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ASTM E203-16
Standard Test Method for Water Using Volumetric Karl Fischer Titration
NORMA vydaná dňa 1.4.2016
Informácie o norme:
Označenie normy: ASTM E203-16
Poznámka: NEPLATNÁ
Dátum vydania normy: 1.4.2016
Kód tovaru: NS-638468
Počet strán: 9
Približná hmotnosť: 27 g (0.06 libier)
Krajina: Americká technická norma
Kategória: Technické normy ASTM
Kategórie - podobné normy:
Anotácia textu normy ASTM E203-16 :
Keywords:
free water, Karl Fischer reagent, pyridine-free, volumetric, water, water of hydration,, ICS Number Code 71.040.40 (Chemical analysis)
Doplňujúce informácie
| Significance and Use | ||||||||||||||||||||||||||||||||||||||||||||||||
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4.1 Titration techniques using KF reagent are one of the most widely used for the determination of water. 4.2 Although the volumetric KF titration can determine low levels of water, it is generally accepted that coulometric KF titrations (see Test Method E1064) are more accurate for routine determination of very low levels of water. As a general rule, if samples routinely contain water concentrations of 500 mg/kg or less, the coulometric technique should be considered. 4.3 Applications can be subdivided into two sections: (4.4 Water can be determined directly in the presence of the following types of compounds:
Note 1: Some acids, such as formic, acetic, and adipic acid,
are slowly esterified. For high accuracy with pyridine-based
reagents, use 30 to 50 % pyridine in methanol as the solvent. When
using pyridine-free reagents, commercially available buffer
solutions can be added to the sample prior to titration. With
formic acid, it may be necessary to use methanol-free solvents and
titrants Note 2: Examples of stable aldehydes are formaldehyde, sugars,
chloral, etc. Formaldehyde polymers contain water as methylol
groups. This combined water is not titrated. Addition of an excess
of NaOCHNote 3: Weak amines are considered to be those with
Note 4: Examples of stable ketones are diisopropyl ketone,
camphor, benzophenone, benzil, dibenzolacetone, etc.
Note 5: Sulfuric acid up to a concentration of 92 % may be
titrated directly; for higher concentrations see Note 13.
Note 6: Compounds subject to oxidation-reduction reactions in
an iodine-iodide system interfere.
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| 1. Scope | ||||||||||||||||||||||||||||||||||||||||||||||||
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1.1 This test method is intended as a general guide for the application of the volumetric Karl Fischer (KF) titration for determining free water and water of hydration in most solid or liquid organic and inorganic compounds. This test method is designed for use with automatic titration systems capable of determining the KF titration end point potentiometrically; however, a manual titration method for determining the end point visually is included as Appendix X1. Samples that are gaseous at room temperature are not covered (see Appendix X4). This test method covers the use of both pyridine and pyridine-free KF reagents for determining water by the volumetric titration. Determination of water using KF coulometric titration is not discussed. By proper choice of the sample size, KF reagent concentration and apparatus, this test method is suitable for measurement of water over a wide concentration range, that is, parts per million to pure water. 1.2 The values stated in SI units are to be regarded as standard. 1.3 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. Specific warnings are given in 3.1 and 7.3.3. 1.4 Review the current Safety Data Sheets (SDS) for detailed information concerning toxicity, first aid procedures, and safety precautions for chemicals used in this test procedure. |
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| 2. Referenced Documents | ||||||||||||||||||||||||||||||||||||||||||||||||
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