Iodine determination milk

S. Sturup, A. Buchert, Direct determination of copper and iodine in milk and milk powder in alkaline solution by Bow injection inductively coupled plasma mass spectrometry, Fresenius J. Anal. Chem., 354 (1996), 323 D 326. 

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—... 

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)... 

Grys, S. The gas-liquid chromatographic determination of inorganic iodine, iodide and tightly bound iodine in milk. J. Chromatogr. 100, 43 (1974)... 

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%. 

A fluorescence-based method was successfully tested for iodine determination in iodine-supplemented food, such as table salt and milk powder. It is based on the fluorescent quenching capability of iodine/triodide using a highly fluorescent compound consisting of a synthetic metal ion receptor coupled with a signaling element. The detection limit for triodide down to a concentration of 10 mol was reported (Zhao et al., 2003). 

The analysis of the food questionnaire did not reveal a statistically significant influence of a single nutritional determinant (milk, meat, fish and cereal products) on the UI. According to our experience, the discriminatory power of a questionnaire is low. For example, 89% of all 805 subjects reported the use of iodinated salt at home (>3 times per week) and consumption of fish (>1 times per week) was reported by 98% of the participants. This is very unlikely, based on previous investigations in Germany (Merges etaL, 1996). 

A semi-automated method for determination of the total iodine in milk was described by Aumont (Aumont, 1982). The method involved destruction of organic matter by alkaline incineration and automated spectrophometric determination of iodide based on the Sandell and Kolthoff s reaction. The recoveries of the added iodide before calcination were between 90.05 +/- 7.36% and 97.14 +/- 4.56% (mean +/- S.D.). The coefficient of variation ranged from 2.15 to 7.21% depending on the iodine content in the milk. The limit of detection was estimated to be aroxmd 2 pg/kg. 

A flow injection method based on the catalytic action of iodide on the colour-fading reaction of the FeSCN2+ complex was proposed and applied in order to determine iodine in milk. At pH 5.0, temperature 32°C and measurements at 460 nm, the decrease in absorbancy of Fe -SCN (0.10 and 0.0020 mol /I) in the presence of N02" (0.3 mol/ 1) is proportional to the concentration of iodide, with a linear response up to 100.0 pg/1. The detection limit was determined as 0.99 pg/1 and the system handles 48 samples per hour. Organic matter was destroyed by means of a dry procedure carried out under alkaline conditions. Alternatively, the use of a Schoninger combustion after the milk dehydration was evaluated. The residue was taken up in 0.12 mol/1 KOH solubilization. For typical samples, recoveries varied from 94.5 to 105%, based on the amounts of both organic matter destroyed. The accuracy of the method was established by using a certified reference material (IAEA A-11, milk powder) and a manual method. The proposed flow injection method is now applied as an indicator of milk quality on the Brazilian market (de Araujo Nogueira et al., 1998). 

Aumont, G. (1982). A Semi-Automated Method For The Determination Of Total Iodine In Milk. Ann Rech Vet. Vol.l3, No.2, pp 205-210, ISSN 0003-4193... 

De Araujo Nogueira, A. R., Mockiuti, F., De Souza, G. B. Piimavesi, O. (1998). Flow Injection Spectrophotometric Catalytic Determination of Iodine in Milk. Anal. ScL, Vol.l4, pp 559-564, ISSN 1348-2246... 

Fecher P. A., Goldman, 1. A. Nagengast. (1998). Determination Of Iodine In Food Samples By Inductively Coupled Plasma Mass Spectrometry After Alkaline Extraction. Journal of Analytical Atomic Spectometry, Vol.l3, pp 977-982, ISSN 1364-5544 Fernandez-Sanchez, L. Szpunar, J. (1999). Spedation Analysis For Iodine In Milk By Size -Exclusion Chromatography With Inductively Coupled Plasma Mass Spectrometric Detection (SEC-ICP MS). J.Anal. At. Spectrom., Vol.l4, pp 1697-1702, ISSN 1364-5544 Fernandez-Sanchez, L., Bermejo-Barreraa, P., Fraga-Bermudez, Szpunar, J. Lobinski R. 

The radioiodine content of milk can be determined on the basis of iodine extraction from milk with tetrachloromethane (carbon tetrachloride). In this way, only inorganic iodine in milk is determined, and organically bound iodine is obtained after alkali metal fusion and extraction. The activity is measured after the precipitation of silver iodide. 

Iodine determinations (Zak chloric acid procedure) were performed on 52 milk samples from the mothers of randomly selected prems in a Neonatology unit in Madrid, and on 151 samples of formula for prems and 59 samples of formula for normal newborns, used in the same unit over a one-year period. They corresponded to 25 different preparations from 8 different manufacturers. The amount of formula ingested was recorded during a 24 h period of urine collection at different postnatal ages, in 107 prems. 

Vanhoe, H.,Van Allemeersch, F.,Versieck,J., and Dams, R. (1993). Effect solvent type on the determination of total iodine in milk powder and human serum by inductively coupled plasma mass spectrometry. Analyst (London) 118(8), 1015. 

