阻抑茜素红S褪色动力学光度法测定痕量汞

在HAc—NaAc介质中,以邻菲啰啉作活化剂,痕量Cr（Ⅵ）对H2O2氧化茜素红S褪色反应存在强烈的催化作用,而Hg（Ⅱ）对此褪色反应具有明显的阻抑作用,由此建立了测定痕量Hg（Ⅱ）的新阻抑动力学光度法。该方法线性范围为0～1．6μg／mL,检出限为2．6×10^-8g／mL,应用于污水中Hg（Ⅱ）的测定,结果满意。     

A New Turbidimetric Method for Determination of Melamine Based on its Reaction with Mercury(II)

A turbidimetric technique based on a reaction between Hg(II) and melamine is described for the measurement of melamine content of wastewater of a petrochemical company. The present technique is rapid and simple, uses a small amount of reagent and is set up with low‐cost equipment, making this system economically viable. The experimental conditions such as volume of reagent, pH of buffer, stirring time, stirring speed, ionic strength, etc. were optimized and used in plotting the calibration curve. The linear dynamic range was 1–70 mg/L with a limit of detection of 0.3 mg/L. Repeatability of the proposed method is good, and the relative standard deviation (RSD%) is less than 1.5%. Interferences studies showed that the common compounds existing in wastewater have no negative effect on the efficiency of the method at relatively high concentrations. Finally, the proposed method has been successfully used in determination of melamine in wastewater of Urmia Petrochemical Company.     

Spectrometric Determination of Ti(IV) With an Azopyrazolonic Derivative

Abstract

Spectrometric studies on the complexation of Ti(IV) with a new organic reagent obtained by coupling 3-methyl-1-phenyl-5-pyrazolone with diazotized 3-amino-4-hydroxy-benzene-sulphonic acid were carried out.

A 1:2 Ti(IV):reagent complex, which is soluble in water, is formed at pH 5–6.2. The maximum absorbance of the complex lies at λ =520nm, where the absorbance of the reagent is very low. The molar absorptivity at this wavelength is 5 × 10³ L mol^?1 cm^?1; the value of log K is 8.0 ± 0.2. at 20 ± 1°C and pH=5.6.     

有机锗(Ge-132)中微量无机锗Ge(IV)的测定──苯芴酮分光光度法

在9mol／L盐酸介质中，用四氯化碳萃取，使无机锗Ge（IV）与其主体有机锗及其它杂质元素分离，用水反萃取，于1～1．5mol／L盐酸溶液中，在十六烷基三甲基漠化铵存在下，苯芴酮与Ge（IV）形成橙红色不溶性络合物，于波长510nm处测定其吸光度，获得了满意的效果。     

Ultrasensitive Silicon Nanoparticle Ratiometric Fluorescence Determination of Mercury(II)

A novel ratiometric fluorescence sensing system for the ultrasensitive detection of Hg²⁺ was developed. It used aminofunctionalized silicon nanoparticles and rhodamine B, which exhibit two distinct fluorescence emission peaks at 449 and 581?nm, respectively, under a single excitation wavelength (350?nm). The fluorescence of the amino-functionalized silicon nanoparticles was selectively quenched by Hg²⁺, while that of rhodamine B was insensitive to Hg²⁺. The ratio of fluorescence intensities at 449–581?nm linearly decreased with increasing concentrations of Hg²⁺ from 0.005–0.1 and 0.1–7?µM within 0.5?min, and a detection limit as low as 3.3?nM was achieved. Moreover, the ratiometric fluorescence sensing system exhibited good selectivity toward Hg²⁺ over other metal ions with relatively low background interference, even in a complex matrix such as lake water. Most importantly, the practical use of this sensing system for Hg²⁺ detection in real water samples was also demonstrated.     

