ISO 7059:2023

Overview

ISO 7059:2023 - "Caprolactam for industrial use - Determination of absorbance at a wavelength of 290 nm" specifies a spectrometric method for measuring the ultraviolet absorbance of caprolactam solutions. The standard defines sample preparation, instrument requirements and calculation procedures to determine the absorbance at 290 nm for caprolactam intended for industrial use. It replaces the 1982 edition and modernizes measurement options and instrument requirements.

Key Topics and Requirements

• Scope: Determination of absorbance at 290 nm for caprolactam for industrial use using UV spectrometry.
• Sample preparation: Weigh (50.0 ± 0.1) g of caprolactam and dissolve in (50.0 ± 0.1) mL of distilled (or equivalent) water to obtain a 50% solution; bring solution to room temperature before measurement.
• Apparatus:
  • UV spectrometer capable of measurements at 290 nm.
  • Two quartz cells, optical path length 1 cm (preferred), or
  • One quartz flow‑through cell (1 cm) with a pump system.
• Measurement procedure:
  • Zero the spectrometer with water.
  • For two-cell method: measure test solution vs water and correct for any difference between the two cells by measuring both filled with water.
  • For flow‑through method: zero with water, measure sample, then rinse and verify rinsing effectiveness (recommended rinsing volume ~20–30× cell + tubing volume).
• Calculations: Report absorbance normalized to optical path length; include cell-correction term when using two cells.
• Precision requirement: Parallel measurements should not differ by more than 0.001 × l (where l is path length in cm).
• Reagents: Only distilled water or equivalent purity recommended.
• Test report content: sample identification, method reference, results and expression, instrument make/type, optical path length, rinsing volume, any deviations or unusual observations, and date.

Applications

• Quality control and acceptance testing of industrial caprolactam batches.
• Routine laboratory analysis to monitor UV‑absorbing impurities and product consistency.
• Process control in caprolactam production and polymer feedstock verification for nylon manufacture.
• Documentation for suppliers, purchasers, and regulatory or conformity assessment activities.

Who should use this standard

• QC/analytical chemists in chemical and polymer industries
• Laboratory managers and testing service providers
• Manufacturers and purchasers of caprolactam
• Regulatory and conformity assessment bodies involved with industrial chemicals

Related standards

• ISO 7059:1982 (previous edition) - superseded by this document.
• Other ISO standards on plastics and physico‑chemical testing (see ISO/TC 61 publications) for broader analytical and material requirements.

Keywords: ISO 7059:2023, caprolactam, absorbance 290 nm, UV spectrometer, quartz cell, flow‑through cell, industrial caprolactam, spectrometric method, quality control.