Semi-Quantitative “Spot-test” of Cyanide

Abstract

A selective, sensitive, rapid and simple-handling analytical method for the determination of cyanide at low detection limits in surface and underground water, soil and industrial waste samples was developed. The method is based on a reaction, proposed by Guilbault and Kramer, where free cyanide reacts with p-nitrobenzaldehyde to form an intermediate cyanohydrin, which reacts with o-dinitrobenzene to give a highly colored purple compound. The original procedure was modified for application in a small device containing a gas-permeable membrane. The cyanide is converted in the volatile hydrogen cyanide, which permeates through a PTFE membrane, reaching colorimetric reagents. In order to obtain semi-quantitative results, printed color scales were built. The method allows rapid, accurate, selective, low-cost and simple-handling determinations of free cyanide, even in complex samples. About 150 real samples were analyzed. Less than 10 ng of free cyanide per ml (10 µg l -1 ) can be easily detected. For more concentrated solutions, the results had been compared to those obtained using differential pulse polarography. The standard addition method was used for more diluted solutions.

Rapid colorimetric field test to determine levels of deltamethrin on PermaNet® surfaces: association with mosquito bioactivity

“…This highly sensitive colorimetric assay can detect residual deltamethrin adhered onto filter paper after exposure to impregnated net material. This reaction has been used to detect cyanide in blood, water, soil and industrial waste (Vesey et al 1999;Favero & Tubino 2003). So far, the test has been demonstrated in our lab to work with deltamethrin, k-cyhalothrin, and a-cypermethrin.…”

A Study on Ninhydrin Reaction with Weak Acid Dissociable Cyanide and Its Application for Toxic Cyanide Determination

“…From the analytical point of view, the ninhydrin reaction with cyanide being very sensitive, fast, selective and with non-toxic reagents, is appropriate for implementation for sensitive WAD cyanide determination by spectrophotometry. Recently, the research interest have been directed to WAD quantification and a line of methods were developed based on different approaches for cyanide liberation and separation: ligand exchange, HCN formation in acidic solutions and gas-diffusion separation [8,[11][12][13][14] or head-space extraction [10,15]; ligand exchange combined standard distillation procedure [10], chromatographic or capillary electrophoresis [15] techniques.…”

The use of tristimulus colorimetry for the determination of hydrogen cyanide in air by a modified König method

“…4 This König reaction was employed for HCN detection in air in numerous modifications, e.g., for sensitive detection crayons 5 or tubes. 6 Other methods are based on the reaction of HCN with Cu 2+ and aromatic amines, 7 sodium picrate, 8 p-nitrobenzaldehyde, 9 ninhydrin, 10 aromatic disulphides, 11 and on other reactions.…”