The Research On The Analytical Application Based On Chemical Oscillating System

Nonlinear chemical is different from conventional organizations,it manifests dynamic,open,flexible and non-linear characters and is an organizational form far from the trend of balance.Oscillating chemical reaction as a typical phenomenon of nonequilibrium and nonlinearity,has attracted considerable attention and extensive study of researchers for many years.The well-known oscillating chemical systems are the Belousov-Zhabotinskii(B-Z)reaction and the Bray-Liebhafsky reaction.The Briggs-Rauscher(B-R)reaction can be considered a hybrid between the B-Z reaction and the B-L reaction.The B-R oscillating system consists of the potassium iodate and oxidation of an organic substrate(in general,malonic acid(MA)or its derivatives)by acidic iodate in the presence of H2O2 and with the macrocyclic nickel(?)complex([NiL](ClO4)2 as catalyst.The B-Z oscillating system consists of the Sodium bromate,sulfuric acid and malonic acid as substrate by Cerium sulphate as catalyst.In this paper,the application of B-R oscillation system and B-Z oscillation system in analysis and detection are introduced.The paper contains four chapters,first chapter put forward the basic concepts of nonlinear chemistry and the typical nonlinear chemical phenomena.The development of nonlinear chemical process is briefly introduced,and the application of nonlinear chemical oscillation system in analytical detection is also described.The historical background and progress in the oscillating reactions in both research and in mechanism have been discussed.The second chapter designed a new analytical method for the determination of 2,6-di-tert-butyl-4-methylphenol by the sequential perturbation caused by different amounts of BHT on the BR oscillating chemical system involving the Ni(II)-catalyzed oscillating reaction between hydrogen peroxide,potassium iodate and malonic acid in a acidic medium is proposed.This method for the detection of antioxidants BHT based on the inhibitory effect,at temperature of 4±0.5 under pH of 2(pH of the stomach fluid),containing macrocyclic Ni-complex as catalyst,[NiL](ClO4)2.The ligand L in the complex is 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraaza cyclotetradeca-4,11-diene.It relies on the relationship between inhibition time(tin)of the chemical system and the concentration of 2,6-di-tert-butyl-4-methylphenol.As concentration of BHT within system increase which the inhibition time is increased.It was found that the inhibition time that produced by the addition of BHT is directly proportioned to the concentration of BHT.Thus a new system for the determination of BHT based on the inhibitory effect is introduced.This method perform well in the determination of BHT.The calibration curve fits a second-order polynomial equation very well when the concentration of 2,6-di-tert-butyl-4-methylphenol over the range 1.95×10-7 mol/L?6.25×10-1 mol/L(r = 0.99905),whereas,when the concentration of 2,6-di-tert-butyl-4-methylphenol over the range 6.25×10-6 mol/L?1.56×10-5 mol/L,the calibration curve is linearly proportional,with the regression coefficient is 0.98666.This new method consists inexpensive reagents and apparatus are commonly used in all chemical laboratories,what more the precision is excellent,the relative standard deviation of 10 parallel determinations was 3.59%for 3.125×10-6 mol/L BHT.The effect of influential variables,such as the concentration of reaction components and injection point were studied.Some aspects of the potential mechanism of action of 2,6-di-tert-butyl-4-methylphenol on the BR oscillating system are discussed in detail.In chapter three,a novel method for evaluating antioxidant capacity of synthetic polyphenolic compounds was studied by using their inhibitory effects on a Briggs-Rauscher(BR)reaction with a macrocyclic complex[NiL](ClO4)2 as catalyst.The ligand L in the complex is 5,7,7,12,14,14-hexemethyl-1,4,8,11-tetraazacyclo tetradeca-4,11-diene.Addition of antioxidants into BR system resulted in quenching and subsequently regenerating oscillations.This paper introduce a method to evaluation three polyphenolic compounds use BR oscillation reaction,use constant current system product by vernier,compared to instrumental analysis,the oscillating chemical reaction as an analytical tool has some advantages such as simple in set-up,the sensor can easy-to-use collection dynamic current,easy for the operation,largely linear range and so on.The addition of antioxidants to a BR system should quench the oscillation,with the inhibition time depending linearly on the concentration of the antioxidant added.The excellent recovery range from 97.86%to 104.27%.So a quantitative measurement of antioxidant of Butylated hydroxytoluene(BHT),Butylated hydroxyanisole(BHA)and Propyl gallate(PG)was built.When different types of antioxidant with same concentration were used within a system,the system produced different inhibition time(tin).An effective method was thus established by evaluating of the antioxidant capacity of BHT,BHA and PG.Furthermore a reaction mechanism based on the FCA model has been proposed.Forth,we introduced a method to identify three isomers,Resorcinol,Hydroquinone and Catechol by employing a B-Z oscillator(H2SO4-NaBrO3-malonic acid-Ce(SO4)2)in the last part.The repetition experiments proved that these three isomers could have markedly different perturbation effects on Ce(SO4)2-catalyzed B-Z oscillator,so a new method could be expected to exploit this behavior to identify Resorcinol,Hydroquinone and Catechol.Furthermore,a reaction mechanism based on several experiments(like cyclic voltammetry and UV)and FKN model has been proposed.The experimental results indicated that addition of Resorcinol,Hydroquinone and Catechol could affect the profiles of potentiometric oscillations,but their changes in the profiles are greatly different.When Hydroquinone or Catechol was injected into the oscillating system,there was an initial spiking of the oscillations.While Resorcinol was injected into the dynamic mixture,the oscillatory system responded to the perturbation with accompanying by quenching of oscillations before the regeneration of oscillations.The perturbation of involves inhibition time,whereas the perturbation of Hydroquinone or Catechol does not.Hence these three positional isomers could be distinguished by using their different perturbation effects on a B-Z dynamic system in the range of 2.5×10-6?1.50×10-3mol/L.