Flow Injection-Spectrophotometric Determination of Trace Amounts of Iodide by Its Catalytic Effect on the 4,4-Bis(dimethylamino)-diphenylmethane-Chloramine T Reaction

Abstract

A flow injection analysis method is proposed for the spectrophotometric determination of trace amounts of iodide based on its catalytic effect on the oxidation of 4,4'-bis(dimethylamino)diphenylmethane (tetrabase) by Chloramine T in a weakly acidic solution. Iodide in water samples can be determined at a sampling rate of 85 h-1 with 300 µl sample injections. The detection limit is 0.1 µg 1-1 and the calibration graph for iodide is linear up to 2.tg 1-1, showing a slightly negative deviation in the higher concentration range. The relative standard deviations are 2.8 and 0.8% for 0.40 and 4.0 µg 1-1 iodide, respectively. Although free iodine shows a somewhat lower catalytic effect and iodate no catalytic effect up to at least 50 µg 1-1 as iodine, these species show the same effect as iodide upon being reduced with thioacetamide in an acidic solution. The procedure has been applied to the determination of iodide in natural water samples as well as iodine impurity in both distilled and redistilled water samples. It has also been used to examine iodine contamination in ambient air.

Rice (Oryza sativa L.) roots have iodate reduction activity in response to iodine

“…Iodate reduction activity was evaluated by the amount of I − reduced from IO − 3 by 1 g (FW) of excised roots per hour. I − concentration in the buffer was determined by 4,4′-methylenebis( N,N -dimethylaniline)-chloramine T reaction (Yonehara et al, 1991). To evaluate the net I − concentration reduced from IO − 3 by excised roots, the concentration of I − in the IO − 3 -free buffer incubated with excised roots was also determined as I − derived from excised roots during incubation, and subtracted from I − concentration in the IO − 3 buffer incubated with excised roots.…”

Determination of Iodide in Brines by Membrane Permeation Flow Injection Analysis†

“…The sensitivity is not as good as other flow injection methods, e.g., a catalytic spectrophotometric flow injection method has a reported detection limit of 0.1 mg l 21 iodide. 11 The method described here is, however, highly selective to iodide, as no matrix effects or interferences other than sulfide were found. The flow injection method is simpler, easier to use and more rapid than the manual batch methods.…”

“…Manual methods for iodide determination are usually tedious; however, flow injection analysis represents an interesting method for automation. 5 Several flow injection methods for determination of iodide based on spectrophotometric, [6][7][8] potentiometric 9,10 and catalytic spectrophotometric detection 11,12 have been reported. Motomizu and Yoden 13 reported a tubular microporous PTFE membrane that was applied to the permeation of chlorine, bromine and iodine.…”

Kinetic Determination of Total Iodine in Urine and Foodstuffs Using a Mixed Acid as a Pretreatment Agent

“…Yonehara et al investigated the contamination of iodine from ambient air in the laboratory. 8 They reported that 50 cm 3 of pure water in a beaker caused iodine concentration, even after several minutes of standing time, and that the concentration became progressively higher with prolonged standing.…”