Five-electrode direct current suppressor-detector combiner for ion chromatography: an integration of eluent suppression and resistance detection

An integration of eluent suppressor and resistance detector is proposed based upon the application of a common anode (or cathode), a common ion-exchange membrane, and two independent constant current sources.National Natural Science Foundation of China[20527005

A novel anti-interference and pH-modulation device: application to enzyme-free glucose detection

We report on a novel anti-interference and pH-modulation device (herein after referred to as "device"). It is based on electrodialysis and can continuously increase the pH value of the carrier solution and - at the same time - remove interfering analytical signals obtained for ascorbic acid (AA) and uric acid (UA). The "device" was coupled to the FIA-amperometric detection of glucose. The linear range is from 1 mu mol L(-1) to 0.4 mmol L(-1), with a sensitivity of 213 mu A cm(-2) mM(-1) and a detection limit of 1 mu mol L(-1) at a signal-to-noise ratio of 3. The method was used to sucessfully determine glucose in serum. This study represents a novel technique for overcoming analytical interference and is expected to find applications in liquid chromatography, for example in on-line pH-modulation if different pH values are needed for separation and detection

Development of a novel, sensitive amperometric-FIA glucose biosensor by packing up the amperometric cell with glucose oxidase modified anion exchange resin

In this work, the anion exchange resin (AER) was modified with a layer of glucose oxidase (GOD) and poly(diallyldimethylammonium chloride) (PDDA), respectively, via layer-by-layer electrostatic self-assembling strategy. The PDDA and GOD modified AER (PDDA/GOD/AER) was then packed into a home-made amperometric cell for flow injection analysis (FIA) of glucose. This design simplified the setup by integrating the enzyme reactor into the amperometric cell. And the AER in the cell behaved bifunctional, it was not only the support of enzymes, but also an anti-interference tool due to its retention effect toward ascorbic acid (AA) and uric acid (UA). A platinum modified porous titanium (Pt/PTi) electrode was utilized in the cell as the working electrode (WE), due to its large effective surface area it could increase the response by 8.3 times as compared with the planar pure platinum electrode. The proposed biosensor was very sensitive (22.4 mu A cm(-2) mM(-1)) in glucose quantification, and the linear range was from 1 mu mol L-1 to 2 mmol L-1 with the detection limit of 0.8 mu mol L-1. The biosensor was used for serum glucose determination, and the result obtained was satisfying. This work may have provided a reference design of the amperometric cell which could be adopted in other enzymatic-FIA biosensors. (C) 2009 Elsevier B.V. All rights reserve

A four-electrode microconstant direct current resistance detector for ion chromatography applying ion-exchange membrane and porous electrode

A four-electrode microconstant direct current resistance detector for ion chromatography not sensitive to the effects of electrode polarization, capacitance, and electrolysis by-products is proposed. A constant current of microampere magnitude is applied across the current electrodes of the four-electrode device, and the voltage responses between the detection probes are directly picked up by a high input impedance instrumentation amplifier. The ion-exchange membranes, which separate the detection chamber from the electrolysis chambers, enable the measurement of solution resistance free of the interference of electrolysis by-products. Two resin beds in the detection chamber serve as ion conductors while reduce the dead volume of the detector. Recycled detection effluent supplies water for the electrolysis reactions at the current electrodes to sustain constant current in solution. The porous detection probes provide microchannel for the flowing solution while indicating signals. Owing to the constant current excitation, the electronics setup becomes simple. The cell configuration, operating principle, electronics, and error analysis of this detection mode are discussed along with their use for suppressed anion chromatography. Experimental data show that this four-electrode direct current detection mode is comparable to conventional two-electrode alternating current method. (C) 2010 Elsevier B.V. All rights reserved.National Natural Science Foundation of China [20527005

Determination of steroid sex hormones in wastewater by stir bar sorptive extraction based on poly(vinylpyridine-ethylene dimethacrylate) monolithic material and liquid chromatographic analysis

In this study, a simple and rapid method was developed for the determination of seven steroid hormones in wastewater. Sample preparation and analysis were performed by stir bar sorptive extraction (SBSE) based on poly(vinylpyridine-ethylene dimethacrylate) monolithic material (SBSEM) combined with high-performance liquid chromatography with diode array detection. To achieve the optimum extraction performance, several main parameters, including extraction and desorption time, pH value and contents of inorganic salt in the sample matrix, were investigated. Under the optimized experimental conditions, the method showed good linearity and repeatability, as well as advantages such as sensitivity, simplicity, low cost and high feasibility. The extraction performance of SBSEM to the target compounds also compared with commercial SBSE which used polydimethylsiloxane as coating. Finally, the proposed method was successfully applied to the determination of the target compounds in wastewater samples. The recoveries of spiked target compounds in real samples ranged from 48.2% to 110%. (C) 2008 Elsevier B.V. All rights reserved

Electrochemical Determination of Trace Amouns of Gold(Ⅲ)by Cathodic Sptripping Voltammetry Using a Carborn Paste Electroele Modified with Bacteria

研究用细菌修饰的碳糊电极对金离子的响应特性，并应用该电极检测水溶液中的金离子，金离子浓度在１０～１００μｇ／ｍＬ．呈线性关系，重现性为３．４％，检测限达１ｎｇ／ｍＬ．电极具有制备简单，灵敏度高等优点．文中还讨论了金离子在还原菌修饰的碳糊电极上的还原机理．An electrochemically pretreated carbon paste electrode modified with bacteria has been studied and used for determination of trace amounts of gold(Ⅲ). A detection limit of 1 ng/mL was obtained by applying cathodic stripping valtammetry. There is a linear relationship between the concentration and peak height in the range of 10～100 μg/mL. The ralative standard deviation of the response to 84.7 μg/mL Au(Ⅲ) is 3.43%.作者联系地址：厦门大学化学系固体表面物理化学国家重点实验室国家教委材料和生命过程分析科学开放研究实验室Author's Address: State Key Lab. for Phys. Chem. of Solid Surf., Depet. of Chem., Xiamen Univ., Xiamen 36100

