Determination of iodine value

The iodine value of a fatty material is the amount of iodine, expressed as a percentage, required to saturate all the double bonds in the sample. It is not very reliable as a measure of the unsaturation in absolute terms, but is useful as an empirical parameter in setting specifications. 

The method uses Wij s reagent, which is a 0.2mol/l solution of iodine monochloride in glacial acetic acid, and which is most conveniently purchased ready-made. The reaction with an unsaturated compound is addition across the double bond. This is traditionally represented as the addition of a molecule of iodine monochloride, but as it is necessary to 

An iodine flask is a conical stoppered flask having a deep well round the neck, into which a solution may be poured when the stopper is in place. 

Mix the sample and accurately weigh about 20/1V g, where IV is the expected iodine value, into an iodine flask or a 250 ml conical flask. It may be more convenient to weigh the sample into a small glass or plastic capsule and place this in the flask. 

Add 10 ml chloroform (caution toxic vapour) and swirl to dissolve the sample. 

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Infrared spectra of fats and oils are similar regardless of their composition. The principal absorption seen is the carbonyl stretching peak which is virtually identical for all triglyceride oils. The most common appHcation of infrared spectroscopy is the determination of trans fatty acids occurring in a partially hydrogenated fat (58,59). Absorption at 965 - 975 cm is unique to the trans functionaHty. Near infrared spectroscopy has been utilized for simultaneous quantitation of fat, protein, and moisture in grain samples (60). The technique has also been reported to be useful for instmmental determination of iodine value (61). 

The determination of iodine value (IV), AOCS Tg 1-64, is sometimes used to determine the extent of unsaturation. Because the tertiary aUyflc hydrogen ia the compounds is capable of substitution by halogen atoms, this only approximates a value for the degree of unsaturation. 

Automatic Pipettes (Transfer Pipettes) Automatic pipettes are always preferred to ordinary transfer pipettes because of their ability to handle corrosive and toxic liquids in routine analytical laboratories, e.g., determination of Iodine Value in edible oils by iodine-monochloride (IC1) solution. 

Table D1.4.1 Sample Weights to be Used for Determination of Iodine Values Expected Iodine Value...

Annex XVI Determination of iodine value A method for the determination of iodine value of olive oil. The iodine value is expressed as g of iodine per 100 g of oil To obtain information on degree of unsaturation of an oil... 

Cox, R., Lebrasseur, J., Michiels, E., Buijs, H., Li, H., van de Voort, F.R., Ismail, A.A., and Sedman, J. 2000. Determination of iodine value with a Fourier transform-near infra red based global calibration using disposable vials an international collaborative study, J. Am. Oil Chem. Soc., 77, 1229. 

Ng, S. and Gee P.T. 2001. Determination of iodine value of pahn and palm kernel oil by carbon-13 nuclear magnetic resonance spectroscopy. Fur. J. Lipid Sci. TechnoL, 103,... 

Determination of iodine value /,) According to the (Wijs) lUPAC (1964) method (lUPAC Standard Methods for the Analysis of Oils, Fats and Soaps, 5th edition, 1966 II.D.7.1., II. D.7.2 and II.D.7.3 The wijs Method). Results are expressed as percentage of mass per mass absorbed iodine. 

Vegetable oil is a relatively simple mixture of fatty acids and lends itself to MIR/NIR analyses. The unsaturation is easily seen in all the vibrational spectroscopic techniques discussed thus far. Because the iodine number may be easily seen, the hydrogenation of vegetable oil to margarine should also be an easy analysis to perform in real time. Multiple simultaneous determinations of iodine value, protein, moisture, and color are relatively routine in nature. Simple PLS or MLR algorithms make this an efficient method for obtaining these values in an in-process measurement. 

KAS II activity was assayed as described by MacKintosh et. al [1]. One unit KAS II activity was defined as 1 nmol of [ " C]-malonyl CoA formed per minute derived from the reverse reaction. Determination of iodine value of oil palm mesocarp was carried out according to PORIM Test Methods [2]. 

Each oil has its own characteristic iodine value (varying between narrow limits), and so the determination of iodine value can be utilised to detect and even to determine (though approximately) the extent of contamination in any specific oil. 

The determination of peroxide value (PV) by an iodometric titration is described in Basic Protocol 2. Iodine is liberated by hydroperoxides in the oil in the presence of excess iodide in a stoichiometric ratio. The amount of iodine present is determined by titration with a standard sodium thiosulfate solution using a starch indicator, thereby reflecting how much peroxide is present in the oil or lipid extract. 

Iodine, colorimetric determination of amylase using, 689-692 Iodine value, lipid composition canola oil, 474 (table) oil quality indices, 467-469, 475-477 lodometric titration, determination of peroxide value, 518-519 Ionization techniques, in mass... 

Ivanov (1929) found a close inverse relationship between the value of lipid unsaturation of plants (determined by iodine value) and the latitude of their habitat. It was found that, with lower environmental temperatures, the iodine numbers of the lipids were greater (i.e. there was more unsaturation). The effect of increasing unsaturation is to lower the temperature at which the lipids change from liquids to a liquid-crystalline state, and so to lower the temperature at which the cells remain flexible. 

Oleic Acid Isolate the fatty acids as directed under Laurie Acid in the monograph for Polysorbate 20, and determine the weight of the acid. With the product so obtained, determine the acid value (between 193 and 206) as directed in Method I under Acid Value, Appendix VII. Similarly determine the iodine value (between 80 and 92) as directed under Iodine Value, Appendix VII. 

