Metals can be viewed as a fundamental component in all wines, and can find their way into wines by a variety of different sources. These analyses can be easily accomplished using flame atomic absorption (AA) spectrometry. The metals of concern which are routinely tested are the major elements copper, iron, potassium, sodium, calcium and magnesium.
Copper in wine can arise predominantly from vineyard sprays and the use of copper sulphate to remove hydrogen sulphide formed during fermentation, but less commonly can also be derived from copper based winery equipment.
Iron can exist in trace amounts in wine and arises mainly from the vineyard; however contamination can occur from steel equipment that is used in wine production. This is less of an issue nowadays with most winery equipment being made of stainless steel. However, any non stainless steel that comes into contact with grapes or wine (e.g. bins or hoppers) can contribute to the total iron content.
Excessive levels of calcium can cause stabilisation issues that may not be detected via routine stability tests, and high potassium levels may lead to tartrate deposits after bottling.