ASTM D4928-24 - Standard Test Method for Water in Crude Oils by Coulometric Karl Fischer Titration

1.1 This test method covers the determination of water with true concentration range from 0.02 % to 5.00 % by mass or volume in crude oils using Procedures A and B and from 0.04 % to 3.75 % by mass or volume for Procedure C. Mercaptan (RSH) and sulfide (S⁻ or H₂S) as sulfur are known to interfere with this test method, but at levels of less than 500 μg/g [ppm(m)], the interference from these compounds is insignificant (see Section 6).

1.2 This test method can be used to determine water in the 0.005 % to 0.02 % by mass range, but the effects of the mercaptan and sulfide interference at these levels has not been determined. For the range 0.005 % to 0.02 % by mass, there is no precision or bias statement.

1.3 This test method is intended for use with standard commercially available coulometric Karl Fischer reagent.

1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific warning statements, see Section 8.

1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.