Clark Andrew C, Kontoudakis Nikolaos, Barril Celia, Schmidtke Leigh M, Scollary Geoffrey R
National Wine and Grape Industry Centre, Charles Sturt University, Locked Bag 588, Wagga Wagga, NSW 2678, Australia.
National Wine and Grape Industry Centre, Charles Sturt University, Locked Bag 588, Wagga Wagga, NSW 2678, Australia.
Talanta. 2016 Jul 1;154:431-7. doi: 10.1016/j.talanta.2016.03.099. Epub 2016 Mar 31.
The presence of copper in wine is known to impact the reductive, oxidative and colloidal stability of wine, and techniques enabling measurement of different forms of copper in wine are of particular interest in understanding these spoilage processes. Electrochemical stripping techniques developed to date require significant pretreatment of wine, potentially disturbing the copper binding equilibria. A thin mercury film on a screen printed carbon electrode was utilised in a flow system for the direct analysis of labile copper in red and white wine by constant current stripping potentiometry with medium exchange. Under the optimised conditions, including an enrichment time of 500s and constant current of 1.0μA, the response range was linear from 0.015 to 0.200mg/L. The analysis of 52 red and white wines showed that this technique generally provided lower labile copper concentrations than reported for batch measurement by related techniques. Studies in a model system and in finished wines showed that the copper sulfide was not measured as labile copper, and that loss of hydrogen sulfide via volatilisation induced an increase in labile copper within the model wine system.
葡萄酒中铜的存在会影响葡萄酒的还原、氧化和胶体稳定性，能够测量葡萄酒中不同形态铜的技术对于理解这些变质过程尤为重要。迄今为止开发的电化学溶出技术需要对葡萄酒进行大量预处理，这可能会干扰铜的结合平衡。在流动系统中，利用丝网印刷碳电极上的薄汞膜，通过恒电流溶出电位法和介质交换直接分析红葡萄酒和白葡萄酒中的不稳定铜。在优化条件下，包括500秒的富集时间和1.0μA的恒电流，响应范围在0.015至0.200mg/L之间呈线性。对52种红葡萄酒和白葡萄酒的分析表明，与相关技术的批次测量相比，该技术通常提供的不稳定铜浓度更低。在模型系统和成品葡萄酒中的研究表明，硫化铜未被测量为不稳定铜，并且通过挥发损失硫化氢会导致模型葡萄酒系统中不稳定铜的增加。
