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 |
Scope
1.1 This test method covers the determination of water from 0 to 2.0 % mass in liquid organic chemicals, with Karl Fischer reagent, using an automated coulometric titration procedure.
1.2 The values stated in SI units are to be regarded as the 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.
