This International Standard specifies an instrumental method for the determination of specific surface area (SSA) of smelter-grade alumina (SGA) by nitrogen adsorption by a single- or multi-point method. A multi-point method is recommended due to the higher accuracy obtained; if a single-point method is used, a lower result will be obtained. NOTE Annex A provides an explanation of the difference between single- and multi-point determined BET SSA. This International Standard is applicable to aluminas having a surface area between 50 m/g and 90 m/g.