ISO 13885-2:2020

Overview

ISO 13885-2:2020 specifies a standardized gel permeation chromatography (GPC / size exclusion chromatography, SEC) method using N,N‑Dimethylacetamide (DMAC) as the eluent for determining the molar‑mass distribution and average molar masses Mn (number average) and Mw (weight average) of polymers soluble in DMAC. The document defines instrument configuration, calibration, sample preparation, data acquisition and evaluation procedures, and limits of applicability (e.g., polymers with Mw > 1×10^6 g·mol‑1 or elution outside the calibration range).

Key technical topics and requirements

• Scope & limitations
  • Applies only to polymers soluble in DMAC.
  • Not suitable when specific interactions (adsorption) occur, or when Mw > 10^6 g·mol‑1 or elution falls outside calibration limits.
  • No built‑in correction for peak broadening; use absolute methods (membrane osmometry, light scattering) for absolute molar masses.
• Apparatus & materials
  • Eluent: DMAC; reservoir must protect against atmosphere/light and be degassed (bubble trap, helium purge, vacuum).
  • Corrosion risk: use high‑quality steel or titanium for wetted parts and capillaries.
  • Pump: smooth, pulse‑free flow - nominal 1.0 mL·min‑1; flow variation ≤ 0.1%.
  • Injection system: rapid, reproducible injections; avoid memory effects.
  • Columns: series-packed porous material (typically styrene/divinylbenzene, S/DVB); temperature control required.
  • Detector: concentration‑sensitive detector (commonly differential refractometer).
• Analytical procedure
  • Sample dissolution and dilution to < 5 g·L‑1; inject aliquot into GPC.
  • Calibration using polymer standards; plot calibration curve and check elution limits (Clause 7.6, Annex C).
  • Data processing: baseline determination, net chromatogram, calculation of Mn, Mw, Mw/Mn (polydispersity), and distribution curves.
• Quality & reporting
  • Sections cover precision (repeatability, reproducibility) and required test report content (equipment, calibration, evaluation, sample data).

Practical applications and users

• Intended for laboratories and quality control in:
  • Paints, varnishes and polymer raw materials (ISO/TC 35 scope).
  • Polymer manufacturers, R&D groups, materials testing labs, and contract analytical services requiring consistent relative molar‑mass distributions for DMAC‑soluble polymers.
• Use cases:
  • Routine QC of polymer batches soluble in DMAC.
  • Comparative studies of polymer molecular‑weight distribution.
  • Method standardization where DMAC is the preferred solvent.

Related standards and annexes

• Part of the ISO 13885 series; normative references include ISO 1513, ISO 4618, ISO 15528.
• Informative annexes: Annex A (column size conversions), Annex B (example standard data sheet), Annex C (explanations, calibration limits).
• For absolute molar mass methods, consult membrane osmometry and light‑scattering standards and guidance.