ISO 19929:2017

Overview

ISO 19929:2017 specifies a standardized MALDI-TOF-MS method for determining the average molecular mass and mixture ratio of poly(ethylene glycol) (PEG) and its derivatives. The method covers PEG and derivatives with molecular masses from 500 g·mol−1 to 20 000 g·mol−1 and calculates composition using a calibration curve where peak area ratio is plotted against mass ratio. The standard can also be applied to other polymers having a monomeric unit similar to PEG.

Key Topics and Requirements

• Scope and applicability: Quantitative MALDI-TOF-MS analysis of PEG and related polymers (500–20 000 g·mol−1); applicable to mixtures of different end groups.
• Principle: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) with calibration of time-of-flight to molecular mass.
• Sample preparation: Guidance on preparation of polymer standards, polymer/matrix/salt solutions, and deposition on the MALDI target.
• Recommended reagents:
  • Matrices: α-cyano-4-hydroxycinnamic acid (CHCA) and dithranol.
  • Salts: lithium, sodium, potassium salts (e.g., iodides, trifluoroacetates).
  • Solvents: methanol and tetrahydrofuran (THF).
• Calibration:
  • Mass-axis calibration using synthetic or biopolymer standards (see Annex A).
  • Intensity-axis calibration through standard polymer mixtures; calibration curve constructed from peak area ratio vs mass ratio.
• Data processing and results:
  • Calculation of molecular mass distribution (MMD), number-average molecular mass (Mn), peak areas, and mass ratios.
  • Software-supported integration of isotopic peaks or use of the most abundant isotopic peak where necessary.
• Quality and reporting: Requirements for precision, instrument settings, calibration records, and test reports.

Applications and Users

ISO 19929 is intended for practical use in:

• Polymer manufacturing quality control (PEG products and PEGylated materials)
• Analytical and research laboratories conducting polymer characterization
• Pharmaceutical and biotech labs analyzing PEG-based excipients or PEGylated drugs
• Instrument manufacturers and service labs validating MALDI-TOF-MS methods
• Interlaboratory studies and standardization projects to ensure reproducible quantitative MALDI data

Typical applications include composition analysis of polymer mixtures, monitoring polymer synthesis and end-group differentiation, and quantitative comparison of polymer batches.

Related Standards

• ISO 10927:2011 - Determination of molecular mass and molecular mass distribution by MALDI-TOF-MS
• ISO 472 - Plastics - Vocabulary

Keywords: ISO 19929, MALDI-TOF-MS, poly(ethylene glycol), PEG, molecular mass, mixture ratio, calibration curve, polymer analysis.