Cyanide ion selective electrode

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]. 

Elemental composition H 3.73%, C 44.44%, N 51.83%. HCN may be analyzed by GC or GC/MS. The aqueous solution may be directly injected onto the GC column and determined by an FID. For GC/MS determination, an alcoholic solution may be injected into the column. The characteristic mass ions are 27 and 26. The cyanide ion in aqueous solution also may be measured by cyanide ion-selective electrode, titrimetry, and by colorimetric methods (APHA, AWWA, WEF. 1999. Standard Methods for the Examination of Water and Wastewater, 20th ed. Washington, DC American Public Health Association). For colorimetric analysis, the aqueous solution may be treated with a dilute caustic soda solution, followed by treatment with chloramine-T, and then with pyridine-barbituric acid reagent. A red-blue color develops, the absorbance of which is measured by spectrophotometer at 578 nm. The concentration of CN is determined from a standard cahbration curve using KCN standards. 

Elemental composition K 60.05%, C 18.44%, N 21.51%. An aqueous solution of the salt is analyzed for potassium (see Potassium) and for CN by a cyanide ion-selective electrode. The solution must be diluted appropriately for measurement. Alternatively, CN may be titrated by the pyridine-barbituric acid colorimetric method (see Hydrogen Cyanide.)... 

Air drawn through a 0.8-mm cellulose ester membrane (to separate cyanogen from particulate cyanide) followed by 0.1 N KOI I bubbler soln. cyanide ion analyzed by cyanide ion-selective electrode recommended flow rate 200 mL/min sample volume 10 L. 

The potentiometric determination of cyanide using ion selective electrodes has become yet another very popular technique, because it is convenient, rapid, and sensitive method of analysis (Frant et al, 1972). Microdiffusion of biological samples containing cyanide is recommended prior to potentiometric determination. The use of a cyanide ion-selective electrode in combination with the Conway microdiffusion method for the measurement of cyanide concentrations in human red blood cells and plasma was reported with remarkable recovery of cyanide (Yagi et al, 1990). Ion chromatographic determination of sulfide and cyanide in real matrices by using pulsed amperometric detection on a silver electrode was reported by Giuriati et al. (2004). 

Vickroy, D.G. and G.L. Gaunt Jr Determination of cyanide in cigarette smoke by a cyanide ion selective electrode 25th Tobacco Chemists Research Conference, Program Booklet and Abstracts, Vol. 25, Paper No. 25, 1971, p. 15 Tob. Sci. 16 (1972) 22-25. 

The quantitative reduction, or photodecomposition by illumination with a powerful light source, of cyanocobalamin liberates hydrogen cyanide, and this may be used to precede the assay stage in pharmaceutical preparations [406] with a cyanide ion-selective electrode at pH 11. 

Ion-selective electrodes Ion-selective electrodes function as a half-cell that in the presence of certain ions produces an electrical potential that can be compared to a reference cell. The selectivity is determined by the nature of the membrane separating the electrode from the test solution. Membranes used in cyanide ion-selective electrodes are usually of the... 

Cyanide compounds are classified as either simple or complex. It is usually necessary to decompose complex cyanides by an acid reflux. The cyanide is then distilled into sodium hydroxide to remove compounds that would interfere in analysis. Extreme care should be taken during the distillation as toxic hydrogen cyanide is generated. The cyanide in the alkaline distillate can then be measured potentiometricaHy with an ion-selective electrode. Alternatively, the cyanide can be determined colorimetricaHy. It is converted to cyanogen chloride by reaction with chloramine-T at pH <8. The CNCl then reacts with a pyridine barbituric acid reagent to form a red-blue dye. 

Both of these haUdes can also be determined potentiometricaHy with an appropriate ion-selective electrode. Sulfide and cyanide both interfere with the electrode response. 

Hydrogen cyanide in air Lab method using an ion-selective electrode 5612... 

Tecator FIA star 5025 Relatively low cost manual instrument specifically designed for fluoride, cyanide, potassium, iodide, etc. Specially designed for use with ion-selective electrodes... 

NH4CN may be analyzed by heating the salt and trapping the decomposed products HCN and ammonia in water at low temperatures. The aqueous solution is analyzed for cyanide ion by silver nitrate titrimetric method or an ion-selective electrode method and ammonia is measured by titration or electrode technique (Patnaik, P. 1997. Handbook of Environmental Analysis, Boca Raton, FL Lewis Publishers). 

