Medium Exchange Stripping Potentiometry for the Measurement of Labile Copper in White Wine

An efficient and effective procedure is described for the determination of the labile copper concentration in untreated white wine using medium exchange stripping potentiometry. Two rinse steps between the enrichment and stripping steps allowed measurement of labile concentration with good repeatability and reproducibility. The fraction of labile copper ranged from 13% to 91%, for 16 white wines, indicating the highly variable copper complexing character of the wine matrix. The methodology was applied to labile copper measurement during the oxidation of white wines.