This part of ISO21068 gives definitions and specifies techniques for the preparation of samples for the chemical analysis of silicon-carbide-containing raw materials and refractory products including: graphite brick containing silicon carbide; silicon carbide brick (includes the bricks containing silicon nitride); refractories containing carbon and/or silicon carbide mixed with clay; refractories containing carbon and/or silicon carbide mixed with silica (and fused silica); refractories containing carbon and/or silicon carbide mixed with high alumina material; refractories containing carbon and/or silicon carbide mixed with magnesia (and dolomite); refractories containing carbon and/or silicon carbide mixed with chrome mineral or magnesia-chrome materials; refractories containing carbon and/or silicon carbide except those described in a) to g) above. The items of chemical analysis described in ISO21068, Parts 1 to 3 are as follows: loss on drying (LOD); loss on ignition (LOI); total carbon, Ctotal; free carbon, Cfree; silicon carbide, SiC; free silicon (Sifree); free aluminium (Alfree); free magnesium (Mgfree); free iron (Fefree); silicon(IV) oxide (SiO2); aluminium oxide (Al2O3); iron(III) oxide (total iron oxide calculated as Fe2O3); titanium(IV) oxide (TiO2); calcium oxide (CaO); magnesium oxide (MgO); sodium oxide (Na2O); potassium oxide (K2O); chromium(III) oxide (Cr2O3); zirconium oxide (ZrO2); boron oxide (total boron calculated as B2O3); nitrogen; oxygen; nitrides (undifferentiated: Si3N4, AlN, BN, sialon, oxy-nitrides, etc.). The range of determination specified in this part of ISO21068 is given in Table1. Table1 Range of determination Component Range %by mass LOI –10 to 99 Ctotal 0,01 to 99 Cfree 0,01 to 99 SiC 3 to 99 Sifree 0,1 to 10 Alfree 0,1 to 10 Mgfree 0,1 to 10 Fefree 0,1 to 10 SiO2 0,1 to 95 Al2O3 0,1 to 95 Fe2O3 0,1 to 15 TiO2 0,1 to 5 CaO 0,1 to 60 MgO 0,1 to 95 Na2O 0,1 to 5 K2O 0,1 to 5 Cr2O3 0,1 to 40 ZrO2 0,1 to 1 B2O3 0,1 to 5 Si3N4 0,1 to 35