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This coulometric method is for determining water dissolved in liquid hydrocarbons, including sulfolane and the Carom process solvent. The method is generally applicable to traces of water, but can also be applied to mass-% levels. The lower limit of quantitation is 3 mass-ppm, but values below 10 mass-ppm are considered semi-quantitative. Common interferences include: aldehydes, ketones and mercaptans (see NOTE). ASTM D 1364, a volumetric Karl Fischer method, is generally used for samples containing greater than 7 mass-% water.
Since accurate measurement of water content in liquid hydrocarbons is primarily dependent on the ability to obtain and keep representative samples, the on-line technique described in UOP Method 344 is recommended, when applicable.