Catalytic Kinetic Determinations: Nonenzymatic

摘要: Although a catalyst does not shift the position of equilibrium but it markedly change reaction rate, because lowers activation energy providing an alternative favorable route for formation products. The reacted is regenerated and repeatedly involved in indicator reaction. When rate depends on concentration catalyst, can be determined by measuring physical properties reactants and/or products property such as absorbance, fluorescence, chemiluminescence (CL) or electrode potential system usually monitored with time. This methodology called catalytic methods kinetic–catalytic analysis. Kinetic–catalytic analysis based catalyzed reactions have progressed recently been applied to trace analyses various catalysts (element) their extremely high sensitivity, low limit detection selectivity. Several redox, ligand substitution complexation utilized development analyses. Most redox are metal ions inorganic anions having different oxidation states cobalt, copper, chromium, iron, manganese, vanadium, selenium, iodide, bromide nitrite. Oxidants capable regenerating hydrogen peroxide, chlorate, bromate, periodate dissolved oxygen. Reductants include ascorbic acid, hydroxylamine, hypophosphorous alkali sulfides, dithiothreitol tin(II). Certain substances significantly increase reactions. These referred activators defined that do catalyze enhance effect catalyst. Activators provide sensitivity selectivity methods. Such improved specificity expected eliminate preliminary separation many instances. As measurement includes time experimental variable, care needed ensure mixing reagents takes place at regular intervals obtain highly accurate results using manual procedure. disadvantages overcome flow-injection (FIA), which easily controlled varying flow solutions length coil. Kinetic–catalytic allow determination elements nanogram picogram levels (10−11 M) simple reasonable equipment. limits (DLs) order picograms per milliliter good accuracy precision almost equal those inductively coupled plasma mass spectrometry (ICPMS). The application effects titrimetry has recognized long titration involves two consecutive reactions, i.e. determinable 10−6 M ions.