Overview
EN ISO 16968:2015 - Solid biofuels: Determination of minor elements specifies wet-chemical and instrumental approaches for measuring trace or minor elements in all solid biofuels. It covers the determination of As, Cd, Co, Cr, Cu, Hg, Mn, Mo, Ni, Pb, Sb, V, Zn and notes that Se, Sn, Tl can also be measured using the described methods. The standard describes sample decomposition (closed‑vessel digestion with HNO3, H2O2 and HF) and recommends suitable instrumental techniques for analysis.
Key topics and requirements
- Scope of elements: Arsenic, Cadmium, Cobalt, Chromium, Copper, Mercury, Manganese, Molybdenum, Nickel, Lead, Antimony, Vanadium, Zinc; other elements (Se, Sn, Tl) possible.
- Sample decomposition: Closed‑vessel digestion (fluoropolymer vessels) using nitric acid, hydrogen peroxide and hydrofluoric acid, heated in a microwave oven or resistance heating block.
- Analytical methods suggested: ICP‑OES, ICP‑MS, GF‑AAS, CV‑AAS, HG‑AAS; alternative methods (XRF, direct mercury analysers) may be used if validated with appropriate biomass reference materials.
- Quality assurance:
- Use of Certified Reference Materials (CRM/SRM) to check accuracy and calibration.
- If reagent blanks exceed ~30% of measured value, investigate ultra‑pure reagents and contamination control.
- Calibration with multiple CRMs may be required to address matrix effects or concentration-range limitations.
- Safety note: Hydrofluoric acid (HF) is hazardous - appropriate safety and handling procedures are mandatory.
- Supporting procedures: Includes guidance on digestion, detection, calibration, blank testing, calculations, and reporting; performance characteristics and example data are provided in informative annexes.
Applications and users
EN ISO 16968:2015 is practical for:
- Laboratories performing trace element analysis of biomass and solid biofuels.
- Biomass fuel producers and power plants needing fuel quality control, combustion performance and ash management data.
- Environmental and regulatory bodies monitoring toxic element content (e.g., cadmium, mercury) for compliance and safe ash recycling (fertiliser use).
- Research groups studying element uptake in energy crops, pollution transfer, and lifecycle/environmental impacts.
Benefits include improved data comparability, robust QA/QC using CRMs, and methods suitable for low‑level trace element detection in complex biomass matrices.
Related standards (selection)
Keywords: EN ISO 16968:2015, solid biofuels, minor elements, trace elements, microwave digestion, ICP‑MS, ICP‑OES, certified reference material, mercury, arsenic, cadmium.