Overview
ISO 11480:2017 - "Pulp, paper and board - Determination of total chlorine and organically bound chlorine" specifies two validated laboratory procedures for measuring total chlorine and organically bound chlorine in all types of pulp, paper and board. The standard defines sample preparation, reagents, apparatus and calculation rules. The practical lower reporting limit is about 20 mg/kg. ISO 11480:2017 is published by ISO/TC 6 and replaces the 1997 edition, adding the Schöniger combustion option combined with ion chromatography.
Key topics and technical requirements
- Two alternative methods
- Microcoulometric method (Clause 4): sample combustion in a heated quartz tube, absorption of combustion gases and determination by microcoulometric titration. Faster, suitable for many replicate determinations.
- Schöniger method (Clause 5): Schöniger combustion followed by ion chromatography for chloride determination. More laborious but gives unambiguous chlorine results (no bromine interference).
- Sample pretreatment and sampling
- Protect samples from ambient contamination (polyethylene/aluminium packaging, gloves).
- Air-dry or determine dry matter per ISO 638 / ISO 287 as relevant; grind or cut samples to suit combustion equipment.
- Extraction for organically bound chlorine
- Inorganic chlorine is removed by extraction with a dilute acid nitrate solution before combustion when organically bound chlorine is required.
- Apparatus and reagents
- Combustion furnace (quartz tube), oxygen supply (gases must be free of chlorine and bromine), microcoulometer or ion chromatograph, filters, activated carbon and specified acids/reagents.
- Quality control and interferences
- Strict contamination control (lab air, reagents, filters).
- Bromine interference: microcoulometric results can include bromine as a positive bias; choose Schöniger + ion chromatography where bromine is possible.
- Performance
- Lower limit ~20 mg/kg; the microcoulometric cell sensitivity and repeatability are specified in the standard.
Practical applications and users
- Quality control and production monitoring in pulp, paper and board mills
- Environmental and regulatory labs assessing chlorinated organic content
- Recycled fiber testing and product certification
- R&D and analytical labs developing pulp/paper formulations or deinking/bleaching processes
- Consultants and compliance auditors who need traceable methods to report total and organically bound chlorine
Related standards
- ISO 638 - determination of dry matter content (oven-drying)
- ISO 287 - moisture content of a lot (oven-drying)
- ISO 11480:2017 aligns with ISO/TC 6 guidance and laboratory best practices for pulp and paper testing
Keywords: ISO 11480:2017, total chlorine determination, organically bound chlorine, pulp paper board testing, microcoulometric method, Schöniger method, ion chromatography, chlorine in paper, lab standard.