Determination of cyanides

Discussion. The theory of the titration of cyanides with silver nitrate solution has been given in Section 10.44. All silver salts except the sulphide are readily soluble in excess of a solution of an alkali cyanide, hence chloride, bromide, and iodide do not interfere. The only difficulty in obtaining a sharp end point lies in the fact that silver cyanide is often precipitated in a curdy form which does not readily re-dissolve, and, moreover, the end point is not easy to detect with accuracy. 

There are two methods for overcoming these disadvantages. In the first the precipitation of silver cyanoargentate at the end point can be avoided by the addition of ammonia solution, in which it is readily soluble, and if a little potassium iodide solution is added before the titration is commenced, sparingly soluble silver iodide, which is insoluble in ammonia solution, will be precipitated at the end point. The precipitation is best seen by viewing against a black background. 

In the second method diphenylcarbazide is employed as an adsorption indicator. The end-point is marked by the pink colour becoming pale violet (almost colourless) on the colloidal precipitate in dilute solution (ca 0.01 M) before the opalescence is visible. In 0.1M solutions, the colour change is observed on the precipitated particles of silver cyanoargentate. 

Procedure. NOTE Potassium cyanide and all other cyanides are deadly poisons, and extreme care must be taken in their use. Details for the disposal of cyanides and other dangerous and toxic chemicals may be found in Refs 14 and 15. 

For practice in the method, the cyanide content of potassium cyanide (laboratory reagent grade) may be determined. 

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Cyanide in Waters etc. (by Reflux Distillation followed by either Potentiometry using a Cyanide Selective Electrode or Colorimetry, or Continuous Elow Determination of Cyanide or Determination by Microdiffusion), 1988... 

Note. Great care must be taken in the use and determination of cyanides owing to their highly poisonous nature. 

Brimer, L. 1988. Determination of cyanide and cyanogenic compounds in biological systems. Pages 177-200 in D. Evered and S. Harnett (eds.). Cyanide compounds in biology. Ciba Foundation Symposium 140. John Wiley, Chichester. 

Nonomura, M. and T. Hobo. 1989. Ion chromatographic determination of cyanide compounds by chloramine-T and conductivity measurement. Jour. Chromatogr. 465 395-401. 

Look up the titrimetric method for the determination of cyanide and describe it. 

Chen S-H, Wu S-M, Kou H-S, et al. 1994. Electron-capture gas chromatographic determination of cyanide, iodide, nitrite, sulfide and thiocyanate anions by phase-transfer-catalyzed derivatization with pentafluorobenzyl bromide. J Anal Toxicol 18(2) 81-85. 

Egekeze JO, Oehme FW. 1979. Direct potentiometric method for the determination of cyanide in biological materials. J Anal Toxicol 3 119-124. 

Feldstein M, Klendshoj NC. 1954. The determination of cyanide in biologic fluids by microdiffusion analysis. J Lab Clin Med 44 166-170. 

Fogg AG, Alonso RM. 1987. Oxidative amperometric flow injection determination of cyanide at an electrochemically pre-treated glassy carbon electrode. Analyst 112 1071-1072. 

Gamoh K, Imamichi S. 1991. Postcolumn liquid chromatographic method for the determination of cyanide with fluorimetric detection. Anal Chim Acta 251(102) 255-259. 

Ganjeloo A, Isom GE, Morgan RL, et al. 1980. Fluorometric determination of cyanide in biological fluids with p-benzoquinone. Toxicol Appl Pharm 55 103-107. 

Honig DH, Hockridge ME, Gould RM, et al. 1983. Determination of cyanide in soybeans and soybean products. J Agric Food Chem 31 272-275. 

Ma H, Liu J. 1992. Flow-injection determination of cyanide by detecting an intermediate of the pyridine-barbituric acid chromogenic reaction. Anal Chim Acta 261(l-2) 247-252. 

Madungwe L, Zaranyika MF, Gurira RC. 1991. Reversed-phase liquid chromatographic determination of cyanide as 1-benzoyl-1,2-dihydroquinaldonitrile. Analytica Chimica Acta 251 109-114. 

Mlingi N,Vassey VD, Swai A BM, et al. 1993. Determinants of cyanide exposure from cassava in a konzo-affected population in northern Tanzania. Int J Food Sci Nutr 44(2) 137-144. 

