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.