Specific ion electrode

M.p. 296 C. Accepts an electron from suitable donors forming a radical anion. Used for colorimetric determination of free radical precursors, replacement of Mn02 in aluminium solid electrolytic capacitors, construction of heat-sensitive resistors and ion-specific electrodes and for inducing radical polymerizations. The charge transfer complexes it forms with certain donors behave electrically like metals with anisotropic conductivity. Like tetracyanoethylene it belongs to a class of compounds called rr-acids. tetracyclines An important group of antibiotics isolated from Streptomyces spp., having structures based on a naphthacene skeleton. Tetracycline, the parent compound, has the structure ... 

Ion-specific electrodes can be used for the quantitative determination of perchlorates in the parts per million (ppm) range (109) (see Electro ANALYTICAL techniques). This method is linear over small ranges of concentration, and is best appHed in analyzing solutions where interferences from other ionic species do not occur. 

ELECTRODEjcls Fig. 4.24 The operation of an ion-specific electrode with a slope of 59.16 mV per decade for mono-valent ions (29.58 mV/dec for di-valent ions) is simulated under the assumption that a digital volt meter with a resolution of, say, 0.1 mV is used. The sample volume and the concentration of the metered titration solution are known. Normally, one would add a few milliliters of the concentrated titration solution and do the calculation spelled out in lines 140-150 in Table 4.22 here, because the sample concentration is known, the result can be normalized to it. The operation of short-cuts (volume correction), unknowns (volume bias, deviation of true slope from theoretical), and equipment shortcomings (digitization) can be studied. 

Frant, M. S. and Ross, J. W., Jr. Potassium ion specific electrode with high selectivity for potassiim over sodiim. Science (1970), 167> 987 - 988. 

Such a result may be put in parallel with the determination of the bound cations obtained by ion-specific electrode or dual-wavelength spectrophotometric method, and analysed in terms of cooperativity [7,29,31]. 

In the Antek Fluoride Analyzer, a pyrolysis furnace is combined with an ion-specific electrode cell (ISE). Table 8.9 compares this specific analyser to a conventional combustion bomb. 

ISEs were originally and sometimes still are called ion-specific electrodes, and this term may still be encountered. 

Because of the complex nature of soil and soil solutions, it is rarely possible to directly determine specific soil constituents by titrating soil or soil solutions using a pH meter, ion-specific electrode, or a platinum electrode (with appropriate reference electrode) [3],... 

An appropriate ion-specific electrode was found to provide a convenient, precise and relatively inexpensive method for potentiometry of copper(II) ion in copper-complex azo or formazan dyes. Copper(II) ion in copper phthalocyanine dyes can be quantified after anion exchange. Twelve commercial premetallised dyes evaluated using this technique contained copper(II) ion concentrations in the range 0.007 to 0.2%. Thus many copper-complex direct or reactive dyes are likely to contribute low but possibly significant amounts of ionic copper to textile dyeing effluents [52]. 

Reversible cell potentials have been the source of much thermodynamic data on aqueous electrolytes. In recent years, this technique has been extended to nonaqueous solutions and to molten salt systems. Its use for aqueous solutions, relative to other techniques, has decreased. Various ion specific electrodes have been developed in recent years. These are used primarily in analytical chemistry and have not produced much thermodynamic data. 

Development of lithium selective electrodes (LiSE) and their application in clinical chemistry have been amply reviewed Several models of lithium ion specific electrodes are commercially available. The central problems in developing such sensing devices are their dynamic range, the accuracy and precision by which the signals are correlated to the concentration of the analyte and the selectivity towards that species, especially in relation to other alkali metal cations. Additional problems of practical importance are the times of response and recovery and the durability of the electrode in the intended service. 

Elemental composition F 51.30%, H 10.88%, N 37.82%. A measured amount is dissolved in water and the aqueous solution diluted appropriately and analyzed for fluoride by fluoride ion-selective electrode, or by ion chromatography. Ammonium ion (or hberated ammonia) is analyzed by titration or by ammonium ion-specific electrode (see Ammonia). 

