Overview
EN ISO 16948:2015 - titled "Solid biofuels - Determination of total content of carbon, hydrogen and nitrogen (ISO 16948:2015)" - is a CEN-endorsed, instrumental method standard for measuring the total carbon (C), hydrogen (H) and nitrogen (N) contents of solid biofuels. Adopted in 2015 and superseding EN 15104:2011, this standard describes combustion-based analytical procedures used in routine laboratories and research to produce reliable elemental data for quality control and combustion calculations.
Key topics and technical requirements
- Principle: A known mass of sample is combusted in oxygen (or oxygen/carrier gas). Combustion products (CO2, H2O, N2 and possibly NOx, halides, sulfur products) are processed so interfering species are removed or reduced, and the mass fractions of CO2, H2O and N2 are quantified by instrumental gas analysis.
- Instrumental methods: Emphasis on modern instrumental elemental analyzers; preferred over older chemical methods for many applications.
- Reagents and gases: Use of high-purity reagents; carrier gas typically helium (or manufacturer-specified alternative); oxygen supplied per instrument requirements. Warning: many reagents are toxic/corrosive.
- Calibration: Requires high-purity calibration substances (examples provided) and use of certified reference materials (CRMs or SRMs) to validate accuracy and traceability.
- Sample preparation and test portion: References procedures for representative sampling and preparation to ensure reliable results.
- Expression of results and performance: Specifies how to report mass fractions and includes performance characteristics and test reporting requirements.
- Limitations: Notes that the Kjeldahl method can be more reliable for very low nitrogen contents (e.g.,
