Iodine concentration

Thiosulfate titration of iodine is limited to an iodine concentration of 7.5 fig/mL (69). The use of organic solvents such as benzene, toluene, chloroform, and carbon tetrachloride as indicators in the titration of iodine have been proposed (70—72). These procedures increase the sensitivity of the titration so that 6.0 fig/mL of iodine can be detected, although a sensitivity of 2 fig/mL has been claimed (73). 

In view of the chromophoric character of the elemental iodine itself, many colorimetric methods have been proposed for the deterrnination of inorganic iodine (88—92). These methods use the visible portion of the spectmm in reading iodine concentrations. In the visible range the extinction coefficient for iodine is not high enough to be used for minute quantities of iodine in water and other solvents (93). Higher sensitivities have been reported for elemental iodine in potassium iodide solutions in the ultraviolet (93,94). 

Generic Trade Company name Iodine concentration. Osmolahty, LD g, iv Ref. 

The net reaction is the disproportionation of H2O2 to H2O + 5O2 and the starch indicator oscillates between deep blue and colourless as the iodine concentration pulsates. 

Each time a molecule of H collides with an iodine molecule, reaction may occur. The frequency of these encounters, for a particular Ha molecule, is determined by how many I molecules are present. Doubling the number of 1 molecules per unit volume would just double the collisions. Tripling the number of I molecules per unit volume would triple the collisions. Since the iodine partial pressure fixes the iodine concentration, the rate of the reaction is proportional to the iodine partial pressure ... 

In addition, the rate that molecules strike the surface depends upon how many molecules there are per unit volume of solution. As the concentration rises, more and more molecules strike the surface per unit time. The rate of precipitation is proportional to the iodine concentration,... 

This may be illustrated by the following example. Suppose that 50 mL of water containing 0.1 g of iodine are shaken with 25 mL of carbon tetrachloride. The distribution coefficient of iodine between water and carbon tetrachloride at the ordinary laboratory temperature is 1 /85, i.e. at equilibrium the iodine concentration in the aqueous layer is 1 /85th of that in the carbon tetrachloride layer. The weight of iodine remaining in the aqueous layer after one extraction with 25 mL, and also after three extractions with 8.33 mL of the solvent, can be calculated by application of the above formula. In the first case, if x, g of iodine remains in the 50 mL of water, its concentration is x,/50 gmL 1 the concentration in the carbon tetrachloride layer will be (0.1 —x1)/25gmL 1. 

A solution of iodine in aqueous iodide has an intense yellow to brown colour. One drop of 0.05M iodine solution imparts a perceptible pale yellow colour to 100 mL of water, so that in otherwise colourless solutions iodine can serve as its own indicator. The test is made much more sensitive by the use of a solution of starch as indicator. Starch reacts with iodine in the presence of iodide to form an intensely blue-coloured complex, which is visible at very low concentrations of iodine. The sensitivity of the colour reaction is such that a blue colour is visible when the iodine concentration is 2 x 10 " 5 M and the iodide concentration is greater than 4x 10 4M at 20 °C. The colour sensitivity decreases with increasing temperature of the solution thus at 50 °C it is about ten times less sensitive than at 25 °C. The sensitivity decreases upon the addition of solvents, such as ethanol no colour is obtained in solutions containing 50 per cent ethanol or more. It cannot be used in a strongly acid medium because hydrolysis of the starch occurs. 

Only freshly prepared starch solution should be used. Two millilitres of a 1 per cent solution per 100 mL of the solution to be titrated is a satisfactory amount the same volume of starch solution should always be added in a titration. In the titration of iodine, starch must not be added until just before the end point is reached. Apart from the fact that the fading of the iodine colour is a good indication of the approach at the end point, if the starch solution is added when the iodine concentration is high, some iodine may remain adsorbed even at the end point. The indicator blank is negligibly small in iodimetric and iodometric titrations of 0.05M solutions with more dilute solutions, it must be determined in a liquid having the same composition as the solution titrated has at the end point. 

Undiluted RCM with an iodine concentration of 300-320 mg/ml. If the patient notices a positive reaction (pruritus, erythema) at the skin test site at other time points, additional readings may be performed (e.g. after 24 or 96 h). ... 

The amount of free iodine the solution can generate is termed the available iodine. This acts as a reservoir for active iodine releasing it when required and therefore largely avoiding the harmful side-effects of high iodine concentration. Consequently, when used for antisepsis, iodophors should be allowed to remain on the skin for 2 minutes to obtain full advantage of the sustained-release iodine. 

Phenyl iodide chemisorbs dissociatively at a Cu(110) surface at 295 K with structural information being obtained from STM and chemical information from XPS.28 At low exposures (6 L), the surface concentrations of carbon and iodine species, calculated from the intensities of the C(ls) and I(3d) spectra, were in the expected 6 1 ratio and the iodine concentration 5.1 x 1014cm 2. With further exposure, the iodine concentration increased and reached a maximum value of 5.5 x 1014cm-2 after an exposure of 1200L. This was... 

The reaction is believed to be first order in each reactant and second order overall. The following data were reported for their experiments at 20 °C using an iodine concentration of 0.422 x 10 3 kmoles/m3. 

For example, when benzoyl peroxide is allowed to decompose in the presence of an olefin and iodine a high yield of the olefin dibenzoate is formed And very little carbon dioxide. Since Hammond has shown that the rate of the decomposition is independent of the iodine concentration, the iodine must not participate in the rate-determining initial step. It probably reacts with the benzoyloxy radicals to form benzoyl hypoiodite.U8>11 ... 

