Iodide analysis

Iodargyrite, natural occurrence of, 22 668 Iodates, 14 374-375 Iodate solutions, 14 362 Iodic acid, 14 375 Iodide analysis, of water, 26 41 Iodide ion, 14 367-368 25 488 Iodide-refining method, 26 149 for vanadium, 25 520 Iodides, 14 374 thorium, 24 763 tungsten, 25 379-380 uranium, 25 439... 

Treatment of a cooled (ice-salt bath) solution of the dibenzothiepinone 1 in NMP with sodium hydride gave a deep red solution which was largely decolourised on addition of methyl iodide. Analysis of the reaction mixture showed the presence of unreacted starting material and three new products the latter were identified as the 6-methyl derivative and the ethers 2 and 3. 

Often, greater accuracy may be obtained, as in Volhard type titration, by performing a back titration of the excess silver ions. In such a case, a measured amount of standard silver nitrate solution is added in excess to a measured amount of sample. The excess Ag+ that remains after it reacts with the analyte is then measured by back titration with standard potassium thiocyanate (KSCN). If the silver salt of the analyte ion is more soluble than silver thiocyanate (AgSCN), the former should be filtered off from the solution. Otherwise, a low value error can occur due to overconsumption of thiocyanate ion. Thus, for the determination of ions (such as cyanide, carbonate, chromate, chloride, oxalate, phosphate, and sulfide, the silver salts of which are all more soluble than AgSCN), remove the silver salts before the back titration of excess Ag.+ On the other hand, such removal of silver salt is not necesary in the Volhard titration for ions such as bromide, iodide, cyanate, thiocyanate, and arsenate, because the silver salts of these ions are less soluble than AgSCN, and will not cause ary error. In the determination of chloride by Volhard titration, the solution should be made strongly acidic to prevent interference from carbonate, oxalate, and arsenate, while for bromide and iodide analysis titration is carried out in neutral media. 

Methods utilizing newer techniques including ITMS, CE, and GC/MS/MS have recently been developed. ITMS analysis by Curcuruto et al. ° and Traldi et al. readily demonstrated the presence of morphine in hair. Free zone CE with amperometric detection was sensitive and highly selective. A novel procedure by Polettini et al. describes the treatment of methanol-washed samples with a silylating solution, followed by injection into GC. The silylating reagent was prepared by mixing MSTFA with dithioerythritol and ammonium iodide. Analysis of heroin, 6-AM, acetylcodeine. 

UI was analyzed for NHANES III using the SandeU-Kolthoff colorimetric method (SandeU and Kolthoff, 1937), whereas isotope dilution inductively coupled plasma mass spectrometry (ICP-MS) was used for urine iodide analysis of the iodine measured in NHANES 2001— 2002 (Allain et al., 1990). Therefore, data from NHANES III should be compared cautiously with that obtained in NHANES 2001-2002 (Soldin, 2002 Caldwell et ai, 2003 Haldimann et ai, 1998). 

The effect of sample preservation on determination of F in healthy and pathological human thyroids has also been studied (Blazewicz et al., 2011). It was pointed out that the way of tissue preservation (either in formalin or by freezing) had no significant effect on the iodine determination result (a = 0.1) by ion chromatography combined with the pulsed amparometic detection method (IC-PAD). Sample decomposition is a critical step in iodides analysis as well. All reported methods have a digestion or ashing step prior to the final determination of... 

Bruggink, C., van Rossum, W. J. M., Spijkerman, E. van Beelen, E. S. E. (2007). Iodide analysis by anion-exchange chromatography and pulsed amperometric detection in surface water and adsorbable organic iodide. Journal of Chromatography A, Vol. 1144, No.2, pp 170-174, ISSN 0021-9673... 

The classical Zeisel method for the determination of ether (59) consists of digesting the substrate with hydrogen iodide. Analysis shows that the reaction proceeds in a favorable manner as designated by Saville. Sulfides do not interfere with the determination because the hard-soft combination is incorrect in such cases. 

