Sandell-Kolthoff reaction

A low-cost assay of iodine in foods and urine can be performed using catalytic spectrophotometric methods, namely those based on the Sandell—Kolthoff reaction. These methods, however, are not optimal for determination of the lower range of iodine levels occurring in foodstuffs, because of possible interference. 

The level of UI was determined using the Sandell-Kolthoff reaction, which was preceded by the alkaline... 

The median urinary iodine (MUI) concentration provided a measure of the current nutritional status of iodine. MUI was performed in spot urine samples obtained from all mothers and their neonates 5 days after delivery, by using the Sandell—Kolthoff reactions. Decreased MUI excretion of both neonates with hypothyroidism and their mothers was classified as mild-to-moderate iodine deficiency according to the WHO criteria. The mean total thyroid volume (TTvol) of the neonates and their mothers was increased on ultrasonography, whereas no palpable thyroid tissue was detected on physical examination (Table 65.3). 

The laboratory analyses were performed by the Institute of Clinical Pathology and Medical Research (ICPMR), Laboratory Endocrinology Department at Westmead Hospital in Sydney, using the Ohashi microplate method (Ohashi et at, 2000), based on the Sandel—Kolthoff reaction. This laboratory complies with ISO/IEC 17025 under the accreditation scheme of the National Association of Testing Authorities and the Royal College of Pathologists of Australasia. 

Interesting research into iodine content in human thyroids was also conducted by Zabala et al. (Zabala et al., 2009). Their study focuses on the determination of iodine content in healthy thyroid samples on male population from Caracas in Venezuela. The authors aimed at establishing a baseline of iodine content in thyroid glands and hence to comjjare the iodine thyroid concentration of the Venezuelan population with other countries. Male pxist-mortem individual samples were analyzed using a spectrophotometric flow injection method, based on the Sandell-Kolthoff reaction. The median intrathyroidal iodine concentration was 1443+/-677 pg/g (wet weight), ranging from 419 to 3430 pg/g, which corresponds to a median of total iodine content of 15+/-8 mg (ranging from 4 to 37). These results were... 

Another study described simple photometric determination of the iodine concentration in the thyroid tissue of small animals. Again, the method was based on the well-known catalytic Sandell-Kolthoff reaction. Prior to the analysis, the tissue was digested in a mixture of sodium chlorate and perchloric acid at 100 degrees C. Using this manner of digestion between 94 and 110% of iodine in the sample was recovered. Comparison with the neutron activation analysis showed excellent agreement of the obtained values (Tiran et al., 1991). 

Bllek, R., Bednar, J. Zamrazil, V. (2005). Spectrophotometric determination of urinary iodine by the Sandell-Kolthoff reaction subsequent to dry alkaline ashing. Results from the Czech Republic in the period 1994-2002. Clin Chem Lab Med. Vol.43, No.6, pp 573-580, ISNN1434-6621... 

Stoic, V. (1961). Interference of Certain Ions with the Catalytic Action of Iodine in the Sandell-Kolthoff Reaction Fresenius J Anal Chem, Vol.183, No.4, p>p262-267, ISSN 0937-0633... 

Tiran, B., Wawschinek, O., Eber, O., Beham, A., Lax, S. Dermelj, M. (1991). Simple Determination Of Iodine In Small Specimens Of Thyroid Tissue. Exp Clin Endocrinol, Vol.98, No.l, pp 32-36, ISSN 0232-7384 Trokhimenko, O.M. Zaitsev, V.N. (2004). Kinetic Determination of Iodide by the Sandell-Kolthoff Reaction Using Diphenylamine-4-Sulfonic Acid. / Anal Chem., Vol.59,pp 491-494, ISSN 1608-3199... 

Although kinetic methods of analysis are of special significance to clinical and pharmaceutical analysis in relation to enzymatic methods, they are equally applicable to nonenzymatic processes. Table 7 shows the most salient contributions reported in this respect over the past few years. Most of the clinical determinations shown have been performed on blood and/or urine samples and have involved inorganic or organic ions in similar proportions. On the other hand, pharmaceutical determinations have chiefly been concerned with organic substances. The Sandell-Kolthoff reaction has by far been the most commonly employed for the analysis of biological samples, so much... 

I agree with Dr. Koutras. It is not so easy to estimate the iodine concentrations in foodstuffs. It requires the use of the Sandell-Kolthoff reaction, which is not too difficult. The most important difficulty is to assess the importance of potential losses of iodine during the extraction procedures. 

Spectrophotometric analysis continues to be one of the most widely used analytical techniques available. Kinetic spectrophotometric methods, which are based on the reaction, found by Sandell and Kolthoff (1934) set the foundation for the development of different methods for the determination of iodine in environmental samples (mostly water). The said reaction proceeds according to the following equation (1) ... 

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. 

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