UNE 55539-4
SURFACE ACTIVE AGENTS. METHODS FOR PREPARATION, STANDARDIZATION AND STORAGE OF STANDARD SOLUTIONS TO BE USED IN VOLUMETRIC ANALYSIS OF SURFACE ACTIVE AGENTS AND FORMULATIONS CONTAINING THEM. PART 4: SOLUTIONS OF SULFURIC ACID, OF CONCENTRATIONS BETWEEN 0,01 MOL/L AND 0,5 MOL/L.