Abstract − Analytical Sciences, 19(8), 1139 (2003).
Semi-Quantitative“Spot-test” of Cyanide
José Arnaldo Dibbern FÁVERO andMatthieu TUBINO
Instituto de Química, UniversidadeEstadual de Campinas, CP 6154, 13084-971 Campinas, SP, Brazil
A selective, sensitive, rapid andsimple-handling analytical method for the determination of cyanide at lowdetection limits in surface and underground water, soil and industrialwaste samples was developed. The method is based on a reaction, proposedby Guilbault and Kramer, where free cyanide reacts withp-nitrobenzaldehyde to form an intermediate cyanohydrin, whichreacts with o-dinitrobenzene to give a highly colored purplecompound. The original procedure was modified for application in a smalldevice containing a gas-permeable membrane. The cyanide is converted inthe volatile hydrogen cyanide, which permeates through a PTFE membrane,reaching colorimetric reagents. In order to obtain semi-quantitativeresults, printed color scales were built. The method allows rapid,accurate, selective, low-cost and simple-handling determinations of freecyanide, even in complex samples. About 150 real samples were analyzed.Less than 10 ng of free cyanide per ml (10 µg l-1) can beeasily detected. For more concentrated solutions, the results had beencompared to those obtained using differential pulse polarography. Thestandard addition method was used for more diluted solutions.
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