Study On Novel Analysis Methods For The Determination Of Trace Arscenic And Uranium In Water Environment

Chapter 1:In this chapter,the significance,background and current situation of sanitary testing methods for arsenic and uranium in aquatic environment are introduced at home and abroad.Secondly,the basic design principles of the related technologies involved in the new detection methods in this paper are summarized,including wireless sensor method,resonance light scattering method and molecular imprinting technology and so on.Finally,the research contents and innovations of this paper are elaborated.Chapter 2:In the chapter,the arsenic（III）aptamer（Ars-3）was used as a recognition element,the signal amplification of gold nanoparticles（AuNPs）and Graphene oxide（GO）was used to establish a new wireless sensor method for the detection of trace arsenic（III）.By designing a ssDNA labeled with SH,this strand is complementary to Ars-3 to form an incomplete dsDNA.GO has strong affinity for ssDNA.When As（III）is added,As（III）can specifically bind to Ars-3 to form[As（III）-Ars-3]complex,so the SH-labled ssDNA can be captured by GO of the Magnetoelastic Sensor（MS）,resulting in a change in the vibration frequency of the MS（Δf）.The optimized assay conditions were as follows:dsDNA-AuNPs with a final concentration of 0.5μmol/L were added into a small glass tube,followed by addition of the prepared magnetic shrapnel,different volumes of arsenic standard solution,50μL of 2.0%HAuCl₄,25μL of 0.05 mmol/L AA and 12μL of CTMAB incubate at 50℃for 20 minute.The concentration of As（III）andΔf is linear in the range of 0.5³0μg/L.The detection limit of As（III）was 0.41μg/L,r=0.9922.The experiment has been applied to the determination of trace arsenic in several actual environmental water samples with relative standard deviation（RSD）less than 5.31%and the recovery rate were between 92.70%and 108.23%.The results were satisfactory.Chapter 3:A new resonance light scattering method for the determination of arsenic in water samples was developed based on the characteristics of gold nanoparticles and As（III）-aptamer（Ars-3）.The Ars-3 can be adsorbed on the surface of gold nanoparticles to prevent it from agglomerating with PDDA,and the resonance light scattering intensity of the system was weak.When As（III）was added,Ars-3 would combine with As（III）to form the binary complexes,which would lose the protection for gold nanoparticles.Then,the gold nanoparticles would be aggregated In the presence of polydiallyldimethylammonium chloride（PDDA）,resonance light scattering intensity（I）was enhanced.The resonance light scattering enhancement value（ΔI）was proportional to the amount of As,and the As can determined by the standard curve method.There was a good linear relationship between theΔI at 544.6nm and c_Ass in the range of 0.50³0 ng/mL,and the linear regression equation was?I_RLS=205.42c_As+379.99（ng/mL）,r=0.9976,The detection limit was0.34 ng/mL.The method has the advantages of good sensitivity,simple instrument and reagent,simple operation and short reaction time,and can be used for the detection of As in the actual water samples.Chapter 4:AuNPs can reduce the resonance fluorescence intensity of rhodamine 6G（Rh6G）,arsenic-specific nucleic acid aptamer（Ars-3）can block the aggregation of AuNPs and Rh6G in arsenic-free systems,and maintain the resonance fluorescence intensity of the system at a high level.When arsenic ions are present in the system,Ars-3 specifically binds to arsenic ions,AuNPs binds to Rh6G,and the resonance fluorescence intensity of the system decreases.Based on this,a new method for the determination of arsenic in water by resonance fluorescence method is established.The resonance fluorescence intensity reduction valueΔF of the system has a good linear relationship with the arsenic ion concentration of 1.0³2.0μg/L.The regression equation of the standard curve isΔF=1020.2 c+7679.7（μg/L）,and the correlation coefficient is r=0.9906.The limit is 0.50μg/L,the RSD is less than2.72%,and the recovery rate is 95.50%¹03.37%.Chapter 5:A new multiphase photocatalytic resonance fluorescence method was used to detect the content of uranium（VI）in water samples by molecular imprinting technique combined with photocatalytic resonance spectroscopy.In the system,RhG has a strong resonance fluorescence intensity.When the oxidant KBrO₃ was added to the system,the resonance fluorescence of RhG is slightly lowered.The reason may be that KBrO₃ can oxidize RhG_reded to a non-fluorescent product(RhG_ox)under strong light irradiation,resulting in a slight quenching of the resonance fluorescence of the system.When Uranyl Magnetic Chelating Adsorbent（UMCA）was added to the RhG-KBrO₃ system,the decrease in resonance fluorescence intensity was observed to be more significant,indicating that UMCA can enhance the photocatalytic activity of uranium and accelerate fluorescence quenching of the reaction system.The content of uranyl ions is inversely proportional to the resonance fluorescence intensity of the system,and the content of uranium（VI）can be detected by a standard curve method.Under the optimal experimental conditions,the change of resonance fluorescence intensityΔF and uranium（VI）in the system showed a good linear relationship in the range of 0.24⁸μg/L.The linear regression equation isΔF=79.362c+138.63（μg/L）,correlation coefficient r=0.9935,the minimum detection limit is 2.4×10^-5（μg/L）.The method has good sensitivity,simple instrument and reagent,simple operation and short reaction time,and can be used for detecting uranium（VI）content in actual water samples.