MASS-SPECTROMETRIC DETERMINATION OF CARBON AND HYDROGEN ISOTOPE RATIOS FOR HONEY AUTHENTICITY CONTROL

As the deltaC-13 values of honeys alone cannot definitely be used to prove adulteration by addition of C4 plant sugars, they have been determined in correlation to those of the protein from honey (as an internal standard), as recently recommended. For authentic samples, a mean difference of +0.1 parts-per-thousand (range +1.1 to -0.9 parts-per-thousand) was found; more negative differences indicate the addition of C4 plant sugars. As a limit for the detection of adulteration, an addition of 7% must be taken into account. Addition of C3 plant sugars (for example, beet sugar) cannot be proved by this method; however, for certain types of honey, authenticity can be confirmed by determination of the deltaD values. A new sample preparation method for deltaC-13 determination using an automated system was tested and yielded satisfactory agreement with the results of the conventional sample preparation method. This means that a greater number of samples can be measured in a short time. This advantage and the possibility of measuring other isotopic parameters in a honey sample (for example, deltaN-15 and deltaO-18) are conditions for improving the security and precision of the method.