During the 2007 field experiments, C02 concentrations of the water samples under the reservoir pressure could not be correctly monitored due to the broken of the water sampler. This means that water samples were collected around 800m depth and a part of C02 must be degassed during ascending to the surface from the sampler. Therefore, C02 concentrations of the reservoir fluids are calculated on the basis of the observed pH and charge balance of each samples (Case 1) and the tracer concentration (Case 2). The Case 2 means that C02 in the injected water did not react with rocks. Fig.3 shows the calculated C02 concentration with iodine. Iodine concentration decreases from 1000 to 200pg/L with the elapsed time. From Fig.4, the fraction of the injected C02 water (1 wt.% C02) is almost zero. This means that... 

Complexes with Iodine. One of the simplest "reactions" of poly(vinyl alcohol) is the formation of a blue complex with iodine. This complex formation, which requires the presence of KI, has been studied extensively by many workers (26-31). This complex also forms with partially hydrolyzed poly(vinyl acetates) (26) and is known to be affected by the 1,2-glycol content and the isotacticity of the polymer both of which tend to reduce complex formation (31). The complex also depends on the molecular weight of the poly(vinyl alcohol) and the iodine concentration. 

Since there is direct proportionality between the iodine concentration within the tissue or vessel and X-ray attenuation, pharmacokinetic parameters can be calculated from time-density curves. In CT, 30 HU correspond to approximately 1 mg iodine g tissue [6]. This is a rather high local concentration of radioopaque material, thus underlining the relatively low sensitivity of CT that counterbalances its high specificity. 

The maximum injected volume was 50 mL kg" [25]. LD50 was thus limited by the iodine concentration of the solution in the case of P743 and P840 and the NS-CA iobitridol. Thus, the intravenous acute systemic tolerance by the route intended for use in clinical practice was found to be satisfactory (Table 5). 

Torchilin et al. synthesized an iodine-containing amphiphilic block-copolymer consisting of iodine-substituted poly-L-lysine which is able to form micelles in aqueous solution [37]. The two components of the block-copolymer were methoxy-poly(ethylene glycol) propionic acid (MPEG-PA) with a molecular weight of 12 kDa and poly[ ,M-(2,3,5-triiodobenzoyl)]-L-lysine. The particle size of the micelles was approx. 80 nm, and the iodine concentration was 20 mg mL . Biodistribution studies in rats showed significant and prolonged enhancement of the aorta, the liver and spleen. 

Leander et al. described ready-to-use liposomes that were effective and well tolerated in humans [61]. The iodinated contrast agent was the non-ionic dimer, iodixanol. The particle size of the liposomes was 350 nm with an iodine concentration of 70-80 mg mL encapsulated. They injected doses of 30, 70 or 100 mgl kg intravenously and found maximal enhancement values of 45 HU in the liver and 240 HU in the spleen. The uptake into these organs was not linealy correlated with the injected dose. No serious or unexpected adverse reactions were reported. Dose-dependent changes in leukocyte counts and body temperature were seen. 

The basis for contrast agents derived from nutrional products was Intralipid, which had been prepared from phospholipids obtained from soy bean oil and egg yolk [86]. Intralipid was chemically modified by iodination into Intraiodol, which contained 50 mgl mbThe particles formed in the emulsion were mostly taken up by the hepatocytes and to a lesser extent by the RES [87,88]. Intraiodol was better tolerated than EOE-13 or its precursor, AG 60.99. The addition of cholesterol to Intraiodol resulted in NRI 757 with an iodine concentration of 42 mg mL b Further modifications by replacing the iodinated triglycerides of Intraiodol by ethiodized poppy seed oil and reducing the cholesterol content to... 

The dependence of the mobilities of amylopectin and amylose on iodine concentration in the background electrolyte and applied temperature was studied by Brewster et al. (111). The method was used for the separation and identification of different plant starches, but no binding constants were calculated. 

In the United States and most parts of the world, iodine is obtained com-merciaUy from brine wells. Many subsurface brines have iodine concentrations in the range of 10 to 100 mg/L. Various extraction processes are known including (i) precipitation with silver nitrate, (ii) oxidation with chlorine, and (hi) ion exchange. In the chlorine oxidation process, natural subsurface brine first is acidified with sulfuric acid and then treated with chlorine. Chlorine hberates iodine from the brine solution. Iodine is blown out into a counter-current stream of air. It is dissolved in a solution of hydriodic acid and sulfu-... 

Iodine in water also may be determined by the Leucocrystal violet colorimetric method. An aqueous sample is treated with mercuric chloride followed by Leucocrystal violet reagent [4,4 ,4 —methylidynetris(N,N-dimethylani-hne)] in the pH range 3.5 to 4.0. A violet color is produced. The absorbance or transmittance is measured at 592 nm by a spectrophotometer or filter photometer. Iodine concentration is calculated from a standard calibration curve. 

Singular characteristics of the ruthenium catalysts are the capability of direct activation of different substrates (alcohols, ethers, formic,orthoformic and other carboxylic acid esters) at a low iodine concentration, and a high flexibility toward carbonylation and/or homologation processes for the substrates used. The catalytic activity of the ruthenium catalysts moreover do not strongly decrease, as occurs with Co or Rh systems, by passing from methyl to higher oxygenated alkyl derivatives. 

Dissolve 30 grms. of potassium chlorate in 60 c.c. of warm water contained in a 250 c.c. flask. Add 35 grms of iodine, and then 2 c.c. of cone, nitric acid. A vigorous reaction sets in chlorine gas along with a little vapour of iodine escapes. When the reaction subsides, boil the liquid to drive off the dissolved chlorine, and then add another gram of iodine. Concentrate the soln. by evaporation, and collect the crystals of potassium iodate on a Buchner s funnel. The crude product is purified by dissolving it in about 150 c.c. of hot water, neutralize the soln. with potassium hydroxide, and on cooling crystals of the desired salt are obtained. 

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