Study on the color reaction of 2-hydroxy-3-methoxyphenylfluorone with tin and its application

A new method has been developed for spectrophotometric determination of tin in pure copper with 2-hydroxy-3-methoxyphenylfluorone(abb. HMPF). In the medium of H_2SO_4 and in the presence of CTMAB, HMPF reacts with tin to form a 1:3 red complex with a maximum absorption peak at 523.5nm.Under room temperature,the reaction is completed instantaneously and the complex can be stable for 24h at least.Its apparent molar absorptivity is 1.25×10~5L·mol~(-1)·cm~(-1),Beer's law is obeyed in the range of 0-30μg for Sn? in 25mL solution.Moreover,the color system also has excellent selectivity,most of metal ions can be tolerated in considerable amounts,especially transition metal.Proposed method has been applied to determine trace tin in pure copper directly with satisfactory results.