Catalytic spectrophotometric determination of molybdenum (VI) with the hydrazine-metanil yellow system

A new catalytic Spectrophotometric method for the determination of trace amounts of molybdenum (VI) has been proposed. The method is based on the catalytic effect of Mo(VI) on the reduction of metanil yellow by hydrazine dihydrochloride. Under experiment condition, the linear range of determination is 20–160 ng/mL for molybdenum and the detection limit is 11.2ng/mL. The method has been used to determine trace molybdenum in bean samples with the recovery of 96.0–99.0%, with relative standard deviations of 1.50–2.53%.     

Ultra trace analysis of molybdenum by differential pulse polarography and adsorptive stripping voltammetry in the presence of 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone

Summary Different polarographic and voltammetric techniques for the determination of molybdenum at the trace level have been investigated. As a result, a new high-sensitivity procedure for the determination of molybdenum by adsorptive stripping voltammetry was developed. The method is based on the reaction of molybdenum(VI) with 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (chloranilic acid) to produce a complex which is absorbed onto mercury at –0.20 V (vs. Ag/AgCl, 3 mol/l KCl) from pH 2.7 solution. The cathodic stripping peak at –0.62 V can be used to determine molybdenum with a detection limit of 0.02 ng/ml after 5 min deposition time. The relative standard deviation for the determination of 0.1 ng/ml Mo after 5 min stirred collection was 6.6%. Interference from various inorganic ions and organic substances are reported. The method was applied to the determination of molybdenum traces in waters; interfering organic substances in polluted waters were destroyed by oxidative digestion in a microwave oven.     

A rapid spectrophotometric method for the determination of molybdenum in industrial, environmental, biological and soil samples using 5,7-dibromo-8-hydroxyquinoline.

A very simple, ultra-sensitive and highly selective non-extractive spectrophotometric method for the determination of trace amount of molybdenum(VI) using 5,7-dibromo-8-hydroxyquinoline (DBHQ) has been developed. 5,7-Dibromo-8-hydroxyquinoline reacts in a slightly acidic solution (0.05 - 1.0 M H2SO4) with molybdenum(VI) to give a deep greenish-yellow chelate which has an absorption maximum at 401 nm. The reaction is instantaneous and the absorbance remains stable for over 24 h. The average molar absorption coefficient and Sandell's sensitivity were found to be 4.13 x 10(3) L mol(-1) cm(-1) and 7 ng cm(-2) of molybdenum(VI), respectively. Linear calibration graphs were obtained for 0.1 - 50 microg mL(-1) of molybdenum(VI). The stoichiometric composition of the chelate is 1:3 (Mo:DBHQ). A large excess of over 50 cations, anions and some common complexing agents (e.g. EDTA, oxalate, citrate, phosphate, thiourea, SCN-) do not interfere with the determination. The method was successfully used in the determination of molybdenum in several Standard Reference Materials (alloys, steels and waters) as well as in some environmental waters (inland and surface), biological samples (human blood and urine), soil samples, solution containing both molybdenum(V) and molybdenum(VI) and complex synthetic mixtures. The method has high precision and accuracy (S = +/-0.01 for 0.5 microg mL(-1)).     

氯酸钾体系催化动力学光度法测定痕量钒(Ⅱ)

研究了在0.1 mol/L H3PO4介质中,活化剂抗坏血酸的作用下,V(Ⅴ)催化KClO3氧化甲基红褪色的指示反应,由此建立了一种测定痕量V(Ⅱ)的催化动力学光度新方法。研究了影响该催化褪色反应的因素。方法的线性范围为0.09～7.0 ng/mL,检出限为2.9×10-2 ng/mL。方法用于实际样品的测定。     

溴酸钾-二甲酚橙体系-顺序注射-催化光度法测定痕量钒

在酸性介质条件下,钒(Ⅳ)能显著催化溴酸钾对二甲酚橙的氧化褪色反应。据此建立了测定痕量钒(Ⅳ)的顺序注射催化光度法。方法的线性范围为0.5~50ng/mL、检出限为0.4ng/mL。对10ng/mL的钒(Ⅳ)连续11次测定的相对标准偏差为1.1%。用于环境水样中痕量钒(Ⅳ)的测定,加标回收率为91%~108%。     

Column preconcentration and electrothermal atomic absorption spectrometric determination of rhodium in some food and standard samples

