ISO 16014-1:2019

Overview

ISO 16014-1:2019 - "Plastics - Determination of average molecular weight and molecular weight distribution of polymers using size‑exclusion chromatography - Part 1: General principles" defines the general principles for using size‑exclusion chromatography (SEC) to determine the average molecular weight and molecular weight distribution of polymers. Part 1 sets out the method concept, essential reagents, apparatus, procedural steps, and data‑processing concepts. It explains when to use calibration curves from polymer standards versus absolute molecular weight data obtained by light‑scattering detection (SEC‑LS).

Key topics and requirements

• Principle: Separation by hydrodynamic volume; larger molecules elute earlier than smaller ones and concentration is monitored to produce an SEC chromatogram.
• Calibration approach:
  • Relative methods (ISO 16014-2 to -4): molecular weight at each elution time is determined from a calibration curve built with polymer standards of narrow molecular weight distribution.
  • Absolute method (ISO 16014-5 / SEC‑LS): calibration uses absolute molecular weight data from light‑scattering detection.
• Reagents: Requirements for eluents (high purity, particle‑free), column evaluation reagents, molecular weight standards characterized by absolute techniques, and appropriate additives when needed.
• Apparatus and system evaluation: Pumping system, injector, columns (theoretical plates, resolution, asymmetry), detectors (concentration and optionally LS), tubing, temperature control, and data acquisition hardware/software.
• Data acquisition & processing: Baseline determination, selection of calculation range, derivation of differential and cumulative molecular weight distributions, and calculation of average molecular weights (e.g., number‑ and mass‑average).
• Reporting & precision: Required information for test reports includes apparatus settings, calibration details, and computed results; the document also addresses precision considerations and system calibration checks.
• Important note: Mixed eluents can be used in some SEC methods but are not suitable for SEC‑LS, because selective adsorption of eluent components can bias light‑scattering measurements.

Applications

• Routine and research analysis of polymer molecular weight and polydispersity for:
  • Quality control in polymer production
  • Formulation and material development in plastics, coatings and adhesives
  • Comparative R&D studies and failure analysis
  • Regulatory and compliance testing where molecular weight profile is relevant

Who should use this standard

• Analytical chemists and laboratory managers in polymer and plastics industries
• Quality assurance professionals and process engineers monitoring molecular properties
• Instrument manufacturers and service providers implementing SEC or SEC‑LS systems
• Accreditation bodies and test laboratories preparing validated SEC methods

Related standards

• ISO 16014-2: Universal calibration method
• ISO 16014-3: Low‑temperature method
• ISO 16014-4: High‑temperature method
• ISO 16014-5: Light‑scattering (SEC‑LS) method
• ISO 472: Plastics - Vocabulary

Keywords: ISO 16014-1:2019, size‑exclusion chromatography, SEC, SEC‑LS, molecular weight distribution, average molecular weight, polymers, calibration curve, light‑scattering detection.