In one of the most reliable determinations of the value of the faraday which has been made, Vina and Bates found that 4.82844 g of iodine was liberated at an anode in potassium iodide solution by 3671.82 coulombs of electricity. Evaluate the faraday from this information, using 126.92 for the atomic weight of iodine. 

P rowicz J., Walfga E. PN-83/C-97555.04. Activated carbon. Method of test. Determination of adsorption value of iodine. 

An X-ray fluorescence method has been developed for in vivo determination of iodine in thyroid (Aubert et al., 1981 Jonckheer and Deconinck, 1982). This method is based on the irradiation of iodine in the thyroid by o(-rays provided by a -source, such as Am. The excited iodine atoms emit a characteristic X-ray fluorescence radiation, which is proportional to the amount of iodine present in the gland. The reported detection fimit reaches 0.01 mg/ml thyroid, this value is much lower than the iodine concentration in thyroid. The reported radiation dose equivalent is only 60mSv per measurement. This method has been successfully used for the clinical determination of in thyroid (Milakovic et al., 2006 Reiners et al., 1996, 2006 Briancon et al., 1992). An indirect method was also reported to determine of thyroid iodine in vivo (Imanishi et al., 1991), which is based on the relationship of CT attenuation values with iodine concentration in the thyroid. It was reported that the CT value correlated finearly with iodine concentration in thyroid nodules when iodine concentration was higher than 0.02 mg/g. 

Salt quality monitoring should be reinforced to ensure that the level of salt fortification with iodine is not too high, but is adequate to ensure optimal iodine nutrition. Salt iodine concentration, which was used in the childrens households, was monitored. The determination of iodine in table salt showed that the commercial products contain iodine in concentrations very close to the upper limit 57.5 12.7mg/kg (maximum value 79.3mg/kg, minimum value 43.0mg/kg, = 6). Only one of the analyzed samples was from a local producer and the others were imported from European and non-European countries. Therefore, the import of table salt should also be controlled. 

Because the IV is a measure of the relative unsaturation of a compound or sample, other analytical techniques (e.g., gas chromatography of FA composition, AOCS Cd lc-85) can be used to estimate the value. Interest in recent years has focused on spectroscopic techniques for the rapid determination of TV. Fourier transform (FT)-near-infrared, near-infrared, FT-Raman, and H and nuclear magnetic resonance (NMR) spectroscopic techniques have all been investigated (Ng and Gee, 2001). The most promising results have been obtained with FT-near-infrared spectroscopy, which only takes a few minutes to determine the iodine value (Cox et al., 2000). 

Simon et al. (Simon et al., 2002) presented an example of the value of the determination of iodine compoxmds in fish. The authors analyzed whole-body homogenates of zebrafish (Danio rerio) and tadpoles of the African clawed frog (Xenopnis laevis). They detected five previously unknown iodinated compounds and measured the concentrations of I-, MIT, DIT, T4, T3 and rT3 in these sp>ecies. 

The qu.ilitative and quantitative determinations of the polyunsaturated acids have posed exceedingly refractory problems, and they have only recently been partially resolved. The former methods were tedious and of such uncertain interpretation that they were of little value. Frequently, they were resolved by the very unsatisfactory expedient of measuring changes of iodine value. It is obvious that only the simplest generalizations can be arrived at by such procedures. 

Peroxide value determination, "CSN 580130, part 4 - 1986 747 TAKAGI, ., MITSUNO,Y.,MASUMURA,M. Determination of peroxide value by the colorimetric iodine method with protection of iodide as cadmium complex, "Lipids", (2),147-152 (1978)... 

In this section, we consider the determinations based on the addition of bromine on double bonds. Most of the time, these addition reactions take place in nonaqueous media. We limit ourselves to recall the notions of iodine value and fat indices. Some drugs are determined by the addition of bromine on a double bond that their structures contain. We ll first consider cyclobarbital and hexobarbital, which are derived from barbituric acid ... 

Determine the iodine value allowing a value of 90 for unsaturated acids Figures for natural oils (except rape) were about 2 to 3 per cent but partially hydrogenated oils gave values of 20 to 50 per cent. 

The methods for determining the iodine value of lipids are Hanus method and Wijs method. The lipid to be analyzed is weighed and dissolved in a suitable organic solvent, to which a known excess of iodine monobromide (or the monochloride) is added. Some of the IBr reacts with the double bonds in the imsaturated lipids, whereas the rest remains unreacted ... 

Healthy euthyroid and nongoitrous subjects have been investigated for iodine intake directly and indirectly, by various methodologies including the determination of stable iodine concentration on 24 hr excretion collections (either directly measured on 24 hr urine collections or calculated by the use of the iodine/creatinine or l/Cr ratio), the determination of iodine concentration in the urines, iodine kinetic studies (particularly of the inorganic iodine compartment) and iodine balance studies as well. Most of the values are given as mean standard deviation the standard error of the mean (sem) is specified when used. 

The evaluation of the iodine nutritional status was based on the determination of iodine concentrations in a large series of casual urine samples. 1 In 196 infants from the Brussels area, the median urinary iodine concentration was 4.8 iig/100 ml, 53% of the values being below 5 flg/dl. The urinary excretion of iodine was estimated as 51 lg/day.This in turn, enhances the susceptibility of the newborn, and particularly the premature to transient neonatal hypothyroidism.l ... 

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