Double Wavelength Double Indicator Application Of Catalytic Kinetic Spectrophotometry In The Analysis Of The Trace Elements

In this paper, several dual-indicator catalytic kinetic reaction systems were studied. In consideration that Co²⁺、Fe³⁺、Mn²⁺ etc. have catalytic action to dual-indicator reaction systems, according to the ratio between the reaction rate and catalyst concentration, dual-wavelength dual-indicator Catalytic kinetic spectrophotometry method were used in Co²⁺、Fe³⁺、Mn²⁺etc. measurement. The experiment studied The best dosage of reagents,reaction medium experiments of the reaction temperature and the influence of experimental time on the reaction rate, and working curves are given according to the results of the experiment. The main contents are as follows:1. In chapter three, a new dual-wavelength dual-indicator catalytic kinetic spectrophotometric method to detect the trace of Co²⁺ was studied.This method was based on Co²⁺ catalyzing oxidation of orange G and m-cresol purple by hydrogen peroxide in NH3-NH4 Cl medium. The absorbances of the catalytic and noncatalytic systems were measured at500nm1λ= and 575nm2λ=, respectively. Under the optimum conditions, the linear range of determination is Lg 0.1¹.0μμmLm g and the detection limit is 100.35μgmL-×. The method was applied for the determination of trace Co²⁺ in vitamin B12 injection sample and the recovery was 95.8¹02.8%.2. In chapter four, a new dual-wavelength dual-indicator catalytickinetic spectrophotormetric method is developed for the determination of trace Mn²⁺. The method was based on Mn²⁺ catalyzing oxidation of acid fuschin and methylene blue by potassium periodate HAc-NaAc medium which pH=4.50. The results showed that the detection limit areμgmL41011.1-×. This method has been successfully used to the determination of Mn²⁺ in Tea samples.3.In chapter five, the determination of trace Mn（Ⅱ） with orange G and potassium periodate oxidation of malachite green system were studied. By using HAc-Na Ac medium which pH=4.6, Mn（Ⅱ） catalyzing oxidation of orange G and malachite green at the same time.. By measuring the505nm1λ= and 595nm2λ= wavelength catalytic system and the non-catalytic system change in absorbance and established a dual wavelength and dual-indicator catalytic Trace Mn（Ⅱ）.. The detection limit are 1039.14μgmL-×.This method has the advantages of simple operation, which can be used to measure the trace manganese Mn（Ⅱ） in the water. The results of the experiment was satisfactory.4.In chapter six, the method of oxidation with hydrogen peroxide rhodamine B and methylene blue system determination of trace Fe³⁺ is studied. In pH=3.14 HNO3 acidic liquid medium, the trace of Fe³⁺ can catalyze the oxidation of hydrogen peroxide rhodamine B and mheethylene blue.By measuring the change of absorbance when 555nm1λ= and663nm2λ= wavelength in both catalytic system and non-catalytic system, a new method of dual-wavelength dual-indicator catalytic kinetic spectrophotometric determination of trace Fe³⁺ were proposed. Thedetection limit is 1091.14μgmL-×.This method has the advantages of high sensitivity, it can be used directly in the determination of trace Fe3 + in the rain.This paper shows that dual-wavelength dual-indicator catalyst system is an effective method in the determination of trace element.Because of its advantages such as high sensitivity and wide scope,dual-wavelength dual-indicator catalyst system has a certain value in the scientific research and practical application.