ISO 16014-2:2019

Overview - ISO 16014-2:2019 (Universal calibration method)

ISO 16014-2:2019 is the ISO standard for determining the average molecular weight and molecular weight distribution of polymers using size-exclusion chromatography (SEC) with the universal calibration approach. Published as Part 2 of the ISO 16014 series (third edition, 2019), the standard specifies how to build and use a universal calibration curve - plotting lg([η]·M) versus elution time or volume - and how to convert SEC elution data into near-absolute molecular-weight values using the Mark–Houwink–Sakurada relationship ([η] = K·M^a).

Note: ISO 16014-2 is classed as a relative method (see ISO 16014-1) but, according to Annex A, typically yields average molecular weights and distributions equal or very close to absolute values.

Key topics and technical requirements

• Universal calibration curve: prepare using narrow-distribution polymer standards (e.g., polystyrene, PMMA); plot lg([η]·M) vs elution time (t) or volume (V = t·Q).
• Intrinsic viscosity and Mark–Houwink–Sakurada equation: use [η] = K·M^a to compute intrinsic viscosity or use directly measured [η] under the same elution conditions.
• Calculation steps:
  • Build universal calibration curve from standards.
  • Determine [η] or use K and a values to compute [η] for sample fractions.
  • Calculate molecular weight M at each elution time and compute average molecular weights, polydispersity, and differential/cumulative distributions per Clauses 9.2–9.4.
• Data acquisition & processing: follows procedures in ISO 16014-1 (baseline correction, signal intensity H at each t).
• Limitations and applicability: method assumes no specific interaction with column packing and that K and a are reasonably constant. It can be unreliable for strongly interacting polymers or extensively long-chain branched materials (see Annex A).
• Documentation: include calibration curve, standard information, apparatus and measurement parameters, and results in the test report (Clauses 11.2–11.4).

Applications and who uses this standard

• Laboratories performing polymer characterization by SEC seeking more universal / near-absolute molecular-weight results.
• R&D and QC teams in plastics, polymer manufacturing, coatings, adhesives, and materials science.
• Instrument vendors and service labs validating SEC systems and calibration procedures.
• Academic researchers comparing polymer architectures (linear vs branched) and seeking consistent inter-laboratory results.

Related standards

• ISO 16014-1 - General principles for SEC molecular-weight determination
• ISO 16014-3 - Low-temperature SEC method
• ISO 16014-4 - High-temperature SEC method
• ISO 472 - Plastics - Vocabulary

Keywords: ISO 16014-2:2019, universal calibration, size-exclusion chromatography, SEC, molecular weight distribution, intrinsic viscosity, Mark–Houwink–Sakurada, polymer characterization.