Application Of B-Z Chemical Oscillating Systems In Analyses Of Amino Acids And Metal Ions

Oscillating chemical reaction as a typical phenomenon of nonequilibrium and nonlinearity, has attracted considerable attention and extensive study of researchers for many years. At present, the major interests focuse on the application to analytical determination and designing new oscillator. This thesis reports the determination of cobalt ion by using malic acid- malonic acid double substrates oscillating chemical system, the qualitative and quantitative determination of L-cysteine in compound amino acids, the simultaneous determination of L-cysteine and L-tyrosine based on an oscillating chemical reaction and the determination of L-tyrosine using an oscillating chemical reaction coupled with analyte pulse perturbation technique. It includes five parts.Chapter One: IntroductionThis review summarizes the investigation progresses about some oscillating chemical reactions system and their mechanisms, and the conditions arousing chemical oscillation behaviour, the classifications of chemical oscillating systems are also introduced. Their applications in analytical determination are described. At last the perspective of chemical oscillation reactions is discussed simply.Chapter Two: Determination of trace amount of cobalt ion by using malic acid- malonic acid doube substrate oscillating chemical systemA novel kinetic method for determination of trace amounts of cobalt ion is proposed and validated based on an B-Z oscillating chemical reaction using a malic acid- malonic acid-Ce(SO4)2 - KBrO3 - H2SO4 double substrate system. This method has been successfully used to the highly sensitive determination of trace amount cobalt ions. The results show which when the concentration of cobal ion is in the range of 5.27×10-8 to 5.27×10-12 mol/L, the changes of oscillating period are linearly proportional to the negative logarithm of the concentrations of cobal ion. The sensitivity and precision of the proposed method were quite good. The limit of detection is down to 5.27×10-13 mol/L and the regression coefficient is 0.9975. The proposed method has been used to the determination of cobalt ion in vitamin B12 in injection sample successfully. This procedure is one of the most sensitive methods for the determination of metal ions using chemical oscillation reaction so far.Chapter Three: Direct qualitative and quantitative determination of L-cysteine in compound amino acid based on an oscillating chemical reactionA new method for direct quantitative and qualitative determination of L-cysteine in compound amino acid is set up based on the classical Belousov-Zhabotinskii (B-Z) oscillating reaction. A characteristic oscillating profile of L-cysteine perturbed B-Z reaction can be used to recognize its existence. And it is also found that the oscillating period and amplitude are both disturbed and increased quickly when L-cysteine was injected into the systems, and the changes in the oscillating period and amplitude are linearly proportional to the negative logarithm of the concentration of L-cysteine in a wider range of 5.36×10-4~3.35×10-7 mol/L and 7.85×10-4~3.96×10-6 mol/L, with a detection limit of 1.68×10-8 mol/L and 1.98×10-7 mol/L,and the regression coefficient is respectively 0.9934 and 0.9954 (n=9). Possible influences of other amino acids on the determination of L-cysteine are also discussed. Qualitative recognization to some substances using chemical oscillating reaction can largely expand application field of this method and correlative report has not been found so far.Charpter Four: Simultaneous determination of L-cysteine and L-tyrosine using on an oscillating chemical reactionA rapid and convenient method for the simultaneous determination of the mixture of L- cysteine and L-tyrosine is presented based upon their perturbation of the B-Z oscillating system. When the mixture of L-cysteine and L-tyrosine was injected into the Ce(IV)-catalyzed B-Z oscillating system, the change in the amplitude was directedly proportional to the logarithm of the concentration of L- cysteine and L-tyrosine over the range 1.24×10-3~1.35×10-5 mol/L and 5.36×10-4~5.74×10-7 mol/L respectively, The proposed method allows a direct simultaneous and rapid determination of the compounds with a detection limit down to 1.05×10-5 mol/L and 5.74×10-8 mol/L respectively and regression coefficients of 0.9961 and 0.9973 under the determination conditions. Finally, the possible perturbation mechanisms of the two amino acids on the oscillating reaction are also discussed. Charpter Five: Determination of L-tyrosine using a chemical oscillating reaction coupled with analyte pulse perturbation techniqueA sensitive, rapid and convenient analytical method based on sequential perturbation of the B-Z oscillating system in a continuous-flow stirred tank reactor (CSTR) is presented for determination of L-tyrosine. The results show that the changes in oscillating amplitude are linearly proportional to the–logC (where C is the concentration of L-tyrosine) in the range of 5.36×10-7 to 5.36×10-4 mol/L, with a regression coefficient of 0.9996. The limit of detection is down to 2.68×10-8mol/L. Possible mechanism of L-tyrosine perturbation on the oscillating reaction is also discussed. The proposed method has been successfully utilized to determination of L-tyrosine in a commercially available L-tyrosine sample.