流动注射分析用新型钆离子电极

功能高分子为活性材料,加热压片,制成新型钆电极。其性能较PVC式钆离子选择电极为优。取钆电极膜片制成流通式钆电极,与流动注射仪联用,测得电极斜率59mV,与静态响应相似。每次进样500μl,测定频率每小时60～100次。操作简单,重现性好。     

用碘离子选择性电极测定砷(Ⅲ)

砷是自然界中普遍存在而且对人体有毒的化学元素之一 ,目前分析砷的方法很多[1,2 ] ,本文用碘离子选择性电极间接测定砷 (Ⅲ )的含量 ,方法操作简单 ,结果可靠 ,检出限可达到 6.2 5× 1 0 -7ｍｏｌ·Ｌ-1。1　试验部分1 .1　主要仪器与试剂ｐＸＳ 2 1 5离子活度计(上海精科雷磁公司 )79 1型磁力加热搅拌器碘离子选择性电极 (江苏电分析仪器厂 )离子强度调节剂 :0 .5ｍｏｌ·Ｌ-1ＫＮＯ3 +0 1ｍｏｌ·Ｌ-1氯乙酸水为二次蒸馏水1 .2　试验方法取 5 0ｍｌ容量瓶若干个 ,分别加入 0 .5ｍｏｌ·Ｌ-1ＫＮＯ3 溶液 5ｍｌ,0 .1ｍｏｌ·Ｌ-1氯乙酸 2…     

具有反Hofmeister行为的新型液膜碘离子选择性电极的研究

具有反Ｈｏｆｍｅｉｓｔｅｒ行为的新型液膜碘离子选择性电极的研究刘冬，陈文灿，袁若，林辉概，俞汝勤（湖南大学化学化工系，长沙４１００８２）离子缔合型液膜阴离子选择性电极的选择性顺序往往与Ｈｏｆｍｅｉｓｔｅｒ亲脂性顺序相一致，即亲脂性强的阴离子优先响应，...     

加碘食盐中微量碘的离子选择性电极测定

在加碘食盐中加入还原剂将KIO3中的IO3^-还原为I^-,使用碘离子选择性电极技术,采用标准曲线法直接测定了溶液中的I-量.并引入表面活性剂作为增敏剂,降低了检测下限,提高了检测的灵敏度.实际测定3种食盐样品,取得了较好的效果.     

流动注射催化动力学光度法测定碘离子

Based on catalysis of I- on the decolor reaction between potassium bromate and indigo carmine in the acid medium,and combined with flow injection analysis,a new flow-injection catalytic kinetic spectrophotometric method was found for determination of iodide in sample.The experimental results show that the determination is carried out at temperature of 80℃ and the concentration of H_2SO_4,KBrO_3,and indigo carmine is 1.2 mol/L,1.8×10~(-2) mol/L and 1.0×10~(-4) mol/L respectively,the linear range for the method is 0.50～1.8 mg/L.The detection limit is 0.0022 mg/L.The relative standard deviation is 1.92%.The proposed method was applied to the determination of iodide in troche successfully.The recovery was between 99.2% and 103.6%.     

离子选择电极流动注射分析同时测定钾和氯

1　引　　言在土壤、饲料、生物组织液分析中 ,钾和氯的测定非常普遍 ,人们常用光度分析、ＩＳＥ电位分析。烟草中的钾和氯含量影响其燃烧性能 ,与焦油量直接相关 ,是烟草成份的必检项目。研究一种快速、自动的分析方法很有意义。作为一种动态测量和检测技术 ,ＦＩＡ已多用于物质含量的检测和过程参数的测量 ,ＩＳＥ ＦＩＡ测定单个离子的含量亦有报道。本实验成功地实现了钾和氯离子的ＩＳＥ ＦＩＡ同时测定 ,方法简单快速。2　原　　理采用两支不同体积的进样管向流路中分别载入ＫＣｌ标准溶液 (Ｃ0 ) ,由于进样体积的差异导致标准溶液具…     

流动注射-微型流通式离子选择性电极测定地热水中高浓度钙(Ⅱ)

