Overview
ISO/TS 11251:2019 specifies a standardized method for characterizing volatile components in single‑wall carbon nanotube (SWCNT) samples using evolved gas analysis coupled with gas chromatography–mass spectrometry (EGA/GCMS). The technical specification also covers EGA combined with mass spectrometry alone (EGA/MS) to determine gas‑evolution temperature ranges. It supports reproducible identification of gases evolved during controlled heating of SWCNTs while noting that qualitative and quantitative results can differ from bulk gas content because of heating effects and catalyst presence.
Key topics and requirements
- Scope and terms: Defines SWCNT, evolved gas analysis (EGA), EGA/MS and EGA/GCMS terminology consistent with ISO/TS 80004‑3.
- Principle: Use EGA/MS to locate temperature windows for gas release and EGA/GCMS to separate and identify individual volatile species.
- Apparatus: Typical setups include a furnace/temperature controller, cooling trap (for EGA/GCMS), GC capillary column and MS detector.
- Sample preparation: No dissolution/dispersion needed; samples must not be exposed to temperatures above 30 °C before analysis to avoid loss of volatiles.
- Sample mass and heating:
- Typical sample mass: 0.5–2 mg (weigh to 0.01 mg).
- Recommended heating rates: EGA/MS ~10–25 °C/min; EGA/GCMS ~45–65 °C/min (examples provided).
- Measurement procedures:
- Use EGA/MS to find gasification start/end temperatures and collect mass spectra.
- Use EGA/GCMS (with trap and GC column) to separate components and identify by EI mass spectra (typically 70 eV).
- Data analysis:
- Qualitative identification by matching MS spectra to spectral databases (e.g., NIST).
- Quantification based on TGA mass loss; evolved impurity content P given by: P = (W0 − Wt) / W0 × 100 (W0 = mass before heating, Wt = mass after).
- Uncertainties: Sources include oven/detector temperature fluctuation, mass analyser drift, and ionization energy variability.
- Report requirements: Reference the standard, identified components, mass loss (%), and instrumental/heating conditions.
Practical applications and users
- Who uses it: Materials scientists, nanomaterials labs, quality control teams, toxicologists, and instrument manufacturers working with SWCNTs.
- Applications:
- Identification of residual solvents, surfactants, and process-related volatiles in SWCNT production.
- Complementary analysis to thermogravimetric analysis (TGA) for impurity profiling.
- Process optimization, safety evaluations, and regulatory/compliance testing of carbon nanotube materials.
Related standards
- ISO/TS 80004‑3 (Nanotechnologies - Vocabulary - Part 3: Carbon nano‑objects) - referenced for terminology and definitions.
Keywords: ISO/TS 11251:2019, EGA/GCMS, EGA/MS, SWCNT, single‑wall carbon nanotube, evolved gas analysis, GC‑MS, volatile components, nanotechnologies.