Figure 10.420 Iodide analysis in a birdseed sample after oxidative combustion. Separator column lonPac ASM eluent 30mmol/L NaCI flow rate 1.5 mlVmin detection UV (236nm) sample birdseed with 266mg/kg iodide (1) (see [716]).

This value still assures a sharp end point jump in the titration curve. This same example for a chloride rather than iodide analysis would be far less favorable, since the solubility product of AgCl is only 10" . With a starting chloride ion concentration of 10 M, Pp is only 10". This value would allow a final accuracy of 0.1% only under the most highly favorable conditions (extremely careful titer determination, using a standard having the same matrix as the sample solution and standardized analytical procedures). Here any diluting of the sample would smear out the end point. 

Consequently, when D /Dj exceeds the critical value, close to the bifurcation one expects to see the appearance of chemical patterns with characteristic lengtli i= In / k. Beyond the bifurcation point a band of wave numbers is unstable and the nature of the pattern selected (spots, stripes, etc.) depends on the nonlinearity and requires a more detailed analysis. Chemical Turing patterns were observed in the chlorite-iodide-malonic acid (CIMA) system in a gel reactor [M, 59 and 60]. Figure C3.6.12(a) shows an experimental CIMA Turing spot pattern [59]. 

The ability of the solid chlorates(V) to provide oxygen led to their use in matches and fireworks. Bromates(V) and iodates(V) are used in quantitative volumetric analysis. Potassium hydrogen diiodate(V), KHflOjlj, is used to standardise solutions of sodium thiosulphate(Vf) since in the presence of excess potassium iodide and acid, the reaction... 

Absolute diethyl ether. The chief impurities in commercial ether (sp. gr. 0- 720) are water, ethyl alcohol, and, in samples which have been exposed to the air and light for some time, ethyl peroxide. The presence of peroxides may be detected either by the liberation of iodine (brown colouration or blue colouration with starch solution) when a small sample is shaken with an equal volume of 2 per cent, potassium iodide solution and a few drops of dilute hydrochloric acid, or by carrying out the perchromio acid test of inorganic analysis with potassium dichromate solution acidified with dilute sulphuric acid. The peroxides may be removed by shaking with a concentrated solution of a ferrous salt, say, 6-10 g. of ferrous salt (s 10-20 ml. of the prepared concentrated solution) to 1 litre of ether. The concentrated solution of ferrous salt is prepared either from 60 g. of crystallised ferrous sulphate, 6 ml. of concentrated sulphuric acid and 110 ml. of water or from 100 g. of crystallised ferrous chloride, 42 ml. of concentrated hydiochloric acid and 85 ml. of water. Peroxides may also be removed by shaking with an aqueous solution of sodium sulphite (for the removal with stannous chloride, see Section VI,12). 

CAUTION. Ethers that have been stored for long periods, particularly in partly-filled bottles, frequently contain small quantities of highly explosive peroxides. The presence of peroxides may be detected either by the per-chromic acid test of qualitative inorganic analysis (addition of an acidified solution of potassium dichromate) or by the liberation of iodine from acidified potassium iodide solution (compare Section 11,47,7). The peroxides are nonvolatile and may accumulate in the flask during the distillation of the ether the residue is explosive and may detonate, when distilled, with sufficient violence to shatter the apparatus and cause serious personal injury. If peroxides are found, they must first be removed by treatment with acidified ferrous sulphate solution (Section 11,47,7) or with sodium sulphite solution or with stannous chloride solution (Section VI, 12). The common extraction solvents diethyl ether and di-tso-propyl ether are particularly prone to the formation of peroxides. 

The reaction product is cooled to room temperature, is washed with 10 ml of H2O to the purpose of removing lithium iodide and is then dehydrated over NaiS04. 3.57 g is obtained of dimethoxy-phenylacetone (III), as determined by gas-chromatographic analysis with an inner standard of 4,4 -dimethoxybeniophenone. The yield of ketone (III) relative to the olefin ( ) used as the starting material is of 87.1%. 

This experiment describes the quantitative analysis of the asthma medication Quadrinal for the active ingredients theophylline, salicylic acid, phenobarbital, ephedrine HGl, and potassium iodide. Separations are carried out using a Gi8 column with a mobile phase of 19% v/v acetonitrile, 80% v/v water, and 1% acetic acid. A small amount of triethylamine (0.03% v/v) is included to ensure the elution of ephedrine HGl. A UV detector set to 254 nm is used to record the chromatogram. 