阻抑动力学光度法测定痕量邻苯二酚

在pH8．0的KH2PO4-Na2HPO4缓冲介质中，Mn(Ⅱ)催化高碘酸钾氧化二甲酚橙的褪色反应，邻苯二酚可灵敏地阻抑。研究了该指示反应的动力学参数及阻抑反应的机理，建立了动力学光度法测定痕量邻苯二酚的新方法。方法检出限为12．3ng／mL，线性范围在0．5～5．0μg／25mL和6．0～11．0μg／25mL。采用分馏法用于污水中邻苯二酚的测定，结果满意。     

基于抑制作用的新型葡萄糖氧化酶传感器测定环境污染物汞离子的研究

本文提出了一种基于抑制作用的新型葡萄糖氧化酶生物传感器用于测定环境样品中二价汞离子。其工作原理是汞离子对电极上葡萄糖氧化酶分子的抑制作用引起响应电流的下降而产生一可测定信号。详细探讨了电极的氧化还原反应机理及测试性能。该传感器对汞离子的检出限是0．49ng／mL,抑制率和汞离子浓度的自然对数值在0．49～783．21ng／mL和783．21ng／mL-25．55μg／mL范围内分别呈良好的线性关系。酶电极在抑制后可以完全恢复活性。考察了铅(Ⅱ)、铜(Ⅱ)、镉(Ⅱ)和铬(Ⅲ)离子对汞离子测定的干扰。测定了汞离子在土壤浸出液中的回收率,结果良好。     

Spectrometric Studies on the Complexation of Pd(II), Fe(III) and Pt(IV) with mandelazo I

Abstract

A spectrometric study of the reaction between Pd(II), Fe(III) and Pt(IV) ions, and Mandelazo I was carried out. The optimum conditions favouring the formation of the complexes are extensively investigated. The stoichiometry of the complexes formed in solution (1:2, 1:1, 1:1), their apparent stability constants (5.45 × 10⁹, 2.39 × 10⁶, 4.12 × 10⁵) and the ranges for obedience to beer's law (0.2 – 6.4, 0.25 – 7.0, 1.5 – 42.0 μg/mL) are reported for Pd(II), Fe(III) and Pt(IV), respectively. The effect of some metal ions including Cu(II), Zn(II), Mn(II), Cd(II), Hg(II), Co(II), Ni(II), Be(II), Al(III), Th(IV) and U(VI), on the maximum absorbance of the formed complexes was also investigated.     

氢化物发生-原子荧光光谱法测定水中汞的测量不确定度分析

对氢化物发生-原子荧光光谱法测定水中汞的分析方法的测量不确定度进行了估计。认为在分析的全过程中,标准溶液的配制、校准曲线的绘制以及试样的分析是测量不确定度的三项主要来源。基于这一认识,建立了相应的数学模型,对关系式中的各个变量作了分析并对其不确定度进行量化。最后,按统计学的计算方法给出了合成不确定度和扩展不确定度。     

Polyviologen Modified Glassy Carbon Electrode Employed for Anodic Stripping Voltammetric Determination of Mercury(II)

In this study, a polyviologen modified glassy carbon electrode (PVGCE) was used to detect Hg(II) in aqueous solutions containing significant amounts of chloride anions in order to demonstrate the electroanalytical application of the electropolymerized polyviologen. The polyviologen thin film was formed on the electrode surface by applying a constant potential of ?1.0 V in the pH 4.2 Britton–Robinson (BR) buffer solution that contains 0.1 wt% of viologen oligomers. The PVGCE was found capability to improve the detection limit of Hg(II) in the solutions with high concentration of chloride because Hg(II) forms negative complex ions HgCl that can be accumulated to PVGCE by the anion‐exchange characteristic of polyviologen. With 5 minutes accumulation at ?0.2 V, the adsorbed HgCl anions were reduced to Hg and deposited on the electrode surface, and were determined with the following anodic stripping differential pulse voltammetry (ASDPV). The dependence of anodic stripping current versus concentration was linear from 1 ppb (5 nM) to 100 ppb (0.5 μM) with a regression coefficient of 0.9959.     

氢化物发生-原子荧光光谱法测定中药材中汞和砷

用氢化物发生-原子荧光光谱法测定了产于海南省的5种中药材,即槟榔、益智、砂仁、巴戟天及沉香中汞含量及砷含量.对试样的预处理和消解方法以及仪器的工作条件作了详述,还对各种对测定有影响的因素,包括试样消解所用的酸的种类及其浓度,硼氢化钾的加入浓度,五价砷的预还原和共存金属离子的干扰等也作了研究并予以优化选择.方法的检出限分别为1.5 ng·g-1(汞)和7.0 ng·g-1(砷).在对5种药材的实样进行分析的基础上作了回收率试验,所得结果为90%～93%(汞)和90%～91%(砷).     

