| Thorium is a kind of radioactive elements that is often used as the reactor fuel and widely used in industry.However,the radioactivity and toxicity of thorium has a great threat to human health,so the detection of thorium ions in biological and environmental samples has drawn great attention of the researchers.Among the various analyticalmethods that have been developed for the detection of thorium ions,thefluorescence analysis methodbecause of the advantages of simpleness,rapidity,low cost,high sensitivity and selectivity has become a hot spot about developing new analysis methods for thorium ions determination.In this paper,fluorescent probes based on salicylaldehyde acyl hydrazoneschiff base were synthesized and the new fluorescence analysis methodfor detecting thorium ions was established just by thefluorescence analysis technology.This thesis was conducted mainly in the following three aspects:1.The definition,synthesis and application of Schiff base were described briefly,and a systematic introduction of the fluorescence analysis method and the existing analysis methods for detecting thorium ions were given.2.A fluorescent probeL1 based on Schiff base was synthesized by the condensation reaction of salicylaldehyde and propanedioyl dihydrazide.The obvious enhancement of the fluorescence intensity of L1occurred after the addition of Th4+ions in the V?DMF?:V?H2O?=1:1 test medium.The best condition for the probe L1 recognizing Th4+ions was determined by discussing the influence of pHvalue,response time,ion concentration and coexistence ions onthefluorescent propertiesof L1responding Th4+ions,and the fluorescence analysis method for Th4+determination was established.Experimental results showed that the probe L1had good selectivity for Th4+ions,at pH=2.5,in the V?DMF?:V?H2O?=1:1 test medium,a good linear relationship between the fluorescence intensity of the probe and Th4+concentration in the range of01.1×10-4 mol·L-1was presented?R2=0.98?with the detection limit of9.23×10-8 mol·L-1.The analysis method was applied to practical water samples for detecting thorium ions with ideal effect.3.A fluorescent probeL2 based on 3-Allylsalicylaldehyde was synthesized.The fluorescence intensity became strong distinctly after L2reacting with Th4+ions.The optimum p H value?pH=2.5?and most appropriate time?6 min?were confirmed throughthe fluorescence spectra of the probeL2 responding Th4+ions before and after.In DMF:H2O=1:1?v/v,pH=2.5?test medium,the influence of Th4+concentration and interfering metal ions on thefluorescent properties of L2 responding Th4+ions was discussed and the fluorescence analysis method for Th4+determination was established.Experimental results showed that interfering metal ions had no noticeable influence on the probeL2detecting Th4+ions,a good linear relationship between the fluorescence intensity of the probe and Th4+concentrationin the range of0.21.1×10-4 mol·L-1was appeared?R2=0.98?with the detection limit of2.53×10-7mol·L-1.The analysis method was applied to practical water samples for detecting thorium ions with ideal effect. |
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