An alternative method for the analysis of permanganate is the use of conventional iodometric methods (177) where excess potassium iodide is added to a solution of permanganate under acidic conditions. The Hberated iodide is then titrated with standard thiosulfate solution using starch as an indicator. 

The iodide method can also be appHed to the analysis of other manganese species, but mixtures of permanganate, manganate, and MnO interfere with one another in the iodometric method. 

The hberated iodine is measured spectrometricaHy or titrated with Standard sodium thiosulfate solution (I2 +28203 — 2 1 VS Og following acidification with sulfuric acid buffers are sometimes employed. The method requires measurement of the total gas volume used in the procedure. The presence of other oxidants, such as H2O2 and NO, can interfere with the analysis. The analysis is also technique-sensitive, since it can be affected by a number of variables, including temperature, time, pH, iodide concentration, sampling techniques, etc (140). A detailed procedure is given in Reference 141. 

There are many colorimetric methods used for trace analysis of peroxides using reagents such as ferrous ion, leuco base of methylene blue, yy -diphenylcarbohydrazide, titanium(IV), iodide ion, and Ai,A7-dimethyl- -phenylenediamine. The latter two are the most commonly used reagents... 

Analysis. The abiUty of silver ion to form sparingly soluble precipitates with many anions has been appHed to their quantitative deterrnination. Bromide, chloride, iodide, thiocyanate, and borate are determined by the titration of solutions containing these anions using standardized silver nitrate solutions in the presence of a suitable indicator. These titrations use fluorescein, tartrazine, rhodamine 6-G, and phenosafranine as indicators (50). 

An ion-selective electrode is available for chloride analysis chloride can be measured potentiometrically at 10 -1 M. Iodide and sulfide are the principal interferences. 

Peracid Analysis. Peracid concentrations can be measured in a product or in the bath by use of a standard iodide / thiosulfate titration (60). With preformed peracids or peracids formed via perhydrolysis care must be exercised to minimize the interference of hydrogen peroxide, present intentionally as a component of the perhydrolysis reaction or as a result of the hydrolysis of the peracid (87,88) as shown in equation 18. 

The iodometric analysis method for CIO2 and its coproducts is based on the pH-dependant oxidation of potassium iodide to selectively distinguish the various oxychlorine species from each other (42,89). The reactions of the oxidizer species with iodide at various pH buffered conditions ate... 

Chlorate Analysis. Chlorate ion concentration is determined by reaction with a reducing agent. Ferrous sulfate is preferred for quaHty control (111), but other reagents, such as arsenious acid, stannous chloride, and potassium iodide, have also been used (112). When ferrous sulfate is used, a measured excess of the reagent is added to a strong hydrochloric acid solution of the chlorate for reduction, after which the excess ferrous sulfate is titrated with an oxidant, usually potassium permanganate or potassium dichromate. 

Pyridazinium iodide, 4,5-diamino-1-methyl-3-(methylthio)-analysis, 3, 2... 

The molecular absoi ption spectra, registered at a lower temperature (e.g. 700 °C for iodide or chloride of potassium or sodium), enable one to find the absorbance ratio for any pair of wavelengths in the measurement range. These ratios can be used as a correction factor for analytical signal in atomic absoi ption analysis (at atomization temperatures above 2000 °C). The proposed method was tested by determination of beforehand known silicon and iron content in potassium chloride and sodium iodide respectively. The results ai e subject to random error only. 

One of the most required methods of determination of iodide-ions in praetiee of ehemieal analysis is photometrie determination of produets of iodination of organie eompounds. The oxidation of iodide to iodine ean be earned out suffieiently seleetively. But in ease of presenee of great abundanee of bromide-ions the seleetive oxidation of iodide-ions is problematie. The variants of determination of iodide-ions with different organie reagents are known, but the absenee of bromide-ions in a system is supposed in most of them. In natural objeets these halides are present simultaneously. 

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