Overview
ISO 317:1984 specifies a spectrometric method for the determination of arsenic content in manganese ores and concentrates. The method applies to products with arsenic in the range 0.001 to 0.2 % (m/m) and is intended to be read in conjunction with ISO 4297 (general instructions for chemical analysis) and related sampling standards. The standard combines chemical decomposition, reduction and distillation with a final spectrometric measurement of a molybdenum-derived coloured complex.
Key Topics
- Scope and applicability: Designed for manganese ores and concentrates with arsenic 0.001–0.2 % (m/m).
- Analytical principle: Decompose the test portion with hydrochloric, nitric and sulfuric acids; reduce As(V) to As(III); distil As(III) as arsenic trichloride; oxidize and form the arsenomolybdate heteropolyacid and reduce to a blue complex for spectrometric measurement.
- Reagents (selected from the standard): potassium bromide, hydrazine sulfate, ascorbic acid, sulfuric, hydrochloric, nitric and perchloric acids, ammonium molybdate and prepared arsenic standard solutions.
- Apparatus: Usual laboratory glassware plus a dedicated distillation apparatus illustrated in the standard and a spectrometer capable of measurements at 840 nm or in the 630–700 nm range.
- Sample requirements: Test sample crushed to not exceed 100 µm, air-dried under laboratory conditions. Sampling and sample preparation reference ISO 4296/1 and ISO 4296/2.
- Key procedural parameters: heat and double evaporation to fumes of sulfuric acid, distillation at about 108 °C until ~two-thirds volume distilled, heat dry residues at 120–130 °C for 40–60 min, and colour development using ammonium molybdate and ascorbic acid prior to spectrometric reading.
Applications
- Quality control of manganese ore and concentrate production to verify arsenic levels are within contractual or regulatory limits.
- Regulatory compliance testing where arsenic reporting is required for mineral shipments or environmental reporting.
- Laboratory standardization: Provides a reproducible comparison method (using prepared comparison solutions) for routine arsenic determination and inter-laboratory consistency.
Related Standards
- ISO 4297 – Manganese ores and concentrates: methods of chemical analysis (general instructions).
- ISO 4296-1 / ISO 4296-2 – Sampling and preparation of manganese ores (increment sampling and sample preparation).
Practical value: ISO 317:1984 offers a detailed, validated workflow - reagents, apparatus, sample prep, distillation, colour development and spectrometric measurement - enabling laboratories to obtain precise and reproducible arsenic determinations in manganese materials for QC and compliance purposes.
Open preview (PDF)Manganese ores and concentrates — Determination of arsenic content — Spectrometric method