Rapid Determination Of Lodine(Ⅰ) And Mercury(Ⅱ) By Catalytic Spectrophotometry

Kinetic analysis is based on the relation between the rate of chemical reactionand the concentration of reactants or catalyst. Because of its high sensitivity, lowdetection limits, simple equipment, kinetic analysis has been widely applied to theanalysis of high purity of substances, materials, biological samples and environmentalsamples to determine trace substances, such as the determination of trace element innatural water. The basic principles of kinetic analysis, rate measurement, quantitativemethod and applications in the trace element detection were described in this paper.A new method for the rapid determination of urinary iodine was developed. Themethod was based on the iodine-catalyzed oxidation of3,3’,5,5’-tetramethylbenzidine （TMB） by H₂O₂, to yield bule products. Catalyticspectrophotometric determination of urinary iodine was developed. Samplepreparation is simple. The interfering substances were removed with disposablecolumns packed with purified activated charcoal. Ascorbic acid, bilirubin, creatinineand other interfering substances in urine can be adsorbed on disposable columns.Compared with the traditional determination method of urinary iodine, this method issimple and rapid. The experiment from sample preparation to determination takes lessthan20minites. The urine did not need to be digested, and the time of samplepreparation was shortened. The iodide ion can be lost in the digestion.The recoverieswere between90.09%and111.16%, the detection limit is3.62μg/L. The resultsobtained by this method are in agreement with these obtained by national standardmethod.A rapid method for the determination of mercury （II） in water sample has beendeveloped, based on the strongly inhibition effect of Hg²⁺on urease activity. Whenthe urease activity was inhibited, the urease-catalysed urea hydrolysis reaction can be also inhibited. The pH of the urea hydrolysis reaction system also changed with thechange of Hg²⁺concentration. Phenol red was used to indicate the pH change of theurea hydrolysis reaction system. The absorbance of the reaction system was monitor-ed on UV-Vis spectrophotometer. The method was applied to the determination ofHg²⁺in drinking water and underground water samples, the recoveries of Hg²⁺rangedfrom89.00%to116.67%. Sample preparation is simple, rapid, and this method contr-ibuted to rapid detection mercury （II） on-site.