Spectrophotometric determination of tin in steel with dibromo-hydroxyphenylfluorone

In the presence of emulsifier OP and 0.4-0.6mol/L H 2SO 4 medium,tin reacts with bromo-hydroxyphenylfluorone to form a stable colored complex with molar ratio of 1∶3,which has a maximum absorption at 510-515nm Its apparent molar absorption coefficient is 1 2× 10 5 L·mol -1 ·cm -1 Beer’s law is obeyed in the range of 0-0 4μg/mL Iron and copper do not interfere in the determination of tin, only molybdenum,titanium and tungsten do The interference of molybdenum can be eliminated with hydroxylamine hydrochoride The influences of titanium and tungsten can be ignored for their trace contents in carbon steel and low-alloy steel The drafted method has been applied to the determination of molybdenum in steel with satisfactory results