Copper In Wine Research Articles

Determination of heavy metals in real samples by anodic stripping voltammetry with mercury microelectrodes : Part 1. Application to Wine

Differential-pulse anodic stripping voltammetry with a mercury microelectrode is used for the determination of zinc, cadmium, lead and copper in wine at its natural pH without pretreatment. The effects of the matrix on the stripping peaks are studied in detail by varying the concentration of the metals. Intermetallic (CuZn) interferences and the effects of oxygen are described. The results obtained for the labile metal contents varied from 2 μg l −1 for cadmium to 148 μg l −1 for zinc; standard addition plots were linear over about two orders of magnitude above these levels, demonstrating the negligible effect of organic matter. Acidification of the sample with hydrochloric acid to pH 1 allowed the total metal contents to be determined. The reliability of the method was tested by comparison with the results obtained with atomic absorption spectrometry; the differences were within 10–20%.

Determination of copper in wine by potentiometric-stripping analysis.

The application of potentiometric-stripping analysis (PSA) to the determination of copper in wine is described. The need for some form of sample pre-treatment is demonstrated and a procedure, based on a nitric acid pre-treatment, has been developed. The results obtained by this method compare favourably with those obtained by atomic absorption spectrometry. The usefulness of the PSA technique for the routine determination of copper in a wine laboratory is discussed.

Toxic trace metals in food. I. A new voltammetric procedure for toxic trace metal control of wines.

A new highly sensitive and particularly reliable analytical procedure for the precise determination of the most relevant toxic trace metals cadmium, lead and copper in wine is presented. It consists of a simple and convenient sample pretreatment by UV irradiation (1,5 h, 500-W-Hg-lamp) to release the toxic trace metals bound by organic substances and subsequent voltammetry (DPASV) of cadmium and lead simultaneously at a mercury film electrode (MFE) formed in situ on a vitreous carbon carrier and of copper on a gold electrode. Particular emphasis has been placed on the efficient exclusion of interference due to contamination. Only special wines, with more than 10% of sugar, require substitution of UV irradiation by a wet digestion also described. The procedure may be easily expanded to include the determination of mercury and zinc.

Bestimmung von Cadmium, Blei und Kupfer in Wein durch Differentialpulse-anodic-stripping Voltammetrie

The simultaneous determination of cadmium, lead and copper in wine by differential pulse anodic stripping voltammetry at the hanging mercury drop electrode is described. The wine samples are decomposed in a mixture of sulphuric acid and hydrogen peroxide at 180° C. The procedure is controlled by recovery tests and compared with other wet digestion methods. The results for ten red and white wine samples of different origin are given. The lead values (65–230 ppb) were below the accepted maximum level for this metal, but some of the wines contained relatively large amounts of copper (0.08–1.04 ppm). Very low values (1.4–6.6 ppb) were found for cadmium.

The in situ determination of iron and of copper in wine

The improved determination of both iron and copper in red and white wines has been developed which avoids the preliminary process of ashing the sample before processing the ash for the actual evaluation of these two troublesome impurities. The new procedure employs bathocuproine and bathophcnanthroline as completing ligands with spectrophotometric determination of the Cu and the Fe in situ. The new method is economical in required analysis time, manipulative details and in quantity of sample involved. It has been shown that the new method is comparable in accuracy to previous published procedures, and as control analyses substitute wet ashing technique, the HNO 3-HCIO 4 destruction of organic matter, was applied.