ISO 8112:2023

Caprolactam for industrial use — Determination of colour of 50 % aqueous caprolactam solution, expressed in Hazen units (platinum-cobalt scale) — Spectrometric method

This document specifies a spectrometric method of determining the colour, expressed in Hazen units, of a 50 % aqueous caprolactam solution as a measure of coloured impurities content of the sample.

Caprolactame à usage industriel — Détermination de la coloration d'une solution aqueuse à 50 % de caprolactame, exprimée en unités Hazen (échelle platine-cobalt) — Méthode spectrométrique

General Information

• Status: Published
• Publication Date: 16-Jul-2023
• ICS: 71.080.30 - Organic nitrogen compounds
• Technical Committee: ISO/TC 61/SC 5 - Physical-chemical properties
• Drafting Committee: ISO/TC 61/SC 5 - Physical-chemical properties
• Current Stage: 6060 - International Standard published
• Start Date: 17-Jul-2023
• Due Date: 22-Sep-2024
• Completion Date: 17-Jul-2023

Relations

• Revises: ISO 8112:1984 - Caprolactam for industrial use — Determination of colour of 50 % aqueous caprolactam solution, expressed in Hazen units (platinum-cobalt scale) — Spectrometric method
• Effective Date: 06-Jun-2022

Overview

ISO 8112:2023 specifies the spectrometric method for determining the colour of a 50% aqueous caprolactam solution, with results expressed in Hazen units (platinum-cobalt scale). This standardized procedure is a key quality control measure for industrial caprolactam, widely used as a monomer in the production of polyamide (nylon) materials. Monitoring the colour provides insights into the level of coloured impurities, helping ensure compliance with industry requirements and maintaining product consistency.

Key Topics

• Colour Measurement: This standard focuses on evaluating the colour of caprolactam solutions, providing a quantitative measure in Hazen units, which directly correlates to impurity assessment.
• Spectrometric Method: Absorbance is measured at a wavelength of 390 nm using a spectrometer with a 50 mm optical path length, offering a reliable, repeatable analysis method.
• Result Expression: The measured absorbance is converted into Hazen units using a standard calculation factor, aligning results with established platinum-cobalt scale references.
• Apparatus and Conditions:
  • Use of optical glass or quartz cells or a flow-through cell with a 50 mm path.
  • Precise solution preparation and temperature management are integral to accuracy.
• Reporting Requirements: Detailed documentation of sample identification, methodology, results, instrument details, and observations is mandated to support traceability and transparency.

Applications

Implementing ISO 8112:2023 delivers significant benefits across the industrial caprolactam supply chain:

• Quality Control in Manufacturing: Ensures the caprolactam used in nylon or polyamide production meets strict colour and impurity benchmarks, essential for high-performance materials.
• Supplier Verification: Enables standardized comparison between batches or suppliers, contributing to procurement decisions and supplier evaluations.
• Research and Development: Supports the evaluation of process improvements or alternative purification methods by providing objective impurity analysis.
• Regulatory Compliance: Aligns laboratory practices with internationally recognized methods, facilitating certification processes and market access, especially where Hazen colour units are a procurement requirement.

Related Standards

Implementing ISO 8112:2023 often involves reference to or integration with these related standards:

• ISO 2211: "Liquid chemical products - Measurement of colour in Hazen units (platinum-cobalt scale)" - provides the foundational procedure for colour measurement and calibration in Hazen units.
• ISO/TC 61, Plastics: The technical committee responsible for physical-chemical characterization standards in polymer and monomer supply chains.
• Additional relevant standards may include methods for impurities testing, solution preparation, and spectrometric analysis, ensuring a robust laboratory framework for caprolactam evaluation.

For organizations in the chemical and plastics industries, adopting ISO 8112:2023 facilitates consistent, objective colour assessment in caprolactam, directly supporting product quality, process efficiency, and regulatory requirements.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 8112
Second edition
2023-07
Caprolactam for industrial use —
Determination of colour of 50 %
aqueous caprolactam solution,
expressed in Hazen units (platinum-
cobalt scale) — Spectrometric method
Caprolactame à usage industriel — Détermination de la coloration
d'une solution aqueuse à 50 % de caprolactame, exprimée en unités
Hazen (échelle platine-cobalt) — Méthode spectrométrique
Reference number
© ISO 2023
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ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 1
6 Apparatus . 1
7 Procedure .2
8 Expression of results . 2
9 Test report . 3
iii
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This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 5, Physical-
chemical properties.
This second edition cancels and replaces the first edition (ISO 8112:1984), which has been technically
revised.
The main changes are as follows:
— the option to use a flow-through cell for the absorption measurement has been added;
— the temperature of measured solution has been taken into account.
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