采用流动注射-微型流通式钙(Ⅱ)选择电极测定地热水中高浓度钙(Ⅱ)的含量,并对各种影响因素进行了研究。优化的试验条件为:混合盘管长度30cm,载流流量为0.99mL.min-1,采样体积60μL,总离子强度调节缓冲溶液(pH 9.7)由0.02mol.L-1硼砂、0.02mol.L-1氢氧化钠、10mg.L-1钙(Ⅱ)和0.6mol.L-1氯化钠溶液组成,其流量为0.88mL.min-1。方法的线性范围为0.16～20.00g.L-1。对1.00,2.00g.L-1钙标准溶液分别连续测定11次,所得结果的相对标准偏差分别为2.8%,1.8%。方法用于地热水样的分析,加标回收率在102%～111%之间。     

用碘离子选择性电极测定微量联氨

本文提出了用碘离子选择性电极间接测定联氨的方法,其检测下限为5×10~(-5)mol/L。对常见的干扰物质只需进行简单的酸化即可进行测定。     

简易型离子选择电极-流动注射分析仪的研制及卤水中氯、溴和碘的连续测定

本文设计研制了简单实用的流通池,组装了简易型离子选择电极—流动注射分析仪,对体系的分析特点和影响因素进行了考察。此装置性能可靠,能满足简单流注分析的需要,并建立了卤水中Cl~-、Br~-和I~-的连续测定方法。     

Flow injection analysis of potassium using an all-solid-state potassium-selective electrode as a detector

The concentration of potassium was determined by a combination of flow injection analysis (FIA) with an all-solid-state potassium sensor detection. The all-solid-state potassium-selective electrode possessing long-term potential stability was fabricated by coating an electroactive polypyrrole/poly(4-styrenesulfonate) film electrode with a plasticized poly(vinyl chloride) membrane containing valinomycin. The simple FIA system developed in this laboratory demonstrated sensitivity identical to that in the batch system and achieved considerably rapid assay (150 samples h⁻¹). Analyses of soy sauce and control serum samples by this FIA system yielded results in good agreement with those obtained by conventional measurements.     

Flow injection determination of iodide ion in a photographic developing solution using iodide ion-selective electrode detector

A potentiometric flow injection determination method for iodide ion in a photographic developing solution was proposed by utilizing a flow-through type iodide ion-selective electrode detector. The sensing membrane of the electrode was Ag₂S–AgI membrane. The response of the electrode detector as a peak-shape signal was obtained for injected iodide ion in a photographic developing solution. A linear relationship in the subnernstian zone was found to exist between peak height and the concentration of the iodide ion in a photographic developing solution in a concentration range from 0 to 6.0×10⁻⁵ mol l⁻¹. The relative standard deviation for ten injections of 2×10⁻⁵ mol l⁻¹ iodide ion in a photographic developing solution was 0.96% and the sampling rate was approximately 12–13 samples h⁻¹. The iodide ion could be determined under coexisting of an organic reducing reagent and inorganic electrolytes of high concentration in a photographic developing solution sample solution by the present method.     

A selective membrane electrode for iodide ion based on a thiopyrilium ion derivative as a new ionophore

A highly selective electrode for iodide ion based on a thiopyrilium derivative as an excellent ionophore is described. At pH 5.5-8.0, the electrode responds to iodide ion in a linear range from 1.0×10⁻¹ to 8.0×10⁻⁷ M with a slope of 60.2 mV per decade, and a detection limit of 2.0×10⁻⁷ M. Selectivity coefficients determined with the match potential method (MPM) indicate that the interference from inorganic and organic anions is very small. The proposed sensor shows a fast response time of approximately 15 s. It was applied as an indicator electrode in titration of iodide with Ag⁺.     

