Detection of adulteration of commercial honey samples by the 13C/12C isotopic ratio

It is very difficult to detect adulteration by conventional laboratory methods. However, differences in stable carbon isotope ratio (13C/12C=‰), between honey and its protein fraction give a qualitative and quantitative indication of honey adulteration. Forty honey samples from Brazil and eight imported from Argentina, Canada and the USA, were analyzed to detect possible adulteration by gas chromatography/mass spectrometry. Honey was adulterated with sucrose solution and high fructose corn syrup (HFCS) to determine detection limits. The 13C/12C value for honey and its protein fraction should not differ more than 1‰ for delta (δ). The range of values found for bee-produced honey was −21.96‰ to −30.47‰ for C3 plants and −11.82‰ to −19.00‰ for C4 plants (produced near cut sugar cane and not considered to be flower honey). For cane sugar it was −11.33‰ to −11.78‰, and −9.70‰ to −9.78‰ for HFCS. Adulteration was found in six Brazilian honey samples.