Off-line measurement of carbon stable isotopes of trisaccharides, disaccharides, glucose and fructose in honey samples

Online liquid chromatography (LC) followed by isotope ratio mass spectrometry (IRMS) is a trusted technique to detect honey adulteration based on the stable carbon isotope composition (δ13C) of trisaccharides, disaccharides, glucose and fructose. However, LC-IRMS demands specialised analytical setups not commonly found in most isotope labs. Here we investigate the use of off-line LC followed by elemental analysis (EA)-IRMS as an alternative employing more commonly available instruments. Precision and accuracy were excellent for fructose and glucose (error < 0.1 mUr), but less so for disaccharides and trisaccharides, which are similar results to online LC-IRMS. Therefore, offline LC-EA-IRMS can be a viable alternative for the analysis of honey purity employing stable carbon isotopes.