By David Simmons, Study Director II, Chemistry
To continue to assure the most accurate water analysis utilizing the coulometric Karl Fischer test method, Nelson Laboratories recently upgraded its Karl Fischer coulometric titrator and added the additional feature of a Stromboli oven sample changer. The Stromboli is a multi-sample platform connected with an integrated drying oven. This added feature allows for the analysis of multiple samples, a blank, and drift value in a single sequence. Automatic sampling allows for greater productivity which means shorter analysis times for the customer. We are able to analyze solid and semi-solid samples without the need of a solvent. This improves accuracy as well as aids in shorter analysis times. We can test samples that cannot be suitably extracted with a solvent, and finally it helps to eliminate the potential of side reactions which may lead to inaccurate values.
The drying oven allows for controlled heating of the extraction vessel on the bottom and sides. Nelson Laboratories has validated the analysis at both 100°C and 180°C. This allows for some control in the analysis of surface or entrained moisture to that of molecularly bound moisture. A needle pierces the aluminum seal on the top of the extraction vessel and a secondary silicone seal ensures no atmospheric moisture can enter during the analysis. The controlled heating of a test sample drives moisture from the sample into a stream of dry nitrogen which carries the moisture to the reaction vessel. Once in the reaction vessel the coulometric titrator is able to accurately measure the transferred moisture.
The Karl Fischer coulometric titration is one of the most sensitive methods for water determination available. This method is specific to water, unlike other methods where the measured value may include any volatile substance. Values may be accurately measured to as low as 50 micrograms of water.
The Karl Fischer test is a simple, yet sensitive test designed to help manufacturers evaluate whether the moisture content of their products is correct based on their established criteria. Nelson Laboratories can provide additional information on Karl Fischer testing along with the benefits of the Stromboli Karl Fischer oven sample changer.