Preparation and Application of Gold_Film on the Surface of Bacterial_Modified Carbon Paste Electrode

本文提出一种采用电化学方法在巨大芽孢杆菌Ｄ０１修饰的碳糊电极表面制备超细微粒金膜的新方法，获得由平均粒径为８０ｎｍ金微粒组成的金膜．该方法操作简单，耗金量少，以此金膜作为工作电极检测水溶液中痕量铜具有良好的重现性和线性，检测灵敏度达０．０２ｎｇ／ｍＬ．该电极既可象金片电极多次反复被使用，也可以象碳糊电极一样不断更新表面A novel method for preparation of gold_film composed of ultra_fine gold particles was reported in this paper. The gold_film was prepared by electrochemical method on the surface of the paste electrode modified with the strain Bacillus sp. D01 which has strong ability to absorb and reduce Au3+. In addition, this paper reported an experimental method of determining trace amount of Cu2+ in water solution using cathodic stripping analysis to estimate the performances of the obtained gold_film. The experimental results indicated that this new method for preparation of gold_film is simple. The obtained gold_film electrode is stable and sensitive to determining Cu2+.作者联系地址：厦门大学化学系，固体表面物理化学国家重点实验室，国家教委材料和生命过程分析开放研究实验室Author's Address: Dept. of Chem., State Key Lab. for Phys. Chem. of Solid Surf., Res. Labo. of SEDC of Anal. Sci. for Materials and Life Chem., Xiamen Univ., Xiamen 36100

Electrochemical Study of the Corrosion Behavior of Coalesced Copper and SW-206 Stainless Steel in the Acetic-Acid Solution

应用交流阻抗和极化曲线法研究磷脱氧铜和ＳＷ－２０６不锈钢在醋酸介质中腐蚀行为及过程的控制特征，比较介质温度、浓度及溶解氧对这两种金属在醋酸中腐蚀行为的影响，分析其原因所在，为石油化工中的醋酸设备的正确选材及有效防腐提供理论和实验依据．In order to provide a theoretic and experimental consideration for the material selection and anit-corrosion in the petrochemical industries the corrosion behavior of coalesced copper and sw-206 stainless steel in the acetic acid solution was studied by electrochemical impedance spectroscopy and polarization techniques. The effects of the temperature,acetic acid concentration and solubilized oxygen in the acetic acid solution on the corrosion process of this two metals were analyzed. It was found that these effects obviously accelerate corrosion process for the coalesced copper,but no apparent influnce for the sw-206 stainless steel.In the the acetic acid solution,containing water and oxygen were beneficial for stabilizing the passivation state of sw-206 stainless steel,and however were detrimental for the corrosion resistance of coalesced copper.作者联系地址：厦门大学化学系，上海石化股份公司机械研究所Author's Address: Department of Chemistry Xiamen University,Xiamen 361005Sun Zhanmei;Wu Xueqin;Wang BiaoMechanics Institute,Shanghai Petrochemistry Corporation,Shanghai 20054

Association of Tirofiban With Functional Outcomes After Thrombectomy in Acute Ischemic Stroke Due to Intracranial Atherosclerotic Disease.

BACKGROUND AND OBJECTIVE: To investigate the efficacy and safety of IV infusion of tirofiban before endovascular thrombectomy for patients with large vessel occlusion due to intracranial atherosclerotic disease. The secondary objective was to identify potential mediators for the clinical effect of tirofiban. METHODS: Post hoc exploratory analysis of the Endovascular Treatment With versus Without Tirofiban for Patients with Large Vessel Occlusion Stroke (RESCUE BT) trial, which was a randomized, double-blinded, placebo-controlled trial at 55 centers in China from October 2018 to October 2021. Patients with occlusion of the internal carotid artery or middle cerebral artery due to intracranial atherosclerosis were included. The primary efficacy outcome was the proportion of patients achieving functional independence (defined as modified Rankin scale 0-2) at 90 days. Binary logistic regression and causal mediation analyses were used to estimate the treatment effect of tirofiban and the potential mediators. RESULTS: This study included 435 patients, of whom 71.5% were men. The median age was 65 (interquartile range [IQR] 56-72) years, with a median NIH Stroke Scale of 14 (IQR 10-19). Patients in the tirofiban group had higher rates of functional independence at 90 days than patients in the placebo group (adjusted odds ratio 1.68; 95% CI 1.11-2.56, p = 0.02) without an increased risk of mortality or symptomatic intracranial hemorrhage. Tirofiban was associated with fewer thrombectomy passes (median [IQR] 1 [1-2] vs 1 [1-2], p = 0.004), which was an independent predictor of functional independence. Mediation analysis showed tirofiban-reduced thrombectomy passes explained 20.0% (95% CI 4.1%-76.0%) of the effect of tirofiban on functional independence. DISCUSSION: In this post hoc analysis of the RESCUE BT trial, tirofiban was an effective and well-tolerated adjuvant medication of endovascular thrombectomy for patients with large vessel occlusion due to intracranial atherosclerosis. These findings need to be confirmed in future trials. TRIAL REGISTRATION INFORMATION: The RESCUE BT trial was registered on the Chinese Clinical Trial Registry: chictr.org.cn, ChiCTR-INR-17014167. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that tirofiban plus endovascular therapy improves 90-day outcome for patients with large vessel occlusion due to intracranial atherosclerosis