SIST EN 13805:2015

Overview

EN 13805:2014 - “Foodstuffs - Determination of trace elements - Pressure digestion” (CEN) specifies a standardized pressure-digestion procedure to mineralize food samples and prepare measurement solutions for trace-element analysis. The method is designed for closed-vessel digestion (conventional or microwave-assisted heating) using nitric acid (and, when needed, other acids and H2O2) and has been collaboratively tested with atomic absorption (flame, electrothermal, hydride, cold‑vapour) and ICP‑MS. Other detection techniques such as ICP‑OES, voltammetry or atomic fluorescence may also be combined with this digestion protocol.

Key Topics

• Scope and principle: Closed-vessel pressure digestion to convert food matrices into solutions suitable for trace-element determination; result relates to total element content depending on reagents and measurement technique.
• Reagents: High-purity acids to avoid contamination - HNO3 (≥65 % w/w); diluted HNO3 (1+9 v/v); HCl (≥30 % w/w); HF (≥40 % w/w); H2O2 (≥30 % w/w). Subboiling distillation is recommended for purifying acids if needed.
• Apparatus:
  • Pressure digestion vessels made of PTFE, FEP, PFA, quartz glass or similar acid‑resistant materials.
  • Systems with conventional heating, microwave-assisted digestion, or microwave autoclaves (autoclave filling pressure ≥ 40 bar where applicable).
  • Microwave systems must be equipped with reliable temperature measurement (internal or validated external sensors).
  • Cleaning tools: ultrasonic bath, stripping apparatus, subboiling distillation.
• Procedure & conditions:
  • Homogenize samples to avoid contamination; adapt sample mass to vessel capacity and carbon content.
  • Typical sample guidelines: carbon‑rich samples generally ≤ 200 mg fresh mass; less carbon content may allow up to ~3 g or 4 ml of liquid (without changing sample:acid ratio).
  • Typical acid volumes: ~3 ml HNO3; microwave systems may require more; 0.5–1 ml H2O2 can assist oxidation and mixing; add ≥0.5 ml HCl when required (e.g., Sn, Sb, Fe).
  • Safety: evaporate alcohol before acid addition; never use perchloric acid for pressure digestion; manage nitrogen oxide hazards.
• Quality control: Includes cleaning, blanks, certified reference materials and other QC measures (see clause 6.3.7).

Applications

• Accredited food‑analysis laboratories performing routine and regulatory trace element analysis (heavy metals, metalloids) in food and feed.
• Method validation and collaborative studies for laboratories using AAS, ICP‑MS, ICP‑OES, voltammetry or atomic fluorescence.
• Instrument manufacturers and lab managers specifying digestion protocols and safety/cleaning procedures.

Related Standards

• EN 13804 (Foodstuffs - Determination of elements and their chemical species - General considerations and specific requirements) - normative reference in EN 13805:2014.

Keywords: EN 13805:2014, pressure digestion, foodstuffs, trace elements, nitric acid digestion, microwave digestion, ICP‑MS, atomic absorption, sample preparation, pressure vessel, quality control.