Gas Chromatographic/Mass Spectrometric Determination of 3-Methoxy-1,2-Propanediol and Cyclic Diglycerols, By-Products of Technical Glycerol, in Wine: Interlaboratory Study
Abstract:The aim of the present study was to provide the official wine control authorities with an internationally validated method for the determination of 3-methoxy-1,2-propanediol (3-MPD) and cyclic diglycerols (CycDs)—both of which are recognized as impurities of technical glycerol—in different types of wine. Because glycerol gives a sweet flavor to wine and contributes to its full-body taste, an economic incentive is to add glycerol to a wine to mask its poor quality. Furthermore, it is known that glycerol, depending on whether it is produced from triglycerides or petrochemicals, may contain considerable amounts of 3-MPD in the first case or CycDs in the second. However, because these compounds are not natural wine components, it is possible to detect glycerol added to wine illegally by determining the above-mentioned by-products. To this end, one of the published methods was adopted, modified, and tested in a collaborative study. The method is based on gas chromatographic/mass spectrometric analysis of diethyl ether extracts after salting out with potassium carbonate. The interlaboratory study for the determination of 3-MPD and CycDs in wine was performed in 11 laboratories in 4 countries. Wine samples were prepared and sent to participants as 5 blind duplicate test materials and 1 single test material. The concentrations covered ranges of 0.1–0.8 mg/L for 3-MPD and 0.5–1.5 mg/L for CycDs. The precision of the method was within the range predicted by the Horwitz equation. HORRAT values obtained for 3-MPD ranged from 0.8 to 1.7, and those obtained for CycDs ranged from 0.9 to 1.3. Average recoveries were 104 and 109%, respectively.
Document Type: Research Article
Affiliations: 1: Bundesinstitut für Risikobewertung (BfR), PO Box 1033, D-14195 Berlin, Germany. 2: Central Science Laboratory (CSL), Sand Hutton, York YO41 1LZ, United Kingdom. 3: Istituto Agrario di San Michele all'Adige, Centro Sperimentale, Laboratorio di Analisi e Ricerche, I-38010 San Michele all'Adige (Tn), Italy. 4: Eurofins Scientific Analytics, Rue Pierre Adolphe Bobierre, BP 42301, 44323 Nantes Cedex 3, France. 5: European Commission, Joint Research Centre, BEVABS Laboratory, I-21020 Ispra (Va), Italy.
Publication date: September 1, 2004
- The Journal of AOAC INTERNATIONAL publishes refereed papers and reviews in the fields of chemical, biological and toxicological analytical chemistry for the purpose of showcasing the most precise, accurate and sensitive methods for analysis of foods, food additives, supplements and contaminants, cosmetics, drugs, toxins, hazardous substances, pesticides, feeds, fertilizers and the environment available at that point in time. The scope of the Journal includes unpublished original research describing new analytical methods, techniques and applications; improved approaches to sampling, both in the field and the laboratory; better methods of preparing samples for analysis; collaborative studies substantiating the performance of a given method; statistical techniques for evaluating data. The Journal will also publish other articles of general interest to its audience, e.g., technical communications; cautionary notes; comments on techniques, apparatus, and reagents.
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