Pre-concentration of environmental tin and its determination using catechol violet

Abstract

Inorganic tin in natural waters can be quantitatively absorbed and preconcentrated by polyurethane foam soaked in toluene-3,4-dithiol. Interfering substances can be removed by converting tin into tin(IV) iodide and extracting this species into toluene. Tin can be determined as its complex with catechol violet and cetyltrimethylammonium bromide, which absorbs at 650 nm. A method of separating tin(II) from tin(IV) using polyurethane foam and diethylammonium diethyldithiocarbamate has been devised for pure water but is less successful for natural waters. The spectrophotometric method has been tested on eight geological and four biological reference materials, and the pre-concentration method has been used to measure tin in lake water.