Iodine determination in food by inductively coupled plasma mass spectrometry after digestion by microwave-induced combustion

Abstract

Iodine determination in food samples was performed by inductively coupled plasma mass spectrometry (ICP-MS) after digestion by microwave-induced combustion (MIC). Sample masses up to 500 mg of bovine liver, corn starch, milk powder, or wheat flour were completely combusted using the MIC system. Ammonium nitrate (6 mol l(-1) solution, 50 μl) was used as an aid for ignition and vessels were charged with 15 bar of O(2). The use of H(2)O, 0.9 mmol l(-1) H(2)O(2), 10 to 50 mmol l(-1) (NH(4))(2)CO(3) and 56 mmol l(-1) tetramethylammonium hydroxide was investigated as absorbing solutions, as well as the suitability of performing a reflux step after the combustion process. Digestion of food samples by pressurized microwave-assisted acid digestion, microwave-assisted extraction and conventional extraction of iodine in alkaline solution were also evaluated. Iodine recoveries higher than 99% were obtained using MIC and 50 mmol l(-1) (NH(4))(2)CO(3) or 56 mmol l(-1) tetramethylammonium hydroxide as absorbing solution and with 5 min for the reflux step. Accuracy was evaluated using certified reference materials (bovine muscle, corn bran, and milk powder) and agreement better than 97% was obtained. The limit of quantification by MIC and further ICP-MS determination was 0.002 µg g(-1). Blanks were always low and no memory effects were observed. Digestion by MIC allowed the processing of up to eight samples by each run in 25 min with high efficiency of digestion (residual carbon content lower than 1%) providing a suitable medium for further iodine determination by ICP-MS.

Bromine and chlorine determination in cigarette tobacco using microwave-induced combustion and inductively coupled plasma optical emission spectrometry

“…A reflux step can be applied after combustion, assuring an effective washing of vessel walls and holder surface, which is a great advantage over the classic combustion systems, where the cleaning step of the vessel must be performed manually. This method has been successfully applied for digestion of biological samples, 24,25 elastomers, 26 coal 27 and crude oil products [28][29][30][31][32][33] for subsequent metal and halogens determinations. In this work different cigarette tobacco samples were digested by MIC and further Br and Cl determination was performed by ICP OES.…”

Quantitative Determination of Bromine and Iodine in Food Samples Using ICP-MS

“…8 Organic Br and I compounds in bio-samples have routinely been identified by chemical techniques following their isolation, and by modem spectroscopic methods, such as by GC, 9,10 HPLC and HPLC hyphened inductively coupled plasma-mass spectrometry (ICP-MS). 8 Total halogen (Br, I) in food was analyzed by ICP-OES and ICP-MS, 11,12 and other methods. The purpose of this study was to set up a method for total Br and I analysis in bio-samples with acceptable uncertainties at levels relevant to food control, and its validation.…”

Determination of bromine, fluorine and iodine in mineral supplements using pyrohydrolysis for sample preparation

“…Techniques such as spectrophotometry, 6 potentiometry using ion-selective electrode (ISE), 7 ion chromatography, 8,9 inductively coupled plasma optical emission spectrometry (ICP OES), 10,11 and inductively coupled plasma mass spectrometry (ICP-MS) [12][13][14][15] can be employed for Br, I and F determination. Fluorine can also be determined by graphite furnace molecular absorption spectrometry, 16 ion chromatography 10,17 and capillary electrophoresis.…”