ISO 21392:2021

Overview - ISO 21392:2021 (Cosmetics, ICP‑MS heavy metals)

ISO 21392:2021 specifies a validated analytical method for quantifying trace levels of heavy metals in finished cosmetic products using the ICP‑MS / ICP‑MS technique after pressure‑assisted digestion. The standard covers seven target elements - chromium (Cr), cobalt (Co), nickel (Ni), arsenic (As), cadmium (Cd), antimony (Sb) and lead (Pb) - and describes sample digestion, instrument setup, calibration, quality control and method performance evaluation.

Key topics and technical requirements

• Scope and limits: Method is defined for Cr, Co, Ni, As, Cd, Sb and Pb; it can be extended to other elements only if the analyst demonstrates suitability.
• Sample preparation: Sealed pressure (microwave) digestion of cosmetic matrices with mineral acids (nitric acid ≥60% and hydrochloric acid ≥30%) at temperatures up to ~200 °C and pressures up to ~40 bar.
• Reagents and materials: Use Grade 1 ultrapure water (ISO 3696), acid‑cleaned labware (avoid borosilicate glass), certified stock solutions (analytes 1000 mg/L; internal standards Rh and Lu 1000 mg/L).
• Apparatus: Acid‑resistant, low‑contamination digestion vessels (recommend quartz for antimony issues); microwave digestion systems with calibrated temperature control.
• ICP‑MS analysis: Instrument tuning, internal standards (Rh, Lu), calibration blanks and mixed calibration standards are specified; quantification by ICP‑MS with appropriate operating conditions (see standard for instrument‑specific parameters).
• Quality control & validation: Requirements for blanks, recovery checks, control tests for antimony adsorption, accuracy profile and performance assessment (including annexes using ISO 5725 statistical approach).

Practical applications and users

Who will use ISO 21392:2021:

• Cosmetic laboratories performing regulatory compliance testing or product safety assessments.
• Manufacturers and contract testing labs validating in‑house ICP‑MS procedures for cosmetics.
• Quality assurance teams needing standardized methods for heavy metal trace analysis in finished cosmetic products. Practical benefits:
• Reliable, sensitive detection of trace heavy metals using ICP‑MS.
• Standardized digestion and QC procedures to improve inter‑laboratory comparability.
• Guidance to minimize contamination and matrix effects for accurate quantification.

Related standards and notes

• References ISO 3696 (Grade 1 water) and aligns with statistical validation approaches (ISO 5725 referenced in annexes).
• The method maximizes analytical detection of trace metals but does not evaluate systemic consumer exposure - additional toxicological assessment is required for exposure risk.

Keywords: ISO 21392, cosmetics analytical methods, ICP‑MS, heavy metals in cosmetics, trace element analysis, microwave digestion, antimony adsorption, method validation.