ISO 5381:1983 PDF

Starch hydrolysis products — Determination of water content — Modified Karl Fischer method

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Title (English):

ISO 5381:1983

Starch hydrolysis products — Determination of water content — Modified Karl Fischer method

Document status:: Active
Format:: Electronic (PDF)
Number of pages:: 6
Publication date:: August 1, 1983
Edition:: ISO IS 5381 edition 1 version 1
ICS:: 67.180.20

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Description (English):

Reaction of a solution of iodine, sulphur dioxide, pyridine and 2-methoxyethanol with the water contained in the product dispersed previously in a mixture of methanol and formamide. The method described in ISO 760 is improved by determing the content directly using the special solvent.

Technical details

Technical committee: ISO/TC 93 - Starch (including derivatives and by-products)
SKU: ISO 5381:1983

Abstract

Overview

ISO 5381:1983 specifies a modified Karl Fischer method for determining the water content of starch hydrolysis products. The standard adapts the general Karl Fischer titration (ISO 760) by directly using a methanol/formamide solvent to improve extraction and measurement of water from starch derivatives and by‑products. It covers reagents, apparatus, sample preparation, titration procedure, calculations and reporting.

Key topics and requirements

Scope: Determination of water in starch hydrolysis products using a stabilized Karl Fischer reagent (iodine, sulphur dioxide, pyridine and 2‑methoxyethanol) with methanol/formamide solvent.
Reagents:
- Stabilized Karl Fischer reagent (commercial or prepared per ISO 760).
- Methanol/formamide solvent: mix 700 ml anhydrous methanol with 300 ml anhydrous formamide.
- Sodium tartrate (Na2C4H4O6 · 2H2O) as standard for reagent standardization; check tartrate moisture by vacuum drying at 150 °C to constant mass (approx. 15.66% water).
Apparatus:
- Karl Fischer titrator or equivalent electrometric end‑point detection.
- One‑mark pipettes, 10 ml syringe (special design for viscous samples), weighing tube for solids, analytical balance.
- Platinum electrodes, titration vessel, burette (25 ml typical) and stirrer.
Procedure:
- Sample dispersion in methanol/formamide solvent to extract water.
- Standardize reagent daily using sodium tartrate; perform titration until stable end‑point.
- Carry out two determinations and use the mean if repeatability criteria are met.
Calculations and quality criteria:
- Water content calculated from reagent volume, reagent water equivalent (T) and sample mass (formula given in the standard).
- Repeatability limits specified (e.g., difference ≤ 0.05 % for water

Related standards

Mentioned in the description and other ISO standards

Overview

Key topics and requirements

Scope: Determination of water in starch hydrolysis products using a stabilized Karl Fischer reagent (iodine, sulphur dioxide, pyridine and 2‑methoxyethanol) with methanol/formamide solvent.
Reagents:
- Stabilized Karl Fischer reagent (commercial or prepared per ISO 760).
- Methanol/formamide solvent: mix 700 ml anhydrous methanol with 300 ml anhydrous formamide.
- Sodium tartrate (Na2C4H4O6 · 2H2O) as standard for reagent standardization; check tartrate moisture by vacuum drying at 150 °C to constant mass (approx. 15.66% water).
Apparatus:
- Karl Fischer titrator or equivalent electrometric end‑point detection.
- One‑mark pipettes, 10 ml syringe (special design for viscous samples), weighing tube for solids, analytical balance.
- Platinum electrodes, titration vessel, burette (25 ml typical) and stirrer.
Procedure:
- Sample dispersion in methanol/formamide solvent to extract water.
- Standardize reagent daily using sodium tartrate; perform titration until stable end‑point.
- Carry out two determinations and use the mean if repeatability criteria are met.
Calculations and quality criteria:
- Water content calculated from reagent volume, reagent water equivalent (T) and sample mass (formula given in the standard).
- Repeatability limits specified (e.g., difference ≤ 0.05 % for water

ISO 5381:1983 PDF

Technical details

Abstract

Overview

Key topics and requirements

Related standards

Abstract

Overview

Key topics and requirements

Related standards

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