To 1 g sample, add 100 mL of 10% caustic soda solution and stir for 12 h. (This treatment is required only if iron cyanides are suspected to be present in the sample.) After this, adjust the pH to less than 8.0 with 1 1 H2S04. Add about 0.2 g sulfamic acid to avoid nitrate/nitrite interference. This is followed by addition of 25 mg lead carbonate (to prevent interference from sulfur compounds). The mixture is distilled and collected over NaOH solution. This distillate is analyzed for CN by colorimetric, titrimetric, or ion-selective electrode method. 

Distill this chlorine treated sample aliquot for cyanide analysis using colorimetric, titrimetric, or ion-selective electrode method outlined in the preceding sections. 

Aqueous samples distilled directly without any acid treatment HCN liberated and collected in NaOH solution cyanide analyzed by colorimetric or by ion selective electrode method (See Cyanide, Chapter 2.6). 

Numerous methods have been reported for the analysis of cyanide and thiocyanate in biomedical samples, mostly for the determination of cyanide levels in smokers and fire victims rather than cases of deliberate poisoning. These methods include visible, ultraviolet (UV) and fluorescence based spectrometric methods, electrochemical methods using ion selective electrodes, and GC with nitrogen-phosphorus detection (NPD), electron capture detection (ECD), or MS. It is not intended to cover all of these but focus mainly on chromatographic methods. 

The measurement of non-metal inorganic contaminants, such as cyanide and sulfate, is dependent on wet chemistry techniques, albeit usually automated and with final determination using spectroscopy, ion chromatography or ion-selective electrodes. 

H. Muller, Chloride and cyanide determination by use of the flow injection method using ion-selective flow-type electrodes, 3rd Symposium on ion-selective electrodes, Matrafiired, 279 (1980). 

Reif, H. The use of the ion-selective electrode for cyanide determination in cigarette smoke Fachliche Mitt. 

Cyanides can also be determined by membrane ion-selective electrodes using direct potentiometry (argentoiodide electrode or an electrode with a mixture of Agl-AgjS). The principle of the response to cyanides in the case of the most frequently used ion-selective electrodes for CN ions consists in the dissolution of Agl according to the following reaction ... 

I recollect very elegant research starting fixtm Prof. G. Rechnitz involving the development of an amygdaline sensor based on the coupling of an Ion Selective Electrode (cyanide ISE) tvith betaglucosidase to give benzaldeyde and cyanide. ... 

Given the vride variety of ion-selective electrodes already commercially available and the many more specialized ones that can be fabricated, titrations involving the precipitation or complexation of ions are widely used. Halides, cyanide, thiocyanate, sulfide, chromate, and thiols can be titrated with silver nitrate, using the appropriate... 

Tatsuta, H., T. Nakamura, and T. Hinoue (2001). Thermal modulation voltammetric observation of cyanide ion in the membrane part of an ion-selective electrode based on a polymer modified with cobalt phthalocyanine in acetonitrile. Anal. Sci. 17, 991-994. 

Cyanide Flow injection, ion-selective electrode, titrimetry, ion chromatography... 

Bromide, iodide, cyanide, and especially, sulfide ions strongly interfere with the potentiometric determination of chloride ions. Fortunately, these ions are seldom present in disturbing concentration in certain water samples. The solid-state ion-selective electrodes are not sensitive to oxidizing agents however, their function is influenced by strong reducing agents. 

The application of direct potentiometry with silver bromide precipitate-based ion-selective electrodes for bromide measurements in water samples as been investigated [65]. Cyanide, sulfide, and iodide ions represent the major interferences. A 20 times higher concentration of chloride also can cause positive error. TTierefore, the applicability of direct potentiometry in the analysis of bromide concentration of water samples is limited. 

An automated system for potentiometric determination of free and total cyanide in wastewaters is by employing a homogeneous membrane tubular ion-selective electrode [38]. After the electrode is assembled, it is connected to a system composed of 3 three-way solenoid valves, sample line, carrier line, acid stream, and gas diffusion chamber. A turbo pascal computer program performs all the steps involved in data acquisition and processing. The proposed analytical procedure offers operational simplicity, since detection is performed by a cyanide ion-selective tubular electrode, and is fast and easy to assemble. 

A monitor was described for the determination of free cyanide in river water and is based upon a silver ion-selective electrode (Ag/Ag+) [57]. The determination of cyanide relies on the formation of the very stable Ag(CN)2 complex and the potential for a silver ion is changed when the cyanide is added to solution. 

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