DETERMINATION OF SULFUR AND TOTAL SULFUR-DIOXIDE IN WINES BY AN ICP-AES METHOD

Sulphur contents of the original sample and the sample free from sulph ur dioxide were determined by ICP-AES following nitric acid digestion under high pressure (using PAAR HPA equipment), and the total sulphur content was calculated from the difference between the results obtaine d. With the aim of preparing a sample free from sulphur dioxide, bound sulphur dioxide was released by sodium hydroxide, then after acidifyi ng by phosphoric acid, boiling was carried out. Relative standard devi ations of the results obtained for total sulphur, the sulphur without S(IV) and total sulphur dioxide were lower than 2.5, 3.5 and 5% respec tively. Various amounts of sulphur (in the form of Na2SO4), added to w ine samples, were successfully recovered between 95.5 and 104.9%. Base d on comparative analyses performed by a widely accepted classic metho d, the indirect method developed was found to be adequate for the dete rmination of total sulphur dioxide. The procedure is suitable for seri al tests. (C) 1998 Elsevier Science B.V.