Thermal Desorption–Vocus Enables Online Nondestructive Quantification of 2,4,6-Trichloroanisole in Cork Stoppers below the Perception Threshold

Abstract

2,4,6-Trichloroanisole (TCA) contamination of wine determines huge economic losses for the wine industry estimated to amount to several billion dollars yearly. Over 50 years of studies have determined that this problem is often caused by TCA contamination of the cork stopper, which releases TCA into the wine. The human threshold for TCA is extremely low. A wine contaminated by 1–2 ng/L TCA can be perceived as tainted. Contaminations with <0.5 ng/L TCA are commonly considered negligible and are not perceivable. The possibility of prescreening cork stoppers for TCA contamination would be an enormous advantage. Therefore, the demand for a fast, nondestructive method capable of quantifying the TCA contamination in cork stoppers is impelling. Vastly used analytical methods have so far struggled to provide a fast and reliable solution, whereas sensory analysis by trained panelists is expensive and time-consuming. Here we propose a novel approach based on chemical ionization–time-of-flight (CI-TOF) mass spectrometry employing the “Vocus” ion source and ion–molecule reactor. The technique proved capable of nondestructively quantifying TCA contamination in a single cork stopper in 3 s, with a limit of quantification below the perception threshold. A real test on the industrial scale, quantifying TCA contamination in more than 10000 cork stoppers in a few hours is presented, representing the largest data set of TCA analysis on cork stoppers within the literature and proving the possibility to apply the technique in an industrial environment. The correlation with standard methods for releasable TCA quantification is also discussed.

Uncorking Haloanisoles in Wine

“…However, the authors specify that this method, in principle, would be able to detect other haloanisoles and halophenols. This method uses whole corks, does not destroy the cork, and is incredibly fast at 3 s per cork [ 47 ].…”

Electron ionization induced fragmentation pathways of trichloroanisole

“…3,13 A novel method was recently reported for the online detection of TCA based on chemical ionization mass spectrometry (CI-MS) without the need to use chromatography. 23 Peres et al 24 suggested an analysis through cyclic voltammetry (CV) which yields good results when compared with standard gas chromatography mass spectrometry (GS-MS) methods, and provides a fast, user-friendly and low-cost alternative for quality control. Alternative systems in the literature to quantify TCA in cork samples include biosensors based on screen printed electrodes, 25 electrochemical displacement immunosensors 26 and cellular biosensors systems based on the bioelectric recognition.…”

Theoretical Investigation of Charge Transfer from NO+ and O2+ Ions to Wine-Related Volatile Compounds for Mass Spectrometry

“…Currently, the range of selective reagent ions in SRI-MS include H 3 O + , O 2 + , NO + , NH 4 + , Kr + , or Xe + . − The added advantages of SRI-MS comprise a broader range of detectable substances and the possibility to separate isomeric substances in some cases. Modern reactors allow one to strongly enhance the sensitivity of PTR-MS instruments and have been implemented for the analysis of specific compounds responsible for the unpleasant taint in wines . In parallel, SIFT-MS offers real-time analysis and the quantification of trace gas samples at ultratrace levels, although typical sensitivities are lower than PTR-MS detection limit (part per trillion or even part per quadrillion by volume), with rapid switching between reagent ions. ,, Due to frequent collisions with the carrier gas, usually He (or N 2 ), the reagent ions in SIFT-MS analysis are approximated at thermal equilibrium.…”