Colorimetric detection of cyanide ions using complex formation and ctab-coated silica

Abstract

This research presents a new colorimetric method of cyanide detection in solution and water samples based on the extraction of dicyano-bis-(1,10-phenanthroline)-iron(II) complex onto CTAB-coated silica. The complex was formed at pH 10 by using phosphate buffer via the complex formation between tris-(1,10-phenanthroline)-Iron(II) (ferroin) with cyanide ions in CTAB media. When the complex was extracted onto CTAB-coated silica, it resulted in a color change of the material from pale yellow to purple. The changing of color corresponded to cyanide concentration which could be observed by naked-eyes and the color intensity was determined by Image J. The effects of various parameters were investigated including ferroin concentration used to form complex, sample volume, CTAB concentration in complex formation step, extraction time and ferroin concentration used to form complex in CTAB media. Moreover, the effect of water sample matrix and foreign anions were also studied. This method had a linear range from 30-150 mM and limit of detection (S/N=3) of 17.2 mM. The recovery of cyanide in sample observed by the proposed method was 83.00-99.49% and standard deviation was 1.23-7.14%. This method was applied to determine cyanide in water samples with acceptable accuracy and precision.