二甲酚橙-KBrO_3体系阻抑反应动力学光度法测定蛋白质

在稀硫酸介质中,蛋白质可灵敏地阻抑溴酸钾氧化二甲酚橙褪色的兰多尔特(Landolt)反应,据此建立了阻抑动力学光度法测定痕量蛋白质的新方法.在优化实验条件下,于430 nm波长处进行测定,蛋白质含量在0.2～2.0 mg/L范围内与吸光度呈线性关系,检出限为0.141 mg/L,标准加入回收结果满意.     

Polythymine Oligonucleotide‐Modified Gold Electrode for Voltammetric Determination of Mercury(II) in Aqueous Solution

Polythymine oligonucleotide (PTO)‐modified gold electrode (PTO/Au) was developed for selective and sensitive Hg²⁺ detection in aqueous solutions. This modified electrode was prepared by self‐assembly of thiolated polythymine oligonucleotide (5′‐SH‐T₁₅‐3′) on the gold electrode via Au? S bonds, and then the surface was passivated with 1‐mercaptohexanol solution. The proposed electrode utilizes the specific binding interactions between Hg²⁺ and thymine to selectively capture Hg²⁺, thereby reducing the interference from coexistent ions. After exchanging the medium, electrochemical reduction at ?0.2 V for 60 s, voltammetric determination was performed by differential pulse voltammetry using 10 mM HEPES; pH 7.2, 1 M NaClO₄ as supporting electrolyte. This electrode showed increasing voltammetric response in the range of 0.21 nM Hg²⁺, with a relative standard deviation of 5.32% and a practical detection limit of 60 pM. Compared with the conventional stripping approach, the modified electrode exhibits good sensitivity and selectivity, and is expected to be a new type of green electrode.     

Determination of Traces of Mercury (II) and Phenylmercury by Direct Polyurethane foam Thin-Layer Spectrophotometry

Abstract

The determination of mercury and phenylmercury in the ppb concentration range using polyurethane foam (PUF) thin-layer spectrophotometry has been described. Sorption of mercury and phenylmercury into foam parallepiped loaded with diphenylthiocarbazone (dithizone) contributed to considerable improvement in the absorbance value of the colored species, being concentrated about 140 times.

The method allowed the achievement of satisfactory results, the detection limits are 5 and 10 μg per litre for mercury and phenylmercury, respectively, for 100ml sample volume. The average recovery from tap water amounts to 100% for mercury and 96.6% for phenylmercury.     

Novel Screen-Printed Gold Nano Film Electrode for Trace Mercury(II) Determination Using Anodic Stripping Voltammetry

Integrating the screen printing technique with the vacuum evaporation method, we developed a novel and disposable screen-printed gold film electrode (SPGFE) in the present work. First, a conductive silver layer, a connection graphite-carbon layer, and an insulating polymer layer were successively printed onto a flexible polyethylene terephthalate (PET) substrate. Then, a gold thin film was achieved on the scheduled vacant site by use of the vacuum evaporation method. In order to enhance the electroanalytical performance of the SPGFE, the thickness of the gold film was controlled in the range of 70–80 nm under optimum conditions. The fabricated SPGFE was applied to detect trace mercury(II) based on the square-wave anodic stripping voltammetry (SWASV). The results indicated that the proposed SPGFE exhibited higher sensitivity to trace mercury(II) than the gold disc electrode. The stripping current was linearly related to the concentration of mercury(II) in the range of 16–280 µg/L (R² = 0.9919) and 1.2–8.0 µg/L (R² = 0.9977), with a detection limit of 0.8 µg/L (S/N = 3) under 180 s accumulation. The SPGFE was further used to detect mercury in real samples, and the obtained results revealed a good agreement with those of inductively coupled plasma atomic emission spectrometry (ICP-AES) and atomic absorption spectroscopy (AAS). The highly sensitive and environmental friendly electrode, as another type of “mercury-free” electrode, holds great promise in stripping measurements.     

