Inhibition Kinetic - Spectrometry Applied Research

The kinetic analytic method is based on the relationship between substance concentration and reaction velocity. There are several detection techniques available for kinetic spectrometric methods such as spectrophotometry, spectrofluorimetry and chemiluminesce. Moreover catalyzed-kinetic methods of analysis arewidely used for higher sensitivity, the mechanism is based on that some substance can catalyze or inhibit indication reactions.for example oxidation reaction, complex reaction and so on. Usually most indication reactions can be catalyzed by metal ions, while nonmetal ions and organic substances can inhibit most indication reactions. In this paper we mainly study determination of nonmetal elements and organic substances by inhibition kinetic spectrometry. The major contents are described as follows:1. Determination Iodide in Kelp by Kinetic Spectrophotometry and SpectrofluorimetryTrace amounts of iodide were determined by kinetic spectrophotometry and spectrofluorimetry,which was based on its inhibition effects on the redox reaction between rhodamine B (RhB) and KBrO3 in H2SO4 medium in 45±0.5℃for 15 minutes. The determination signal difference (△A,△F) between inhibited reaction and non-inhibited reaction is linear with the concentration of iodide. The linear ranges were 2.0-6.0 ng/mL and 1.0-6.0 ng/mL and the detection limits were 0.06 and 0.07 ng/mL respectively. The interference ions on iodide determination were also studied. The method was simple and selective; it has been applied satisfactorily to the determination of iodide in kelp2. Inhibition Kinetic Spectrometric Determination of Trace Se(IV) Using Oxidation of bromopyrogallol red with KBrO3A new inhibition kinetic-spectrohpotometric method for the determination of trace Se(IV) has been proposed. It was based on the Se(IV) which could inhibit the redox reaction between KBrO3 and bromopyrogallol red (BPR) in HCl medium in room temperature. The absorbance difference (△A) between inhibited reaction and non-inhibited reaction was linear with the concentration of Se(IV).△A was invariable in 30 minutes, the absorbance can be determinated in some time.Under optimum conditions, calibration curve was linear in the range of 4.0-12.0 ng/mL, with the detection limit as low as 0.8 ng/mL (regression coefficient = 0.999).The regression equations was△A = 0.04233 + 0.01738C (ng/mL). It has been applied satisfactorily to the determination of Se(Ⅳ) in foodstuff.3. Determination of Trace o-dinitrobenzene by Flow Injection Inhibition-Kinetic SpectrometryA new analytical method was developed for the determination of trace amounts of o-dinitrobenzene by flow injection analysis (FIA). The method was based on its inhibition effects on the reaction between methyl red and potassium bromate in HCl medium at room temperature. The absorbance difference (△A) between the inhibited reaction and the uninhibited reaction was linear with o-dinitrobenzene concentration. Under the optimum conditions, the liner range and detection limit was 0.0- 4.5ng/mL and 0.26 ng/mL (regression coefficient = 0.9998), respectively. The sample throughout was achieved 32/h. The linear regression equation is△A = -0.01228 + 0.03571C (ng/mL). Foreign substances effects were also investigated, Hg2+, Ca2+, Pb2+, Mn2+ interfere.4. Determination of Trace Hydroquinone by Inhibition Kinetic-Spectrometry Using Surfactant as Sensitized ReageantA new inhibition kinetic-spectrohpotometric method for the determination of trace hydroquinone has been proposed. It was based on the hydroquinone which can inhibit the catalysis of Fe(Ⅲ) in the H2O2 and H2SO4 system. When the Triton X-100 microemulsion was added, the sensitivety was increased remarkably. The kinetic behaviour of this reaction was investigated. The detection limit of the method was 0.97×10-7 mol/L. And the linear range of the determination was 0.6-2.0μg/L hydroquinone. It has been applied satisfactorily to the determination of trace hydroquinone in waste water.