Iodide determination

In the second part of the paper 6.10 [143] this writer generalises his new kinetic treatment of living polymerisations [134], By applying it to data from the literature, he shows how this treatment can reveal which one of the components of a binary syncatalytic system (e.g. I2 and organic iodide) determines the concentration of the propagating species and, much more important, how the rate-constant of propagation can be calculated from readily available data. There remains here a rich mine of information to be exploited by others. 

W. A. Wyatt, F. V. Bright and G. M. Hieftje, Characterization and comparison of three fiber-optic sensors for iodide determination based on dynamic fluorescence quenching ofrhodamine 6G, Anal. Chem. 59, 2272-2276 (1987). 

F = Sample volume in milliliters used in the titration for iodide determination. 

D. Doedens, Iodide determination in blood by capillary gas chromatography, J. Anal. Toxicol., 9 109-111 (1985). 

Wu et al. [818] have described a method for the derivatisation of iodide into pentafluorobenzyl iodide using pentafluorobenzyl bromide. The derivative was analysed at ig levels by gas chromatography with electron capture detection. The effects of solvent, water content, base or acid concentration, amount of pentafluorobenzylbromide, reaction time and reaction temperature were examined. Interferences by common anions were minimal. The method was applicable to iodide determination in spring water. 

Add a small amount of an internal standard (decane or undecane, ca. 2-5 mol% compared to the alkyl iodide) to the starting iodide. Determine the initial ratio Ag between the integration of the alkyl iodide and the internal standard by GC analysis. Now start the zinc insertion reaction as described elsewhere. After completion of the reaction, perform a hydrolysis and iodolysis of a reaction sample. 

The first important quantitative paper on steric effects in quaternization of heteroaromatics was by Brown and Cahn (55JA1715). The reaction rate constants for reaction of 2- 3-, and 4-monoalkylpyridines with methyl, ethyl, and isopropyl iodides, determined in nitrobenzene at several temperatures (Scheme 6), are summarized in Table II,... 

The sensitivity of the iodide determination is enhanced six-fold if iodide ions are first oxidized to iodate ions which, in turn, are made to react with added potassium iodide in an acidic medium ... 

Let us consider the determination of iodides as an example. The reaction method of iodide determination was proposed by Hasty [137, 138]. It is based on iodination of ketones in an acidic medium followed by determination of the resulting iodoketone by gas-liquid chromatography using an electron-capture detector. The method was later improved by using butanone-2 instead of acetone, which made it possible to increase the detection sensitivity [139]. A similar method for determining the total content of inorganic iodine in milk was proposed by Bakker [140]. The detection limit does not exceed lOmg/1. It is a sufficiently accurate method with a relative standard deviation of 1.9%. 

The polarogram was obtained on isopropamtde (SK+F standard SJB- + i-06-226A ) in 0-1 N potassium nitrate with a standard calomel/dropping mercury electrode system at a concentration of 5 x 10 molar (9) The E 1/2 was -0.25 V- The E 1/2 for iodide determined under similar conditions was -0.225 V. 

Contribution To The Development Of Indirect Atomic Absorption Methods Application Of The Ion Pair l,10-Phenanthroline-Mercuiy(II)-Iodide To Iodide Determination In Water And Infant Formulae Samples. Mikrochimica Acta, Vol.131, No.3-4, pp 145-151, ISSN 00263672... 

Due to its high capacity, sample preparation other than membrane filtration is not required. Furthermore, by detecting iodide via its UV absorption, matrix anions such as chloride, sulfete, and bicarbonate are not detected and thus do not interfere with iodide determination. Figure 10.53 shows the separation of iodide spiked into natural seawater collected in Half Moon Bay, CA, USA. As shown, iodide is easily determined by UV detection with a recovery of 96%. 

Iodide ions can be determined quite well with argentimetric titrations. The Volhard method, electrometric endpoint indications, and adsorption indicators work well. The Mohr endpoint indication, however, does not give good results because of the adsorption of the chromate on the silver iodide precipitate. The presence of chloride and bromide ions disturbs the argentimeric iodide determination. 

The silver nitrate solutions are now combined, diluted with several volumes of water, acidified with nitric acid, boiled gently for several minutes, and the silver iodide determined gravimetrically. 

N.Konno, K.Yuki, H. Taguchi, K. Miura, S. Taguchi, K. Ha giwara and S. Murakami. Screening for thyroid diseases in an iodine sufficient area with sensitive thyrotropin assays, and serum thyroid autoantibodies, and urinary iodide determinations. Clin. Endocrinol, (submitted)... 

Like the corresponding nonionic compounds, alkyl ether sulfates may be degraded by hydriodic acid cleavage, with the resulting alkyl iodides determined by reversed-phase HPLC (46). 

The equilibrium constant of this second reaction is so large 10" ) that only a vanishingly small CN" ion concentration remains near the electrode surface. The Ag(CN)2 formed diffuses into solution along with the iodide ion. Now, however, this free iodide determines the electrode potential, since once the electrode phase has started to dissolve the remaining phase responds to the Ag ions in solution, whose activity is controlled by the iodide concentration. Two cyanide ions are required to liberate one iodide ion, so the Nemst equation for this reaction is ... 

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