SIST EN ISO 54321:2021 PDF

Overview

EN ISO 54321:2021 - published by CEN and identical to ISO 54321:2020 - specifies standardized procedures for the digestion of aqua regia soluble fractions of elements in soil, treated biowaste, sludge and waste. The standard defines two validated digestion approaches to extract the aqua regia–soluble portion of metals and metalloids prior to instrumental analysis. It notes that aqua regia digestion does not necessarily achieve total decomposition of samples; results represent the aqua regia–soluble fraction and are considered fit for most environmental monitoring and protection purposes.

Key Topics

• Scope and applicability
  • Targets environmental matrices such as municipal/industrial sludge, compost, biowaste, soils, ashes and waste residues.
  • Applicable to elements including: Aluminium (Al), Antimony (Sb), Arsenic (As), Barium (Ba), Beryllium (Be), Boron (B), Cadmium (Cd), Calcium (Ca), Chromium (Cr), Cobalt (Co), Copper (Cu), Iron (Fe), Lead (Pb), Magnesium (Mg), Manganese (Mn), Mercury (Hg), Molybdenum (Mo), Nickel (Ni), Phosphorus (P), Potassium (K), Selenium (Se), Silver (Ag), Sodium (Na), Strontium (Sr), Sulfur (S), Tellurium (Te), Thallium (Tl), Tin (Sn), Titanium (Ti), Vanadium (V), and Zinc (Zn). Other elements may be included after user verification.
• Two digestion methods
  • Method A - Thermal heating under atmospheric conditions
    • A1: Reflux boiling
    • A2: Heating block with containers (boiling time specified)
  • Method B - Microwave digestion in closed vessels with temperature control
• Procedure components
  • Reagents (aqua regia defined as 1 volume HNO3 : 3 volumes HCl)
  • Apparatus, blank tests, sample preparation, interferences and sources of error
  • Test reporting and validation data (repeatability and reproducibility annexes)
• Safety and limitations
  • Strong oxidizing acids, high temperatures/pressures - perform in fume hood and use laboratory-grade microwave systems; trained personnel only.
  • Results represent aqua regia–soluble metals, not necessarily total metal content.

Applications

• Routine environmental monitoring of soils, sludges, treated biowaste and waste streams for regulatory compliance and risk assessment.
• Pre-treatment step before analysis by ICP-MS, ICP-OES, AAS or comparable elemental techniques.
• Waste characterization for landfill acceptance, remediation planning, compost quality control and industrial waste management.
• Laboratories seeking harmonized, validated aqua regia digestion methods for multi-element analysis.

Related standards

• ISO 11466, EN 13657 and EN 16174 - similar aqua regia/reflux procedures (differences in waiting/heating times noted).
• Dutch NEN 6961 - source of the heating block procedure included in this standard.

EN ISO 54321:2021 is a practical, validated reference for laboratories and environmental professionals performing aqua regia digestion to obtain comparable, fit-for-purpose data on metal content in solid environmental matrices.