries on the determination of the carbon-13 content of sugars of fruit juices. Each laboratory received two randomly selected samples, each of 250 ml, of orange and pineapple juice and two samples, each of 50 g, of sucrose from beet and cane sources. The determination of carbon-13 in sugars of fruit juices was evaluated using the same experimental protocol but under different conditions (operator, spectrometer, period of time). The results obtained for this method were considered to be acceptable by specialists in the field of isotopic analysis: the repeatability (r) and reproducibility (R) obtained in the ring test were 0.3 parts per thousand and 0.7 parts per thousand, respectively, according to the ISO Standard 5725-1986.