Determination of iodine

Hanus solution (for determination of iodine number) dissolve 13.2 g of iodine in a liter of glacial acetic acid that will not reduce chromic acid add sufficient bromine to double the halogen content determined by titration (3 mL is about the right amount). The iodine may be dissolved with the aid of heat, but the solution must be cold when the bromine is added. 

Kalbus, G. E. Lieu, V. T. Dietary fat and Health An Experiment on the Determination of Iodine Number of fats and Oils by Goulometric Titration, /. Chem. Educ 1991, 68, 64—65. 

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. 

Van Vleit et al. [9] have described a semiautomatic spectrophotometric method using a Technicon Autoanalyser for the determination of iodine in soil extracts. The method has a coefficient of variation of 2.1% at the 8.6mg L 1 iodine level to 6.1% at the 1.4mg L-1 iodine level. 

The most important concept when working stoichiometry problems such as this one is moles. We must have moles to proceed. The mole determination of iodine will involve the molar mass of iodine (2 x 126.9 g/mol), while the mole determination of fluorine will involve Avogadro s number (since we have number of fluorine molecules). We can find the moles of each as follows ... 

For the determination of iodine weigh out 20-30 mg. of substance in a small platinum boat and carry out the combustion in the manner described above for the other halogens. Adjust the rate of flow of the oxygen to 4-5 c.c. per minute. 

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. 

Jenkins et al. developed a capillary electrophoresis system for the measurement of iohexol as a marker of the glomerular filtration rate (GFR) with a run time of 5.25 min and a coefficient of variation (CV) of 4.3% at 80 mg L" [121]. The GFR, calculated from the plasma clearance, had a reproducibility of 5.47 %. A similar approach (liquid chromatography-mass spectrometry with positive electrospray ionization after enrichment by solid phase extraction) was applied by Putschew et al. for the determination of iodinated contrast agents in treatment plant effluents and surface waters [118]. 

Iodine and iodine derivatives are ubiquitous in nature and a report describing the determination of iodine in environmental and biological samples has been published [197]. Electrochemical techniques are important, in particular, for inorganic iodine species in aqueous media. The direct detection of iodine by differential pulse and stripping voltammetry has been reported... 

In analogy to sample introduction by hydride generation, mercury trace analysis is possible by reducing Hg compounds to the metal using the cold vapour technique or the determination of iodine at the ultratrace level (after oxidation with 70 % perchloric acid of iodide to iodine) via the gas phase. 

Allegrini, M., Pennington, J. A. T. and Tanner, J. T. 1983. Total diet study Determination of iodine intake by neutron activation analysis. J. Am. Diet. Assoc. 83, 18-24. 

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

Jungreis, E., and I. Gedalia Ultramicro Determination of Iodine in Drinking Water on the Basis of Feigl s Catalytic Reaction. Mikrochim. Acta 1960, 145. 

Van Vliet et al. [15] have described a semi-automated procedure for the determination of iodine in soils. The soil sample is digested with 2 N sodium hydroxide, and then the soil is centrifuged off. The resulting solution is digested with perchloric and nitric acid (2 1 v/v) at 265 °C until clear. Iodine is determined in this solution by a method based on the oxidation of arsenic III by cerium IV 3 - 5 ppm mg/kg added to soil was recovered at the 98% level. 

In comparison, the results of periodate oxidation and the determination of iodine numbers, using sodium hyaluronate, by Jeanloz121 would indicate that the polysaccharide was linear, and had a molecular weight of 18-24,000 (50 units). A further decrease in size of the molecule which... 

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... 

P. A. Fecher, I. Goldmann, A. Nagengast, Determination of iodine in food samples by inductively coupled plasma mass spectrometry after alkaline extraction, J. Anal. Atom. Spectrom., 13 (1998), 977D982. 

P. Fecher, C. Walther, J. Sondermann, Determination of iodine in dietary foods by ICP-MS, Dtsch. Lebensm.-Rundsch., 95 (1999), 133D142. 

D. Andrey, A routine quality control method for the determination of iodine in human and pet food by ICP-MS, Atom. Spectrosc., 22 (2001), 299D305. 

Iodine was determined by GC by Hasty [652]. He carried out the conversion into iodoacetone by reaction with an aqueous solution of acetone (0.5 M) and sulphuric acid (0.5 M) for 30 min. The reaction mixture was then extracted with n-hexane and aliquots were analysed on a column packed with 5% of SE-30 on Varaport. By using an ECD, iodine concentrations down to 1 jug/ml in an aqueous sample could be determined. The sensitivity could be increased by using other ketones, e.g., 2-butanone or 2-pentanone [653]. The products from the reaction with these ketones provide higher ECD response and are more extractable with n-hexane. The utilization of these properties makes it possible to extend the determination of iodine down to concentrations of nanograms per millilitre. 

Grys [654] studied this method in more detail and applied it to the determination of iodine, present as a free element, iodide and firmly bound iodine in milk. A 0.4-ml volume of fresh milk was placed in a 35-ml Kjehldahl swan-necked flask, mixed with 1.0 ml of 2 M potassium carbonate solution, dried at 105°C overnight and then ashed at 600—... 

Portions of this test are adapted from ASTM D 4607-94(1999)— Standard Test Method for Determination of Iodine Number of Activated Carbon. The original ASTM method is available in its entirety from ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428 phone 610-832-9585 fax 610-832-9555 email service astm.org website . 

The moderate reducing character of S203 provides a basis for analytical determination of iodine ... 

Tetrathionates are obtained by treatment of thiosulfates with iodine as in the reaction used in the volumetric determination of iodine mentioned earlier. 

Hu, M., Chen, H., Jiang, Y., Zhu, H. Headspace single-drop microextraction coupled with gas chromatography electron capture detection of butanone derivative for determination of iodine in milk powder and urine. Chem. Pap. 67(10), 1255-1261 (2013)... 

Free radicals react most efficiently with other free radicals, and the chemicals that have relatively stable free radicals, such as 2,2-diphenyl-1-pricylhydrazyl (DPPH), could be used, in principle, to quantitatively estimate the amount of free radicals (DPPH method). The peroxide formed on the surface that derived from free radical could be quantitatively analyzed by the determination of iodine liberated from KI solution, which could be used to calculate the amount of the original free radical from that peroxide was derived (iodine method). 

Cox, R.J., Pickford, C.J. and Thompson, M, Determination of Iodine-129 in vegetable samples by inductively coupled plasma mass spectrometry. J. Anal. Atmos. Spectrom., 7 (1992) 635. 

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