Comparison of digestion techniques for determination of iodine in milk by vapour - generation inductively coupled plasma - optical emission spectrometry
| Authors | |
|---|---|
| Year of publication | 2005 |
| Type | Article in Proceedings |
| Conference | European winter conference on plasma spectrochemistry 2005 |
| MU Faculty or unit | |
| Citation | |
| Field | Analytic chemistry |
| Keywords | iodine; ICP-OES; vapour-generation; milk |
| Description | Quantification of natural contents of iodine in milk requires sensitive methods. Limit of detection of Inductively coupled plasma optical emission spectrometry with conventional nebulization is not sufficient and mainly spectral interferences disable determination of iodine. Generation of volatile vapour of iodine to the ICP enhances sensitivity and overcome spectral interference of phosphorus. In our work two different types of decomposition techniques were investigated with consequential generation of iodine to the plasma for determination of iodine in milk. Alkaline ashing with calcium nitrate / potassium hydroxide can be followed directly by VG-ICP-OES from water leachate of ash however carbonates in ash cause spectral interference (CO molecular emission band in spectra). These were eliminated in the sample by acidification and evaporation of volatile carbon dioxide in the presence of reducing agent (sulphite). Using this procedure the spectral interference was completely removed. Low-temperature ashing in oxygen plasma was another investigated method, which is very comfortable because no additional chemicals are necessary. Generation of iodine vapour was established with oxidation mixture of sulfuric acid and hydrogen peroxide in vapour generator with gas-phase separator. Sensitivity of the system is sufficient for quantification of natural contents of iodine in milk samples. Recovery of digestion methods was verified using ICP-MS method with conventional nebulization. |
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