Determination of phosphate in hydroponic nutrient solutions using flow injection potentiometry and a cobalt-wire phosphate ion-selective electrode

The direct flow injection potentiometric (FIP) analysis of phosphate in hydroponic nutrient solution has been carried out using a cobalt-wire ion-selective electrode (ISE). Synthetic hydroponic nutrient solution, commercial hydroponic nutrient solution and working hydroponic farm nutrient solution were analysed for phosphate using the FIP technique. It is shown that FIP results compare favourably to standard methods of analysis such as spectrophotometry and indirect photometric ion-pair chromatography. Reproducible FIP response curves with a slope of −(47.57±0.03) mV per decade and intercept of −(169.7±0.1) mV were obtained for four separate calibrations in the concentration range 5.0×10⁻⁴–1.0×10⁻² M H₂PO₄⁻. Anion corrections for interferences by Cl⁻, NO₃⁻ and SO₄²⁻ were applied to all samples using the selectivity coefficients determined independently using a fixed interference method. Nevertheless, it was found that anion corrections were not necessary, as the deviations fell within the bounds of experimental error for the cobalt-wire ISE technique (i.e.±2–5% R.S.D.). The proposed FIP method enables the direct determination of phosphate in hydroponic nutrient solutions.     

AAO-CNTs electrode on microfluidic flow injection system for rapid iodide sensing

In this work, carbon nanotubes (CNTs) nanoarrays in anodized aluminum oxide (AAO-CNTs) nanopore is integrated on a microfluidic flow injection system for in-channel electrochemical detection of iodide. The device was fabricated from PDMS (polydimethylsiloxane) microchannel bonded on glass substrates that contains three-electrode electrochemical system, including AAO-CNTs as a working electrode, silver as a reference electrode and platinum as an auxiliary electrode. Aluminum, stainless steel catalyst, silver and platinum layers were sputtered on the glass substrate through shadow masks. Aluminum layer was then anodized by two-step anodization process to form nanopore template. CNTs were then grown in AAO template by thermal chemical vapor deposition. The amperometric detection of iodide was performed in 500-μm-wide and 100-μm-deep microchannels on the microfluidic chip. The influences of flow rate, injection volume and detection potential on the current response were optimized. From experimental results, AAO-CNTs electrode on chip offers higher sensitivity and wider dynamic range than CNTs electrode with no AAO template.     

Preparation and application of a new glucose sensor based on iodide ion selective electrode

An electrode for glucose has been prepared by using an iodide selective electrode with the glucose oxidase enzyme. The iodide selective electrode used was prepared from 10% TDMAI and PVC according our previous study. The enzyme was immobilized on the iodide electrode by holding it at pH 7 phosphate buffer for 10 min at room temperature. The H₂O₂ formed from the reaction of glucose was determined from the decrease of iodide concentration that was present in the reaction cell. The iodide concentration was followed from the change of potential of iodide selective electrode. The potential change was linear in the 4×10⁻⁴ to 4×10⁻³ M glucose concentration (75-650 mg glucose/100ml blood) range. The slope of the linear portion was about 79 mV per decade change in glucose concentration. Glucose contents of some blood samples were determined with the new electrode and consistency was obtained with a colorimetric method. The effects of pH, iodide concentration, the amount of enzyme immobilized and the operating temperature were studied. No interference of ascorbic acid, uric acid, iron(III) and Cu(II) was observed. Since the iodide electrode used was not an AgI-Ag₂S electrode, there was no interference of common ions such as chloride present in biological fluids. The slope of the electrode did not change for about 65 days when used 3 times a day.     

Characterization of home-made silver sulphide based iodide selective electrode

Polycrystalline silver sulphide/silver iodide ion selective electrodes (ISEs) with four different compositions, 9:1, 2:1, 1:1, 1:9 Ag₂S-AgI mole ratios, have been fabricated in the laboratory and characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). X-ray diffraction studies show the presence of Ag₃SI, Ag₂S and AgI crystalline phases in the electrode material. The electrode surfaces have been found to become smoother and lustrous with increasing percentage of silver sulphide in silver iodide. ISE 1:1, ISE 2:1 and ISE 9:1 all responded in Nernstian manner with slopes of about 60 mV/decade change in iodide ion concentration in the linear range of 1 × 10⁻¹ to 1 × 10⁻⁶ M while ISE 1:9 showed sub-Nernstian behavior with slope of about 45 mV up to the concentration 1 × 10⁻⁵ M. Two capacitive loops, one corresponding to the charge transfer process at metal electrode and the back contact and a second loop corresponding to the charge transfer process at membrane-electrolyte interface have been observed at high and low frequency ranges, respectively. Mott-Schottky analysis shows that the materials are n-type semiconductors with donor defect concentrations in the range of 5.1 × 10¹⁴ to 2.4 × 10¹⁹/cm³.     

