SPECTROPHOTOMETRIC DETERMINATION OF NANOGRAM AMOUNTS OF TIN AFTER EXTRACTION FROM IODIDE MEDIA

A spectrophotometric method for the determination of trace amounts of tin is described. Tip was selectively extracted as SnI4 into benzene and stripped into water. The stripping was treated with bromine water and the resulting iodate was treated with iodide to liberate iodine. The iodine was extracted into benzene and equilibrated with iodate in the presence of excess chloride and acid to produce ICI2- which was reextracted into benzene as ionpair with rhodamine 6G. Measurement of the benzene extract at 535 nm permitted the determination of tin when present in the concentration range 4-200 ng. The molar absorption coefficient was found to be 1.54x10(6) dm(3) mol(-1) cm(-1) and the color system is stable for I h. The relative standard deviation for ten determinations of 100 ng of tin was found to be 2.1%. The efficiency of the reaction sequence was found to be 96.2%. The method was found useful for the precise determination of tin in steel and alloy samples.