Simultaneous Determination Of Iodine Research Articles

Voltammetry behavior of iodine and selenium on new organo-modified electrodes: Development of a procedure for the determination of iodine and selenium

The voltammetry behavior of iodine and selenium has been studied on new organo-modified electrodes. The conditions have been proposed for the measurement of the analytical signals of iodide and selenium ions on a silver electrode modified by aryl diazonium tosylates containing an amino group in the presence of a 0.1 M solution of N2H4 · H2SO4 (pH 2–3) without oxygen removal. A new approach and a procedure have been developed for the simultaneous determination of iodine and selenium in tap, drinking, and mineral waters using the organo-modified electrode. The analytical range is from 0.003 to 1.5 mg/L for iodide ions and from 0.003 to 2.0 mg/L for selenite ions.

Simultaneous determination of iodine, bromine, selenium and arsenic in geological samples by inductively coupled plasma mass spectrometry

The feasibility of determining trace iodine, bromine, selenium and arsenic simultaneously in geological samples by inductively coupled plasma mass spectrometry (ICP-MS) was investigated. The samples were mixed with flux (sodium carbonate and zinc oxide), sintered at 650 °C for 40 min in a muffle furnace and then dissolved in hot water. The cations were separated from the sample solution by using a cation-exchange resin. The analyte anions were determined by ICP-MS directly. The signal responses for the different anion species in different solution media were assessed. The sintering temperature, holding time, and amounts of flux and cation-exchange resin were optimised. The ion signal intensity of I− in nitric acid was much higher than that of IO3− and IO4−. In addition, the observed I− signal in nitric acid was not stable. Weak acid solution or dilute ammonia solution was found to be a suitable medium for determination of these elements. Ammonia solution is also effective in eliminating the memory effect of iodine and bromine. The method was applied to the determination of trace Br, I, Se and As in a series of Chinese geological reference materials (GRM, soils and stream sediments). Most of the results were found to be in reasonable agreement with the certified values. The limits of quantitation for Br, I, Se and As were 0.15, 0.03, 0.004 and 0.04 µg g−1, respectively. Precision was between 0.8 and 2.8% RSD. It was shown that the method has great potential for the routine determination of total iodine, bromine, selenium and arsenic in geological samples.

Simultaneous determination of iodine and selenium in biological samples by radiochemical neutron activation analysis

Regarding the favourably sensitive nuclear characteristics of iodine and of selenium but the very different half lives of their induced nuclides 128I and 75Se, a radiochemical neutron activation analysis method for simultaneous determination of these elements in a single sample was developed. It is based on the double irradiation LICSIR technique — Long Irradiation for Se (40h), Cooling (a week or more), Short Irradiation for iodine (1–15 min) with following Radiochemistry. After the second short irradiation, the sample is ignited in an oxygen flask and iodine and selenium are sequentially and selectively extracted as elemental iodine and 5-nitro-2,1,3 benzoselena diazole chelate. With the described method biological samples were analysed and the reliability of the results was checked by the analyses of different standard reference materials. Good agreement with certified values and high radiochemical purity of the spectra show the applicability of the radiochemical separation developed.

Determination of iodine and bromine in plasma and urine by inductively coupled plasma mass spectrometry

The simultaneous determination of iodine and bromine in plasma and urine by inductively coupled plasma mass spectrometry, using a Nermag prototype instrument, is described. The sample preparation involves only a 10-fold dilution with a diluent containing europium as an internal standard followed by direct nebulisation in the plasma. The iodine, bromine and europium ions are measured at m/z = 127, 79, and 153, respectively. The sensitivity of the method, with detection limits of 1.6 and 52 micrograms l-1 for iodine and bromine, respectively, is satisfactory for clinical applications. The calibration graphs were linear over the ranges 0-400 micrograms l-1 and 0-40 mg l-1 for iodine and bromine, respectively, which are wide enough for most assays. The recoveries were close to 100% with coefficients of variation of less than 3%. The within-day and between-day reproducibility was about 5%. The concentrations of iodine and bromine in the plasma of 26 healthy individuals were 58 +/- 12 micrograms l-1 and 4.1 +/- 0.9 mg l-1, respectively. The amounts of iodine and bromine eliminated in urine were 94 +/- 97 micrograms per 24 h (range 27-403 micrograms per 24 h) and 3.6 +/- 1.7 mg per 24 h, respectively. These results are in agreement with reported values.

Simultaneous determination of iodine and iodide by potentiometric titration

ヨウ化カリウム溶液を,4N以上の塩酸の存在で,ヨウ素酸カリウム標準液で電位差滴定すると,2個のジャンプを持つ滴定曲線が得られる.その第1段はI--e→I0,第2段はI0-e→I+の反応に正確に対応し,これによって0.14～0.014Mのヨウ化カリウムを精度よく定量することが可能である.この方法を利用してヨウ素,ヨウ化カリウムの混合溶液につき,1回の滴定を行なって,成分のそれぞれを同時定量することができた.ヨウ素25mg,ヨウ化カリウム90mgについて誤差それぞれ0.2%,0.4%であった.

Simultaneous determination of iodine and bromine in urine by neutron-activation analysis

Neutron-activation analysis was used for the simulataneous determination of iodine and bromine in urine. The activated iodine and bromine were separated by radiochemical methods. The 0·46 MeV and 0·55 MeV peak areas of 128I and 82Br, respectively, were measured by means of a multi-channel analyser. The amounts of iodine and bromine were found to be of the order of 10–7 and 10–6 g ml–1 of urine, respectively, for normal human beings of different ages.