Determination of Cyanide at Trace Levels by Computational Scanning Densitometry

Abstract

Introduction: Cyanide is one of the most commonly present anions in industrial effluents, highly toxic to human and animal life. Therefore, its determination in aqueous media by simple, portable, and quick methods is required. Objective: This study aims to develop a simple and quick method to determine this anion at the micro level in aqueous media without using any expensive instrument. Method: The method is based on treating the microliter sample of aqueous cyanide with the classical Lassaigne’s reagents on a TLC plate. After heating in an oven for a few minutes, a deep blue spot of ferric ferrocyanide complex appeared on the plate. The color depth of the spots was measured by scanning the TLC plate and analyzing the image with an indigenous software package. Result: As a result of fusion with metallic sodium, carbon and nitrogen of the organic compound combine to form cyanide, which first reacts with Fe(II) to form hexacyanoferrate ion [Fe(CN)6]4- that further combines with Fe(III) to create a neutral deep blue colored coordination complex, ferric ferrocyanide Fe4[Fe(CN)6]3. Discussion: This process converts real-world colors into numeric computer data consisting of rows and columns of pixels. Each pixel will consist of three numeric components, i.e., red, green, and blue. The pixel's color will be one of 16.8 million possible color combinations (256 shades of red, green, and blue each). Conclusion: From the comparison of results obtained by the proposed method and standard ion-selective electrode method, it can be concluded that the former method for determining micro quantities of cyanide in aqueous samples using computational densitometry is a simple, accurate, and adequately precise method without the involvement of sophisticated instrumentation.