Bestimmung von Sulfat mit Hilfe einer modifizierten FIA-Methode und Vergleich mit der Methode DIN 38405 Teil 5

Summary In general the DIN-method 38405, Part 5 is stipulated and used to determine sulphate in drinking and waste water. Since the processes of complexometric titration after ion exchange and precipitation described in those methods are rather time consuming and the number of samples to take is constantly increasing, it is opportune to adopt more rapid methods. For this purpose, flow injection analysis (FIA) is also suitable in addition to ion-chromotography.We have therefore revised and modified the analysis method ASTN 15/84, published by Tecator. This is based on the following principle:Methylthymolblue added to barium ions in an alkaline and alcoholic solution results in a blue complex with a peak at about 620 nm.Sulphate contained in the sample will precipitate out of the complex barium sulphate and the loss of coloration can be measured photometrically. In the revised version the method is especially suitable for routine tests. In order to prove that the results obtained are equivalent to those of the DIN-method, the equivalence of both methods has been examined according to DIN 38402, Part 71.The test has shown that the same results are obtained with both methods. Significant differences are not ascertainable.