ANALYTIC VALIDATION OF ISOTOPIC ANALYSIS OF VANILLA PRODUCTS

Extraction and purification steps were statistically studied using gas chromatography coupled on-line with isotope ratio mass spectrometry ( GC-IRMS). First, the C-13 isotope deviation of vanillin was determined for 10 extracts prepared from the same vanille bean sample. The calcu lated confidence interval (0.11) with a 95% confidence level was less than the dubiousness given by the constructor (+/- 0.3 parts per thous and), so no significative discrimination occurs during this step. Seco nd, for 36 samples of vanilla beans and flavors, the C-13 isotopic dev iation was measured, on one hand, directly on the extract prepared fro m each sample, on the other hand, after liquid chromatography purifica tion. Two statistical studies were carried out. One used the NF X 0606 6 standard (comparison of paired observations). The second is based on the protocol for evaluation of an alternative quantitative method aga inst a reference method described in the NF V 03110 standard. With a 5 % error of first kind, the two statistical treatments showed that the two methods give similar results: no carbon isotopic discrimination oc curs during vanillin purification if using well defined processes and systematic controls.