Studies On Sequential Injection Spectrophotometry For The Determination Of Toc And Molybdenum In Environmental Water

In this dissertation, a sequential injection analysis system combined with gas diffusion separation using spectrophotometry detection was developed for the determination of TOC in environmental water, and a catalytic spectrophotometric sequential injection analysis method was described for the determination of molybdenum in environmental water. Satisfactory results were obtained.The first section of the dissertation concerned the reviews on the sequential injection analysis and spectrophotometry, principle, characteristics and the latest applications of sequential injection analysis with spectrophotometry in environmental analysis area.The second section concentrated on a gas diffusion sequential injection system for the determination of TOC with spectrophotometry in environmental water, based on color-changing of indicator in an acidic medium. The introduction of the gas diffusion separation system eliminated the influence of the unvolatile matrices. The sampling sequence, the concentrations and volume of reagent and sample, the flow rates were optimized by univariate approach. The linear range was 5.0～120.0/μg/mL for 250μL of sample and the detection limit was 2.9μg/mL. The recoveries and the RSD (n=11) were 92.4～107.2% and 0.9%, respectively.In the third section, the SI system was explored to determine molybdenum in environmental water with spectrophotometry which was based on the catalytic action of molybdenum on the oxidation of iodide by hydrogen peroxide in acidic medium. The linear range was 2.0～300.0μg/L. The determination limit of 1.19μg/L molybdenum was obtained, with the precision (RSD) of 0.6%(n=11), while the recoveries were 95.2～105.2%.