High purity chromium metal, crushed to a nominal particle size of less than 1700 µm. It is supplied in bottles of 100g of material to a nominal grading of 1700 – 250µm (10 – 60 mesh). 4004 Page 2 of 2 BCS-CRM 361 CHROMIUM METAL NOTES ON METHODS USED CARBON All Analysts, except No. 3, determined carbon by high frequency combustion- infrared absorption. Analyst No 3 used non-aqueous titration according to the Standard Method BS 6200:3.8.2:1991. SILICON Analysts Nos. 3, 5 and 9 determined silicon gravimetrically after dehydration with perchloric acid. The other Analysts determined silicon using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). SULPHUR All Analysts, except No 3, determined sulphur by high frequency combustion-infrared absorption. Analyst No 3 determined sulphur photometrically as methylene blue after separation as H2S in a manner similar to the Standard Method ISO 10701. NITROGEN All Analysts, except Nos. 1 and 3, determined nitrogen using thermal conductivity after decomposition in a graphite crucible. Analysts Nos. 1 and 3 used an acidimetric titration after distillation according to the Standard Method BS 6200:3.22.1: 1992. IRON Analysts Nos.3, 5 and 9 determined iron using Flame Atomic Absorption Spectrometry (FAAS). Analysts Nos. 6, 7 and 8 used ICP- OES. OXYGEN All Analysts determined oxygen after combustion in a graphite furnace in an inert atmosphere. ALUMINIUM (TOTAL) All Analysts except No.9 determined aluminium by ICP-OES after fusion of the insoluble residue. Analyst No. 9 determined aluminium by FAAS. Analysts Nos. 3 and 8 fused the insoluble residue with potassium hydrogen sulphate, No. 6 with sodium peroxide, No. 7 with a mixture of sodium peroxide and sodium carbonate and No.9 an equimolar mixture of sodium carbonate and potassium carbonate with boric acid.

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