Electrochemical analysis of -penicillamine using a boron-doped diamond thin film electrode applied to flow injection system

The electroanalysis of -penicillamine in 0.1 phosphate buffer (pH 7) was studied at a boron-doped diamond thin film (BDD) electrode using cyclic voltammetry as a function of concentration of analyte and pH of analyte solution. Comparison experiments were performing using a glassy carbon (GC) electrode. The BDD electrode exhibited a well-resolved and irreversible oxidation voltammogram, but the GC electrode provided only an ill-defined response. The BDD electrode provided a linear dynamic range from 0.5 to 10 mM and a detection limit of 25 μM (S/B≥3) in voltammetric measurement. It was also found that the peak potentials were decreased when the pH of the analyte solution was increased. In addition, penicillamine has been studied by hydrodynamic voltammetry and flow injection analysis with amperometric detection using the BDD electrode. The flow injection analysis results at the diamond electrode indicated a linear dynamic range from 0.5 to 50 μM and a detection limit of 10 nM (S/N≈4). The proposed method was applied to determine -penicillamine in dosage form (capsules), the results obtained in the recovery study (255±2.50 mg per tablet) were comparable to those labeled (250 mg per tablet).     

Citrate selective electrodes for the flow injection analysis of soft drinks, beers and pharmaceutical products

Aiming the establishment of simple and accurate readings of citric acid (CA) in complex samples, citrate (CIT) selective electrodes with tubular configuration and polymeric membranes plus a quaternary ammonium ion exchanger were constructed. Several selective membranes were prepared for this purpose, having distinct mediator solvents (with quite different polarities) and, in some cases, p-tert-octylphenol (TOP) as additive. The latter was used regarding a possible increase in selectivity. The general working characteristics of all prepared electrodes were evaluated in a low dispersion flow injection analysis (FIA) manifold by injecting 500 μl of citrate standard solutions into an ionic strength (IS) adjuster carrier (10⁻² mol l⁻¹) flowing at 3 ml min⁻¹. Good potentiometric response, with an average slope and a repeatability of 61.9 mV per decade and ±0.8%, respectively, resulted from selective membranes comprising additive and bis(2-ethylhexyl)sebacate (bEHS) as mediator solvent. The same membranes conducted as well to the best selectivity characteristics, assessed by the separated solutions method and for several chemical species, such as chloride, nitrate, ascorbate, glucose, fructose and sucrose. Pharmaceutical preparations, soft drinks and beers were analyzed under conditions that enabled simultaneous pH and ionic strength adjustment (pH=3.2; ionic strength=10⁻² mol l⁻¹), and the attained results agreed well with the used reference method (relative error<4%). The above experimental conditions promoted a significant increase in sensitivity of the potentiometric response, with a supra-Nernstian slope of 80.2 mV per decade, and allowed the analysis of about 90 samples per hour, with a relative standard deviation <1.0%.     

Development of a sensitive and selective Riboflavin sensor based on carbon ionic liquid electrode

The electrochemical properties of Riboflavin adsorbed on carbon ionic liquid electrode (CILE) were studied by cyclic voltammetry. A film with a surface coverage of up to 3.3 × 10⁻⁹ mol cm⁻² was formed after 10 min exposure time. Electron transfer coefficient and rate constant of electron transfer across the modified electrode were found to be 0.43 and 3.03 s⁻¹, respectively. Differential pulse voltammetry was used for the determination of Riboflavin. Two linear working ranges of 0.8-110 nM and 0.11-1.0 μM were obtained with correlation coefficients of 0.998 and 0.996, respectively. The experimental detection limit was obtained as 0.1 nM. The relative standard deviation for five replicate analyses was 4.7%. Other soluble vitamins had no significant interferences and the electrode was used for the determination of Riboflavin in pharmaceutical products, nutrition and beverages.