Significance and Use
The coulometric technique is especially suited for determining low concentrations of water in organic liquids that would yield small titers by the Karl Fischer volumetric procedure. The precision and accuracy of the coulometric technique decreases for concentrations of water much greater than 2.0 % because of the difficulty in measuring the small size of sample required. The test method assumes 100 % efficiency of coulombs in iodine production. Provision is made for verifying this efficiency. (See Table 1 and Note 6.)
TABLE 1 Sample Size Estimation
|Expected Water Content||Sample Size, mL|
|0 to 500 mg/kg||5 |
|500 to 1000 mg/kg||2 |
|1000 to 2000 mg/kg||1 |
|0.2 to 0.5 % mass||0.5 |
|0.5 to 2.0 % mass||0.1 |
1.1 This test method covers the determination of water from 0 to 2.0 % mass in most liquid organic chemicals, with Karl Fischer reagent, using an automated coulometric titration procedure. Use of this test method is not applicable for liquefied gas products such as Liquid Petroleum Gas (LPG), Butane, Propane, Liquid Natural Gas (LNG), etc.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 Review the current material safety data sheets (MSDS) for detailed information concerning toxicity, first-aid procedures, handling, and safety precautions.
1.4 This standard does not purport to address all of the safety problems, 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. Specific precautionary statements are given in Section 8.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
D1193 Specification for Reagent Water
D4672 Test Method for Polyurethane Raw Materials: Determination of Water Content of Polyols
E180 Practice for Determining the Precision of ASTM Methods for Analysis and Testing of Industrial and Specialty Chemicals
E203 Test Method for Water Using Volumetric Karl Fischer Titration
coulometric; Karl Fischer; organic liquids; pyridine; pyridine-free; water; Chemical analysis--chemicals; Coulometric Karl Fischer titration; Iodine reagent method; Karl Fischer reagent method--water content; Liquid chemicals; Liquids--laboratory applications; Organic chemicals; Volatile organic compounds (VOC)--water; Water content--chemicals
ICS Number Code 71.080.01 (Organic chemicals in general)
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Citing ASTM Standards
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