ASTM E203-24 PDF

Full title and description

ASTM E203-24 — Standard Test Method for Water Using Volumetric Karl Fischer Titration. This standard describes procedures, apparatus, reagents (including pyridine-free formulations), and endpoint detection for determining free water and water of hydration in most solid and liquid organic and inorganic materials using the volumetric Karl Fischer titration technique.

Abstract

ASTM E203-24 provides a general guide to the application of volumetric Karl Fischer (KF) titration for measurement of water from trace levels to high concentrations by appropriate choice of sample size and reagent strength. The document addresses potentiometric (automatic) endpoint detection and includes guidance on interferences, sample preparation, and safety. For routine determination of very low water contents (generally ≤ 500 mg/kg), coulometric KF methods (see ASTM E1064 and related documents) are recommended as more suitable.

General information

• Status: Active standard (current edition).
• Publication date: January 11, 2024 (current edition approved in January 2024).
• Publisher: ASTM International.
• ICS / categories: 71.040.40 (Chemical analysis).
• Edition / version: E203-24 (current edition).
• Number of pages: 9.

Scope

This test method is intended as a general guide for applying volumetric Karl Fischer titration to determine free water and water of hydration in most solid and liquid organic and inorganic compounds. It is written for use with automatic titration systems that detect the KF endpoint potentiometrically (a manual visual endpoint procedure is typically included in appendices). Samples that are gaseous at room temperature are not covered. The standard covers use of pyridine-free KF reagents and gives guidance on choosing sample size, reagent concentration, and apparatus to cover a wide concentration range. It explicitly notes that coulometric KF (see ASTM E1064) is preferable for routine very-low-level water determinations.

Key topics and requirements

• Principle and reagents: Karl Fischer chemistry for volumetric titration; acceptance of pyridine-free reagents and solvent recommendations.
• Apparatus and endpoint detection: automatic potentiometric endpoint systems are the primary method; manual visual endpoint described in appendices.
• Sample preparation and sizing: guidance to select sample sizes and reagent concentrations to span parts-per-million up to percent-level water.
• Interferences and chemical treatments: discussion of common interferences (oxidizing/reducing substances, volatile solvents, reactive functional groups) and methods to eliminate or compensate for them.
• Performance considerations: comparative note that coulometric methods (ASTM E1064 and related) are more accurate for routine very-low-level water (generally ≤ 500 mg/kg).
• Safety and environmental notes: recommendation to consult current safety data sheets (SDS) for reagents and to follow laboratory safety practices.

Typical use and users

Used by analytical and quality-control laboratories across chemical manufacturing, pharmaceuticals, polymers, food and cosmetics, and petroleum-related industries where rapid and routine measurement of water content in solids and liquids is required. Typical users include laboratory analysts, QA/QC managers, method developers, and instrument manufacturers. The standard is applied where volumetric KF titration is an appropriate analytical choice (notably when water concentrations are moderate to high or when sample throughput requires volumetric methods).

Related standards

Key related standards and references include ASTM E1064 (coulometric Karl Fischer titration — recommended for very low water contents), ASTM D6304 (water determination in petroleum products by coulometric KF techniques), and various ISO standards on Karl Fischer methods (for example ISO 760 and ISO 8534 for pyridine-free KF in oils/fats, and ISO 12937/ISO 10337/ISO 10336 for petroleum/crude-oil KF methods). These documents provide complementary procedures, application-specific guidance, or alternative (coulometric or potentiometric) KF approaches.

Keywords

Karl Fischer; volumetric Karl Fischer titration; water determination; moisture analysis; pyridine-free reagent; potentiometric endpoint; free water; water of hydration; moisture in solids and liquids.

FAQ

Q: What is this standard?

A: ASTM E203-24 is the ASTM standard test method that specifies procedures for determining water content in solid and liquid materials using the volumetric Karl Fischer titration technique.

Q: What does it cover?

A: It covers sample handling and preparation, recommended reagents (including pyridine-free options), apparatus and potentiometric endpoint detection, treatment of interferences, and guidance for achieving accurate volumetric KF measurements across a wide concentration range (parts-per-million to percent-level). It excludes gaseous samples at room temperature.

Q: Who typically uses it?

A: Analytical chemists and laboratory quality-control personnel in chemical, pharmaceutical, polymer, food, cosmetic, and petroleum-related industries; instrument vendors and method developers also use the standard for method setup and validation.

Q: Is it current or superseded?

A: E203-24 is the current active edition (approved/updated in January 2024). Previous editions include E203-23 and earlier revisions; users should refer to the E203-24 text for the latest requirements.

Q: Is it part of a series?

A: It sits within a family of Karl Fischer methods: volumetric KF (ASTM E203) and coulometric KF (ASTM E1064 and several discipline-specific methods such as ASTM D6304). International ISO standards on Karl Fischer methods provide complementary or industry‑specific guidance.

Q: What are the key keywords?

A: Karl Fischer, volumetric titration, pyridine-free reagent, water determination, moisture analysis, potentiometric endpoint, free water, water of hydration.