【国外标准】 Standard Test Method for Maleic Acid in Maleic Anhydride by Potentiometric Titration (Withdrawn 2012)

The maleic acid content is usually an indication of exposure to moisture in air. Maleic anhydride reacts with moisture to form maleic acid.1.1 This test method covers the determination of free maleic acid in refined maleic anhydride by potentiometric titration.1.2 This test method is applicable for all concentrations of maleic acid; however, it is primarily used for concentrations below 0.5 %.1.3 The following applies to all specified limits in this standard: For purposes of determining conformance with this standard, an observed value or a calculated value shall be rounded off "to the nearest unit" in the last right-hand digit used in expressing the specification limit, in accordance with the rounding-off method of Practice E 29.1.4 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 and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Section 7.