Elemental composition H 4.11%, Mo 48.94%, N 14.29% O 32.65. (NH4)2Mo04 is digested with nitric acid and the molybdenum metal is analyzed by atomic absorption or emission spectrophotometry. It is dissociated to ammonia, which may be measured by titration or by an ion-specific electrode technique (see Ammonia). Ammonium molybdate reacts under acid conditions with dilute orthophosphate solution to form molybdophosphoric acid which, in the presence of vanadium, forms yellow vanadomolybdophosphoric acid the intensity of the yeUow color may be measured by a spectrophotometer at 400 to 490 nm and is proportional to the trace amount of ammonium molybdate. 

Elemental composition H 5.44%, N 18.90%, 0 32.39%, S 43.27%. It is dissolved in water and the aqueous solution may be analyzed for thiosulfate by titrating against a standard solution of an oxidizing agent, such as potassium dichromate or potassium permanganate. Ammonium ion in the aqueous solution may be determined by colorimetry, titrimetry, or ion-specific electrode method (see Ammonia). 

Elemental composition Ba 72.52%, C 12.68%, N 14.79%. Barium metal can be analyzed by various instrumental and wet methods (see Barium). Cyanide ion in the aqueous solution of the compound may be determined by using a cyanide ion-specific electrode or by colorimetry using pyridine-barbituric acid reagent (APHA, AWWA, and WEF. 1999. Standard Methods for the Examination of Water and Wastewater, 20th ed., Washington, DC American Public Health Association). 

Elemental compostion Ce 25.56%, H 1.47%, N 20.44%, 0 52.53%. The aqueous solution of the compound may be analyzed for Ce by AA or ICP spectrophotometry. Also, the solution may be measured for NH4 ion by ammonium ion-selective electrode and the NO3 ion by nitrate ion-specific electrode, ion chromatography or cadmium-reduction colorimetry. For all these measurements, the solution may require sufficient dilutions. For quantitation, its solution may be standardized by titration with a reducing agent such as sodium oxalate in the presence of iron and ferroin indicator. 

Elemental composition Pb 73.16%, F 26.84%. A small measured quantity of the compound is hydrolyzed in water and the aqueous solution is appropriately diluted and analyzed for fluoride ion, either by ion-specific electrode or... 

Elemental composition (anhydrous salt) Li 10.07%, N 20.32%, 0 69.62%. A diluted aqueous solution may be analyzed for lithium by AA or ICP method (See Lithium) and nitrate ion by either ion-specific electrode or by ion chromatography. 

Elemental composition Hg 79.40%, C 9.51%, N 11.09%. Aqueous solution is analyzed for mercury metal by AA-cold vapor techniques or by ICP/AES (see Mercury). The cyanide ion may be measured by cyanide ion-specific electrode or by ion chromatography after appropriate dilution. 

Elemental composition Hg 61.80%, N 8.63%, O 29.57%. The compound dissolved in dilute hydrochloric acid and the solution diluted appropriately and analyzed for mercury by cold vapor—AA technique. The aqueous solution is analyzed for nitrate ion by nitrate ion-specific electrode or by ion chromatography. 

Nitrogen dioxide can be identified by color, odor, and physical properties. It is dissolved in warm water and converted to nitric acid. The latter may be measured by acid-base titration or from analysis of nitrate ion by nitrate ion-specific electrode or by ion chromatography. Alternatively, nitrogen dioxide may be passed over heated charcoal to produce nitrogen and carbon dioxide that may be analysed by GC-TCD or GC/MS (See Nitrogen, Analysis). The characteristic masses for N2 and CO2 formed for their identification are 28 and 44, respectively. 

