Overview
ISO 20714:2019 specifies a validated gas chromatographic method (GC-FID) for the quantitative determination of nicotine, propylene glycol (PG) and glycerol in e‑liquids used in electronic nicotine delivery devices (ENDS). The standard sets out sample preparation, chromatographic conditions, calibration, expression of results (mg/g), and reporting requirements to ensure reliable and comparable e‑liquid analysis across laboratories.
Key topics and technical requirements
- Scope & principle: Dilute an e‑liquid test portion in isopropanol containing internal standard(s) and analyse by capillary gas chromatography with flame ionization detection (GC‑FID).
- Sample preparation: Example procedure-0.100 g sample diluted with 10 mL isopropanol/internal standard solution; seal, mix and analyse as soon as possible (or store 2–8 °C in the dark).
- Reagents & internal standards: High‑purity reagents. Recommended internal standards include quinaldine, 1,3‑butanediol, n‑heptadecane, n‑octadecane; dilution solution typically isopropanol with internal standard at specified concentrations.
- Calibration: At least five calibration solutions covering expected concentration ranges. Collaborative study linear ranges: nicotine 0.005–1.5 mg/mL; propylene glycol and glycerol 0.12–10 mg/mL. Calibration uses area ratios to internal standards and linear regression (not forced through origin).
- GC conditions (examples): Capillary column DB‑ALC1 (30 m × 0.32 mm × 1.8 µm) or equivalent; injection 1 µL split (e.g., 50:1); oven temperature program and detector/carrier gas flows are provided as example settings-users should optimize separation for their column and matrix.
- Results & reporting: Results expressed as mg/g using the formula w = (c × V) / m (c = concentration from calibration, V = dilution volume, m = sample mass). Report nicotine, PG and glycerol to three significant figures, sampling and method details, and any conditions affecting results.
- Performance: Interlaboratory study (up to 19 labs) provides repeatability and reproducibility estimates for different sample levels.
Applications and users
ISO 20714:2019 is intended for:
- Analytical and quality control laboratories performing e‑liquid composition testing.
- ENDS manufacturers verifying product formulations and label claims.
- Regulators and public health labs conducting compliance testing.
- Research groups studying e‑liquid chemistry or exposure assessment.
Benefits include standardized GC‑FID e‑liquid analysis, improved comparability of nicotine and solvent (PG/glycerol) measurements, and documented method validation parameters.
Related standards
- ISO 5725‑1 (accuracy of measurement methods)
- ISO 10315 (nicotine by GC in smoke condensates)
- ISO 13276 (nicotine purity determination)
- CORESTA e‑cigarette technical reports and ISO/TC 126 committee outputs
Keywords: ISO 20714:2019, e‑liquid analysis, GC‑FID, nicotine determination, propylene glycol, glycerol, electronic nicotine delivery devices, e‑liquid testing, calibration, internal standard.