Various methods have been employed to measure the extent of autoxi-dation in lipids and lipid-containing food products. For obvious reasons, such methods should be capable of detecting the autoxidation process before the onset of off-flavor. Milk and its products, which develop characteristic off-flavors at low levels of oxidation, require procedures that are extremely sensitive to oxidation. Thus methods of measuring the decrease in unsaturation (iodine number) or the increase in diene conjugation as a result of the reaction do not lend themselves to quality control procedures, although they have been used successfully in determining the extent of autoxidation in model systems (Haase and Dunkley 1969A Pont and Holloway 1967). 

Several methods have been introduced which express the degree of oxidation deterioration in terms of hydroperoxides per unit weight of fat. The modified Stamm method (Hamm et at 1965), the most sensitive of the peroxide determinations, is based on the reaction of oxidized fat and 1,5-diphenyl-carbohydrazide to yield a red color. The Lea method (American Oil Chemists Society 1971) depends on the liberation of iodine from potassium iodide, wherein the amount of iodine liberated by the hydroperoxides is used as the measure of the extent of oxidative deterioration. The colorimetric ferric thiocyanate procedure adapted to dairy products by Loftus Hills and Thiel (1946), with modifications by various workers (Pont 1955 Stine et at 1954), involves conversion of the ferrous ion to the ferric state in the presence of ammonium thiocyanate, presumably by the hydroperoxides present, to yield the red pigment ferric thiocyanate. Newstead and Headifen (1981), who reexamined this method, recommend that the extraction of the fat from whole milk powder be carried out in complete darkness to avoid elevated peroxide values. Hamm and Hammond (1967) have shown that the results of these three methods can be interrelated by the use of the proper correction factors. However, those methods based on the direct or indirect determination of hydroperoxides which do not consider previous dismutations of these primary reaction products are not necessarily indicative of the extent of the reaction, nor do they correlate well with the degree of off-flavors in the product (Kliman et at. 1962). 

Modification of a Published Procedure for the Determination of Picocurie Concentrations of Iodine-131 in Milk... 

Many of the tests described involve physical properties such as refractive index, viscosity or melting point of the fat, of the fatty acids or of the lead salts of the fatty acids. However, there were also many chemical tests such as Reichert, Polenske, iodine, saponification and acetyl values. These all gave information as to the composition of the fat, some information as to fatty acid composition, others as to other non-glyceride components of the fat. Thus the iodine value is a measure of unsaturated fatty acids in the fat, now obtainable in more detail from a fatty acid profile. Similarly the Reichert value is a measure of volatile fatty acids soluble in water. For most purposes this means butyric acid, and so the modem equivalent is the determination of butyric acid in the oil. The modem method for milk-fat analysis is thus carrying out the analysis in a similar way to the Reichert determination, but uses a technique that is less dependent on the exact conditions of the analysis and is thus less likely to be subject to operator error. The Reichert value could be useful, in theory, even if milk fat was not present. Lewkowitsch notes that some other oils do give high values. Porpoise jaw oil has a value almost twice that of milk fat, while some other oils also have significant values. It is unlikely that one would have come across much porpoise jaw oil even in 1904, and even less likely today. 

Iodine and Se speciation in breast milk provides an example of the use of CE in hyphenated systems with ICP-MS detection. By employing CE, Michalke and colleagues determined selenoaminocids and identified two chemical forms of iodine, I- and thyroxine, which were present in comparable amounts in milk [115-117]. Other authors used SEC and IEC for I speciation in various types of milk and infant formulae (see Table 8.3) and found I- as the main species, with the exception of breast milk and formulae. The latter were found to contain less I than commercial and human milk, and mostly as an unidentified macromolecular compound. 

P. Bermejo Barrera, M. Aboal Somoza, A. Bermejo Barrera, M. L. Cervera, M. de la Guardia, Microwave assisted distillation of iodine for the indirect atomic absorption spectrometric determination of iodide in milk samples, J. Anal. Atom. Spectrom., 16 (2001), 382-389. 

Gravimetric methods have been developed for most inorganic anions and cations, as well as for such neutral species as water, sulfur dioxide, carbon dioxide, and iodine. A variety of organic substances can also be easily determined gravimetri-cally. Examples Include lactose in milk products, salicylates in drug preparations, phenolphthalein in laxatives, nicotine in pesticides, cholesterol in cereals, and benz-aldehyde in almond extracts. Indeed, gravimetric methods are among the most widely applicable of all analytical procedures. 

The starch-iodine method has been used for determining iodide (or iodine) in natural waters [4,5,43], milk [1], and silicate minerals [3]. The extractive method has been applied in determinations of iodine in brine [44], rocks [45], and lead telluride [46]. 

Leiterer, M., Truckenbrodt, D., Franke, K. Determination of iodine species in milk using ion chromatographic separation and ICP-MS detection. Eur Food Res Technol 2001, 213, 150-153. 

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