Increasing the Efficiency and Accuracy of Labile Cu Measurement in Wine with Screen-Printed Electrodes
1
School of Agricultural and Wine Sciences, Charles Sturt University, Wagga Wagga, NSW 2678, Australia
2
National Wine and Grape Industry Centre, Wagga Wagga, NSW 2678, Australia
*
Author to whom correspondence should be addressed.
Chemosensors 2018, 6(3), 35; https://doi.org/10.3390/chemosensors6030035
Received: 8 August 2018
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Revised: 14 August 2018
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Accepted: 14 August 2018
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Published: 17 August 2018
(This article belongs to the Special Issue Printed Electroanalytical Tools for De-Centralized Applications)
Development of oxidative and reductive flavors in wine can be influenced by the concentration and form of Cu within the wine. Electrochemical techniques have been devised to quantitate electrochemically active Cu (labile) in wine, as opposed to inactive Cu (non-labile). However, the electrochemical methods to measure labile Cu may be biased by the wine matrix, require lengthy calibration processes and/or unduly perturb the wine matrix during measurement. In this study, medium exchange stripping potentiometry was utilized with a thin mercury film on a screen-printed carbon electrode to provide a quantitation method that could largely overcome these limitations. The best average recoveries for 0.040 mg/L of labile Cu of 101 ± 15% (n = 12) were observed using composite calibration graphs prepared in oxidized wines and on multiple electrodes and using Pb as an internal standard. Composite calibration curves performed on different electrodes to the sample analysis were as effective in quantifying labile Cu as calibration curves performed on the same electrode as the sample. The results allow selection of a quantitation procedure that will suit the required speed and accuracy of labile Cu determination.
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Keywords:
Cu speciation; wine; quantitation; potentiometric stripping analysis; stripping potentiometry; calibration; screen-printed electrode; thin mercury film
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Link: http://Supplementary Figure 1.
Description: Supplementary Figure 1. The impact of a bubble in the electrode flow cell on peak areas, peak ratios and calibration graphs: (a) the peak areas for Cu (■) and Pb (), and the Cu/Pb stripping ratio (●); (b) the calibration graphs generated using Cu/Pb stripping ratios in white wine (●) and model wine (■); and (c) the calibration graphs generated using Cu stripping times in white wine (●) and model wine (■). For (a), the order of analysis is: determination (det.) 1-3, model wine + 0.080 mg/L Cu; det. 4-6, model wine + 0.04 mg/L Cu; det. 7-9, model wine + 0.020 mg/L Cu; det. 10-12, white wine + 0 mg/L Cu; det. 13-15, white wine + 0.040 mg/L Cu; and det. 16-18, white wine + 0.080 mg/L Cu. The bubble event occurred from analysis numbers 11 to 14.
MDPI and ACS Style
Clark, A.C.; Kontoudakis, N. Increasing the Efficiency and Accuracy of Labile Cu Measurement in Wine with Screen-Printed Electrodes. Chemosensors 2018, 6, 35. https://doi.org/10.3390/chemosensors6030035
AMA Style
Clark AC, Kontoudakis N. Increasing the Efficiency and Accuracy of Labile Cu Measurement in Wine with Screen-Printed Electrodes. Chemosensors. 2018; 6(3):35. https://doi.org/10.3390/chemosensors6030035
Chicago/Turabian StyleClark, Andrew C., and Nikolaos Kontoudakis. 2018. "Increasing the Efficiency and Accuracy of Labile Cu Measurement in Wine with Screen-Printed Electrodes" Chemosensors 6, no. 3: 35. https://doi.org/10.3390/chemosensors6030035
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