A rapid method for the colorimetric determination of tin in canned soft drinks was developed. It was possible to carry out the determination without digestion, even of colored samples, prior to analysis. The pretreatment involved extraction with methyl iso-butyl ketone (MIBK) from a solution of the sample in about 7N hydrochloric acid. The MIBK extract obtained here was further extracted with distilled water. The amount of tin (Sn4+) in this water layer was colorimetrically determined at 560nm by means of the hematein method reported previously. Using the method described above, it was found that tin content in nine kinds of soft drinks could be determined with recovery of 90.9-107.8% and coefficient of variation of 0.9-3.7%.
This rapid method is useful for tin determination in canned soft drinks at laboratories and factories where a large number of samples must be analyzed.