Spectrophotometric determination of iron in complex high sensitive system of Fe~(3+)-SCN~-—Rhodamine B with PVA and gelatin cooperation

A new high sensitive spectrophotometric method was developed for determination trace iron.The method was based on the reaction of Fe(III) with SCN(I) and Rhodamine B,which forms a stable blue ternary ion complex system in sulfuric acid medium in the presence of polyvinyl alcohol and gelatin.The most absorption wavelength for 620 nm,the linear regression equation is y=0.924x+0.281 3,the correlation coefficient is 0.999 4,and apparent molar absorptivity is 3.38×106 L·(mol·cm)-1,with detection limit of 0.025 μg/L,the linear range was 0 ~0.8 μg/25 mL,this method is high sensitivity,selectivity and simplicity.Samples of mineral water,grape wine and beer were analyzed by this method for their Fe(Ⅲ) contents.The results obtained were in conformity with the results found by FAAS,the relative standard deviations(RSD)of determinations were 1.3%~3.1% and recoveries were 98%~101%.