Overview
EN ISO 21078-1:2008 - Determination of boron(III) oxide in refractory products (Part 1) specifies validated laboratory methods for measuring total boron(III) oxide (boric oxide) in oxidic materials used for ceramics, glass and glazes. The standard applies to mass fractions of 0.01 % or greater and was prepared by ISO/TC 33 in collaboration with CEN/TC 187. It defines sample preparation, four analytical procedures, and rules for expression and reporting of results.
Key topics and technical requirements
- Applicable range and methods
- Alkaline titrimetry - suitable for samples with > 0.5 % B2O3 (fusion and titration; mannitol method with pH end points described in the standard).
- Azomethine H spectrophotometry - for 0.01 % to 2.5 % B2O3.
- Curcumin (rothocyanine) spectrophotometry - for 0.01 % to 1.0 % B2O3.
- ICP-AES (inductively coupled plasma atomic emission spectrometry) - for 0.01 % to 15 % B2O3 (extendable to ~30 % with modified fluxes).
- Sample preparation
- Sampling and reduction procedures for bricks and unshaped refractories (crush to pass 6.7 mm, then grind to 300 µm; laboratory test sample to 106 µm).
- Drying requirements for wet samples (air-bath/oven at 110 °C ± 5 °C, minimum drying times given).
- Test portion weighing to nearest 0.1 mg; duplicate determinations and reagent blank corrections required.
- Quality control
- Simultaneous duplicate determinations and blank tests.
- Annex A provides interlaboratory test results (informative) to support method performance.
- Reagents and apparatus
- Lists of required reagents (e.g., sodium hydroxide, mannitol) and apparatus (muffle furnace, pH meter, ICP-AES) are specified.
Applications and users
- Who uses it
- Quality control and analytical laboratories in refractory, ceramics, glass and glaze industries.
- Raw-material suppliers, R&D groups, compliance testing bodies and failure-analysis labs.
- Practical uses
- Routine compositional testing to control boron content in raw materials and finished refractory products.
- Compliance verification, product specification, process control and formulation development where boron content affects melting, viscosity or refractory properties.
Related standards
This standard is essential for accurate, reproducible measurement of boric oxide in oxidic refractory materials and supports regulatory and quality requirements in ceramics and glass manufacturing.
