Intra- and interlaboratory validation of the conductimetric method for detecting the addition of metatartaric acid in grape juice.

摘要

Intra- and interlaboratory validation of the conductimetric method for detecting addition of metatartaric acid to grape juice are described. Aspects considered include: functional properties of metatartaric acid; development of the conductimetric method; previous difficulties in implementing the analysis; analytical material and standard operating procedure for determination of tartaric instability degree (TID) (TID before hydrolysis measurement, TID after metatartaric acid hydrolysis, results of the analysis); critical technical points in the standard operating procedure (evaluation of juice to be analysed, detection of an unstable juice during TID analysis, setting conductivity meter parameters, potassium hydrogen tartarate reagent, TID analysis temp., validation of hydrolysis performance); validation plan; validation results (example of results for the first juice analysed, interpretation of results, validation of the intralaboratory reproducibility of the method, uncertainty of the analysis and decision threshold); dissemination of the protocol to other laboratories using ring tests; and conclusions of the study.