氢化物发生-原子荧光光谱法同时测定中药材中砷和汞

采用氢化物发生-原子荧光光谱法同时测定了产于吉林省长白山的中药材杜仲中砷和汞的含量,建立了同时测定砷汞含量的分析方法。讨论了各种对测定有影响的因素,并优化了分析条件。方法的检出限分别为2.9×10-4μg/mL(砷),0.013ng/mL(汞)。该方法简便、快速且灵敏度高,样品测定结果满意。     

A Novel Ion‐Selective Electrode for Determination of the Mercury(II) Ion Based on Schiff Base as a Carrier

A new poly(vinyl chloride) (PVC) membrane ion‐selective electrode based on bis‐salicyladehyde‐diaminjodipropylamine (BSDDA) as an ion carrier was successfully applied to the detection of Hg²⁺ ions. This electrode displayed good selectivity toward Hg²⁺ in comparison with other metal ions and exhibited a Nernstian slope of 30.5 ± 0.4 mV per decade of Hg²⁺ over a concentration range of 9.5 × 10^?7 to 6.4 × 10^?2 M of Hg²⁺ in the pH range 1.5 to 3.5. The detection limit was 7.0 ± 0.2 × 10^?7 M and response time was about 10 s to 25 s. The electrode can be used at least 2 months without apparent divergence in potential. In addition, the effects of experimental parameters such as membrane composition, nature and amounts of plasticizer and additive were investigated. The proposed electrode could be used as an indicator electrode in the detection of Hg²⁺ in samples.     

Zero-Crossing Derivative Spectrophotometric Determination of Mercury(II) And Palladium(II) with 5-(3,4-Methoxyhydroxyphenylmethylene)-2-thioxo-1-3-thiazolidine and Cetyltrimethylammonium Bromide

Abstract

A method is proposed for the simultaneous determination of mercury(II) and palladium(II) by first-derivative spectrophotometry based on the absorption spectra of their complexes with 5-(3,4-Methoxyhydroxyphenylmethylene)-2-thioxo-1,3-thiazolidine [5-(3,4-methoxyhydroxybenzylidene) rhodanine]. Zero-crossing measurement technique is found suitable for the measurement of the first-derivative value at the specified wavelengths. Mercury(II) (0.4-1.4 μg ml^?1) and palladium(II) (0.08 - 1.8 μg ml^?1) in different ratios have been determined simultaneously. A critical evaluation of the proposed method is performed by statistical analysis of the experimental data.     

Structural Investigations and Thermal Behaviour of Mercury(II) Sulfito Complexes

The crystal structures of (NH₄)[HgSO₃Cl] ( 1 ) and of (NH₄)₂[Hg(SO₃)₂] ( 2 ) were determined from single crystal diffractometer data sets. 1 : 22 °C, Pnma, Z = 4, a = 15.430(3), b = 5.525(1), c = 6.679(1) Å, R(F) = 0.0256, R_w(F²) = 0.0642 (all 1056 unique reflections). 2 : ?108 °C, P2₁2₁2₁, Z = 4, a = 6.2240(4), b = 9.3908(6), c = 13.6110(8) Å, R(F) = 0.0179, R_w(F²) = 0.0493 (all 2699 unique reflections). The structure of 1 contains bent Cl‐Hg‐SO₃ entities (site symmetry m; d(Hg‐Cl) = 2.3403(13) Å, d(Hg‐S) = 2.3636(12) Å, ∠(Cl‐Hg‐S) = 164.51(5)°, d(S‐O) 2×1.458(3) Å, 1.468(4) Å, = 1.461Å) linked to undulated ribbons parallel to the b ‐axis by intermolecular secondary bonds SO···Hg (d(O···Hg) = 2×2.595(3) Å). These ribbons in turn aggregate to layers around the bc ‐plane. The layers are stacked along the a ‐axis with interlayer distances of a /2. The structure of 2 is made up of O₃S‐Hg‐SO₃ moieties (d(Hg‐S) = 2.3935(7), 2.3935(8) Å; ∠(Hg‐S‐Hg) = 174.41(3)°; = 1.474Å), that are linked to ribbons parallel to the a axis by coordination of Hg to three remote O atoms (2.801(4) < d(Hg‐O) < 2.844(3) Å). Adjacent ribbons are joined together by an additional Hg‐O contact of 2.733(3) Å, leading to a three‐dimensional anionic framework. Both crystal structures are stabilised by disordered NH₄⁺ cations, placed between the anionic layers or in the vacancies of the framework, via moderate hydrogen bonding interactions N‐H···O with donor‐acceptor distances ranging from 2.8 to 3.2Å. 1 and 2 were further characterised by thermal analysis (TG, DSC). They start to decompose at temperatures above 130 °C.