Nitryl chloride may he identified by its mass spectra. The characteristic mass ions are 81, 83, 46, 35, and 37. Alternatively, nitryl chloride maybe identified from its physical and chemical properties (See Reactions). The wet analytical method involves treatment with an excess solution of NaOH and titrating the excess NaOH with a standard solution of H2SO4. Alternatively, nitryl chloride is decomposed in water, and the acids HNO3 and HCl formed are measured by titration or the NO and CH determined by ion specific electrodes or ion chromatography. 

Elemental composition Sr 41.40%, N 13.24%, 0 45.36%. An aqueous solution of the salt may be analyzed for strontium by AA, ICP, or other methods. The nitrate anion may be measured by ion chromatography or by nitrate ion-specific electrode. 

Elemental composition (in anhydrous salt) Th 48.33%, N 11.67%, O 40.00%. The aqueous solution may be analyzed for thorium (See Thorium) and for nitrate ion by ion chromatography, nitrate ion-specific electrode, and colorimetric methods. The water of crystaUization can be determined by DTA, TGA, and other gravimetric methods. 

Elemental composition Zn 55.68%, C 20.46%, N 23.86%. A small and measured amount is treated with dilute sulfuric acid. Hydrogen cyanide generated is swept with a purging gas and collected in sodium hydroxide solution. The solution is analyzed for cyanide by a colorimetric method using pyridine-barbituric acid reagent or by cyanide ion-specific electrode (See Hydrogen Cyanide, Analysis). The acid solution may be analyzed for zinc to measure its content in the compound. 

Sodium and potassium may be quantified by flame photometry, atomic absorption spectroscopy or ion specific electrodes. 

Ca-ion electrode. Ca2 + activity (rather than concentration) can be determined rapidly and accurately using a Ca2 + ion-specific electrode. Care must be exercised to ensure that the potentiometer is properly standardized using solutions that simulate the composition of milk serum. The Ca2 + activity is lower than the Ca2 + concentration - values of about 2 mM have been reported. 

Just before World War II monochlor- and monobromacetic acids were used both in the United States and in Europe, but they are now prohibited. To detect organic bromide or chloride, liquid-liquid extraction is commonly used followed by destruction of the organic matter and use of the Volhard or other classical procedures. Ion-specific electrodes... 

GLC, atomic absorption and mass spectrophotometry, enzymatic, and specific colorimetric procedures seem to be the likely candidates for routine use in the future. Automation will certainly be common. GLC is now used to detect imitation muscat wines (127). Characteristic flavor byproducts of yeasts may be detected and measured. Multiple correlation of the amounts of the more influential major and minor constituents with wine quality is the goal of such research. A simple apparatus for the simultaneous determination of the redox potential (two platinum electrodes), pH, specific conductivity, oxygen, and carbon dioxide (ion-specific electrode) has been devised (128). Molecular oxygen in wines has been determined by several procedures—polarography (129) and GLC being the latest. 

These results suggest that interactions between silicate species and surfactant micelles are weak in the precursor solution. The absence of any organization in the system prior to precipitation seems to indicate that the most important step in the process is the formation of siliceous prepolymers. The interaction of these prepolymers with surfactants could be responsible for micelle growth and subsequent reorganization of the silica/micelle complexes into ordered mesoporous structures. Such a hypothesis might be confirmed by preliminary potentiometric measurements using a bromide ion-specific electrode the amount of free bromide anion increasing at pH around 11 when the polymerization of silica starts. 

Other optional experiments may be completed if time allows. For example, the effectiveness of various redox dyes may be analyzed. In addition to those listed in the text, FMN, ferricyanide, and dichlorophenolindophe-nol may be tested (Neumann and Jagendorf, 1964). It has been shown that NH4C1 and amines stimulate proton uptake. If a potassium ion-specific electrode is available, the light-induced efflux of K+ from spinach chloroplasts may be studied (Dilley, 1972). 

Ion-specific electrodes -perchlorates PERCHLORIC ACID AND PERCHLORATES] (Vol 18)... 

---