Determination of Iodine in Milk and Oyster Tissue Samples Using Combustion and Peroxydisulfate Oxidation

Abstract

Two methods are described for the preparation of samples for total iodine measurement in biological matrices. In the first method, the samples were combusted in a stream of oxygen to release iodine that, subsequently, was trapped in a solution as iodide. The second method is a new approach in which the samples were oxidized in a basic solution of peroxydisulfate. In this case, the iodine was retained in solution as iodate. Total iodine was measured by gas chromatographic analysis of the 2-iodopentan-3-one derivative. The methods were tested using Standard Reference Materials (SRMs) 1549 Non-Fat Milk Powder, and 1566a and 1566 Oyster Tissue. Also, KI and KIO3 were used for testing the procedures. The results obtained for the SRMs, given as average +/- standard deviation in micrograms g-1, were: 3.39 +/- 0.14 and 3.40 +/- 0.23 for SRM 1549; 4.60 +/- 0.42 and 4.51 +/- 0.45 for SRM 1566a; and 2.84 +/- 0.16 and 2.76 +/- 0.06 for SRM 1566; values corresponding to combustion and wet oxidation, respectively. Overall, the absolute recoveries varied between 91 and 103%. These methods can also be used in the preparation of targets for the measurement of 129I using accelerator mass spectrometry.

Analytical methods for the determination of halogens in bioanalytical sciences: a review

“…In addition to these methods, some devices using a tube-shape furnace combustion have been applied to combustion of organic samples [62]. Some manufacturers, such as Analytik Jena (multi X® 2500 and multi EA® 5000) and Antek® (MultiTek), have developed commercial furnace combustion systems for the decomposition and analysis of petroleum products and related matrices, but few applications can be found for digestion of biological samples and further determination of halogens [62,116].…”

“…Regarding the extraction methods, the recoveries for iodine are generally low, probably owing to the presence of insoluble iodine compounds, especially because iodine is covalently bound to biological tissues, thus requiring a decomposition step before extraction [116]. In some cases, when microwave-assisted digestion is used, the addition of small volumes (0.1-0.5 mL) of HClO 4 in combination with concentrated HNO 3 can avoid losses of volatile iodine species [55,59].…”

A Review of Spectrophotometric and Chromatographic Methods and Sample Preparation Procedures for Determination of Iodine in Miscellaneous Matrices

“…The results obtained for the SRMs, given as average +/-standard deviation in μg/l, were: 3.39 +/-0.14 and 3.40 +/-0.23 for SRM 1549; 4.60 +/-0.42 and 4.51 +/-0.45 for SRM 1566a; and 2.84 +/-0.16 and 2.76 +/-0.06 for SRM 1566; values corresponding to combustion and wet oxidation, respectively. Overall, the absolute recoveries varied between 91 and 103% (Gu et al, 1997). …”

Rapid acid digestion and simple microplate method for milk iodine determination

“…The high lipid content of milk can potentially cause problems in spectrophotometric readings, so a mineralization step prior to analysis is essential. This is a critical step because during the mineralization step, iodine can easily be lost by volatilization (9). All reported methods have a digestion or ashing step that uses alkaline media and high temperature (10).…”