GB/T 5686.4-2008 gives the molybdenum blue photometric method and the alkali content Titrimetric method for the determination of phosphorus content of ferromanganese and other materials. The molybdenum blue photometric method is quantified by phosphorus-molybdenum blue chromogenic measurement. The alkali content Titrimetric method is calculated according to acid-base reaction titration. This standard is applicable to ferromanganese, manganese-silicon alloy and other products. Clarify the requirements of spectrophotometer, Burette and other instruments, and specify the preparation of reagents. Detail Sample Handling, including acid dissolution, oxidation and other steps. Standardize the operation of two methods, such as color conditions in photometry and Titrimetric method titration process control. According to this standard, phosphorus content can be accurately measured, providing key data for product mass evaluation and steel smelting process adjustment.