The invention relates to a liquid, substantially anhydrous concentrate comprising at least 0.1 wt% of metal ions, 0.3 wt% carboxylic acid compound which is soluble in glycol, and at least 40 wt% of a glycol compound. The metal ion preferably is chosen from zinc, manganese, selenium, iron, copper, molybdenum, and magnesium and mixtures of these. The concentrate may contain metal ions in an amount of between 0.3-5 wt%, preferably 0.4-3 wt%.