Nikolic SD, Millosavljevic EB, Nelson JH. 1992. Flow injection amperometric determination of cyanide on a modified silver electrode. Analyst (London) 117(l) 47-50. 

Nonomura M. 1987. Indirect determination of cyanide compounds by ion chromatography with conductivity measurement. Anal Chem 59 2073-2076. 

Odoul M, Fouillet B, Nouri B, et al. 1994. Specific determination of cyanide in blood by headspace gas chromatography. J Anal Toxicol 18(4) 205-207. 

Rocklin RD, Johnson DL. 1983. Determination of cyanide, sulfide, iodide, and bromide by ion chromatography with electrochemical detection. Anal Chem 55 4-7. 

Rubio R, Sanz J, Rauret G. 1987. Determination of cyanide using a microdiffusion technique and potentiometric measurement. Analyst 112 1705-1708. 

Sano A, Takezawa M, Takitani S. 1989. Spectrofluorometric determination of cyanide in blood and urine with naphthalene-2,3-dialdehyde and taurine. Anal Chim Acta 225 351-358. 

Sano A, Takimoto N, Takitani S. 1992. High-performance liquid chromatographic determination of cyanide in human red blood cells by pre-column fluorescence derivitization. J Chromatogr 582 131-135. 

Toida T, Togawa T, Tanabe S, et al. 1984. Determination of cyanide and thiocyanate in blood plasma and red cells by high-performance liquid chromatography with fluorometric detection. J Chromatogr 308 133-141. 

Tomoda A, Hashimoto K. 1991. The determination of cyanide i water and biological tissues by methemoglobin. J Hazardous Materials 28 241-249. 

Tomoda A, Nagai K, Hashimoto K. 1992. A simple and convenient method for the determination of cyanide in bloods and water by methemoglobin. Int Congr Ser - Excerpta Med 991 (Progress in Clinical Biochemistry) 789-791. 

Westley AM, Westley J. 1989. Voltammetric determination of cyanide and thiocyanate in small biological samples. Anal Biochem 181 190-194. 

Cyanide ion-selective electrode As demonstrated in chapter 3.4, the dissolution of a halide ISE in the presence of some complexing agents, especially cyanide, can be used for determination of these agents [312, 392, 434]. An iodide ISE can be used as a cyanide ISE. The principal application of this electrode is in the determination of cyanides in waters [60, 126, 281, 336] and in galvanic baths [222, 225]. 

A flow-through electrode has also been constructed for the determination of cyanide [282]. In some media it is preferable to first separate cyanide by distil-... 

The monitoring of cyanide with microbial sensor is possible in two ways. The first principle is based on the inhibition of respiration of Saccharomyces cervisiae by cyanide [102, 103]. This sensor showed a linear response in the range 0-15 pmol 1 by a response time of approximately 10 min and a stability of 9 days. Another method for the determination of cyanide is enabled by the use of cyanide-degrading microorganisms such as Pseudomonas fluorescens [1041. This bacterium specifically oxidizes cyanide by consuming oxygen ... 

Lee JM, Karube I (1995) A novel microbial sensor for the determination of cyanide. Anal Chim Acta 313 69-74... 

Vanadium(II) reacted with SCN- and diphenylguanidine (L) to form a ternary complex with a V SCN L ratio of 1 2 2.176 Other ternary complexes like phenylguanidine iron(II) cyanide are being exploited in titrimetric determination of cyanide ions, for example. 

Tecator [14] produced apparatus based on distillation and titration or spectrophotometry for the determination of cyanide in soil. 

Harris et al. [8] has described methods for the determination of cyanide in these materials based on either spectrophotometry using p-phenylene diamine pyridine or gas chromatographically following conversion of cyanide to cyanogen bromide. Cyanide is extracted from the sample by digestion with phosphoric acid. Recoveries were in the range 96-99% (spectrophotometric method) and 90-96% (gas chromatographic method). 

Chadha, R.K., Lawrence, J.F., and Ratnayake, W.M.N. 1995. Ion chromatographic determination of cyanide released from flaxseed under autohydrolysis conditions. Food Add. Cont. 12, 527-533. 

The above procedure is similar to the analysis of total cyanide in the alkaline distillate described in the preceding section, except that the sample pH are different. In the above method, chlorination is done on the alkaline sample at a pH between 11.5 and 12. On the other hand, in the determination of cyanide (total), the pH of the distillate is maintained below 8 with acetate buffer before adding chloramine-T solution. 

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