| The ion-selective electrode determine concentration of ions,it need not through chemical score.It is a kind of analytical method that can rapidly determine sample continuously with simple structure,simple handled,wide potentiometric response range and highly sensitive.It has been applied in many departments of industry and agriculture and science technology.In recent years,design,synthsis and application of highly selective and sensitive neutral carriers are main research subjects in the ion-selective electrode studies.It is one of the most important of the research area of the potentiometric methods of the electroanalysis and of the organic or organometallic chemistry.This thesis focuses on seeking design and synthsis of novel metallic complexes and its used as carriers in ion-selective electrode.The proposed electrode try to applied to direct determination for anions and cations in sample..Part 1 Study on Thiocyanate Electrode Based on Glycine Schiff Base Trinuclear Copper(Ⅱ) Complex as Neutral CarriersA new thiocyanate PVC membrane electrode based on 3-carboxysalicylidene glycine Schiff base trinuclear copper(Ⅱ) complex as neutral carrier is developed,which displays an anti-Hofmeister selectivity sequence:SCN-＞ClO4-＞I-＞Sal-＞NO3-＞NO2-＞F-＞SO4-＞Br-＞SO3-＞Cl-.The electrode exhibits Nernstian potential linear range to thiocyanate from 5.6×10-6 mol/L to 1.0×10-1 mol/L with a detection limit 2.0×10-6 mol/L and a slope of -56.3 mV/dec in phosphate buffer solusion(pH5.0) at 25℃.The response mechanism is discussed in view of the AC impedance and IR spectroscopic techniques.The electrode based on trinuclear copper(Ⅱ) compound was used to determine the thiocyanate content in waste water with satisfactory results.Part 2 Potentiometric Iodide Selectivity of Polymer-Membrane Sensors Based on Co(Ⅱ) Triazole DerivativeThe 2-amion-5-mercapto-1,2,4-triazole cobalt(Ⅱ)[Co(Ⅱ)AMETR]was used as a new carrier for preparing polymeric membrane selective sensor which exhibited high affinity for iodide ion.The effects of membrane composition,pH,the influence of lipophilic ion additives and plasticizer on the response characteristics of the sensor were investigated.The sensor showed a near Nernstian slope of -56.6 mV/decade for I- ion over a wide concentration range from 8.5×10-7 to 1.0×10-1 mol/L with a low detection limit of 5.1×10-7 mol/L The sensor has a fast response time and could be used over a wide pH range of 2-8.The response mechanism is discussed in view of the A.C impedance technique.The sensor was successfully applied to direct determination of iodide content in environmental water samples and mouth wash samples.Part 3 Potentiometric detection of trace Cr(Ⅲ) at a carbon paste electrode based on organically nanoporous silica gelA novel carbon paste electrode(CPE) has been constructed with 2-acetylpyridine modified nanoporous silica gel(APNSG) acting as both the paste binder and a reactive material facilitating the electrocatalytic detection of chromium(Ⅲ).The electrode with APNSG proportions of 7.5%(W/W) exhibits linear response to Cr(Ⅲ) over a wide concentration range 1.0×10-8 to 1.0×10-3 mol/L with Nemstian slope of 19.8 mV/decade. The detection limit of this electrode is 8.0×10-9 mol/L.The electrode present a response time of～55s,relatively long life time,high sensitivity toward Cr3+ ion in comparison to other common cations.The potentiometric response are independent of the pH of the test solution in the pH range 1.5-5.0 for CPE.The response mechanism is discussed in view of the A.C.impedance technique.The proposed electrode was successfully applied to direct determination in food samples. |
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