In the present work, an electrothermal atomic absorption spectrometric method has been developed for the determination of ultra‐trace amounts of rhodium after adsorption of its 2‐(5‐bromo‐2‐pyridylazo)‐5‐diethylaminophenol/tetraphenylborate ion associated complex at the surface of alumina. Several factors affecting the extraction efficiency such as the pH, type of eluent, sample and eluent flow rates, sorption capacity of alumina and sample volume were investigated and optimized. The relative standard deviation for eight measurements of 0.1 ng/mL of rhodium was ±6.3%. In this method, the detection limit was 0.003 ng/mL in the original solution. The sorption capacity of alumina and the linear range for Rh(III) were evaluated as 0.8 mg/g and 0.015–0.45 ng/mL in the original solution, respectively. The proposed method was successfully applied for the extraction and determination of rhodium content in some food and standard samples with high recovery values.     

催化光度法测定痕量钼──钼(Ⅵ)－盐酸联氨－橙黄Ⅳ催化光度新体系

基于盐酸介质中,钼(Ⅵ)催化盐酸联氨还原橙黄Ⅳ的反应,建立了动力学分光光度法测定痕量钼的新方法。本法检出限为3.7×10^-3μg/mL,测定钼量范围为0.025～1.8μg/mL;已将此法用于测定绿豆中的钼及钼酸铅和钼酸钡的溶度积。     

Application of multiwalled carbon nanotubes as solid phase extraction sorbent for preconcentration of trace copper in water samples

The adsorption behavior of multiwalled carbon nanotubes (MWNTs) toward copper has been investigated systemically, and a new method has been developed for the determination of trace copper in water samples based on preconcentration with a microcolumn packed with MWNTs prior to its determination by flame atomic absorption spectrometry. The optimum experimental parameters for preconcentration of copper, such as pH of the sample, sample flow rate and volume, elution solution and interfering ions, have been investigated. Copper can be quantitatively retained by MWNTs in the pH range 5-8, and then eluted completely with 0.5 M HNO3. The detection limit of this method for Cu was 0.42 ng/mL, and the RSD was 3.5% at the 10 ng/mL Cu level. The method was validated using a certified reference material, and has been successfully applied for the determination of trace copper in water samples.     

ICP-MS法测定磁致冷材料-钆硅锗系合金中Mo、 Mn、 Al、 V、 Ni、 Cu、 Ga、 Fe

建立了ICP-MS法测定磁致冷材料-钆硅锗系合金中Mo、 Mn、 Al、 V、 Ni、 Cu、 Ga、 Fe八种痕量杂质元素的方法, 并对ICP-MS工作参数及条件进行了优化. 方法的检出限为0.1～0.6 ng/mL, 测定下限为0.5～3 ng/mL, 回收率在95.5%～109%, 相对标准偏差(n=11)为1.3%～7.6%. 采用该方法对磁致冷材料-钆硅锗系合金实际样品进行了分析, 结果表明精密度和准确度均满足痕量分析的要求.     

Simultaneous voltammetric determination of Mo(VI) and W(VI) by adsorptive differential pulse stripping method using adaptive neuro-fuzzy inference system

An adsorptive differential pulse stripping method is proposed for the simultaneous determination of molybdenum and tungsten based on the formation of their complexes with a novel proton transfer compound, [phenH]⁺[pyzdc]^?, containing both pyrazine-2,3-dicarboxylic acid and 1,10-phenanthroline. The optimum experimental conditions were obtained using 0.052 mM [phenH]⁺[pyzdc]^? ligand, pH 3.3, accumulation potential of ?0.1 V versus Ag/AgCl, accumulation time of 60 s and scan rate of 33.3 mV/s. An adaptive neuro-fuzzy inference system (ANFIS) was utilized for the analysis of the voltammogram data. The detection limits were 4.0 ng/mL for Mo(VI) and 3.0 ng/mL for W(VI). The influence of potential interfering ions on the determination of molybdenum and tungsten was studied. The procedure was applied to the simultaneous determination of molybdenum and tungsten in some water samples.     

反相高效液相色谱同时测定铼与钼的方法研究

以二乙基二硫代氨基甲酸钠（NaDDTC）为柱前衍生试剂,采用高效液相色谱法（HPLC）建立了钼与铼2种金属离子最佳分离条件及定性定量分析方法．结果表明：在C18色谱柱上,以甲醇-水（15：85V/V,含有10mmol／LpH5乙酸-乙酸钠缓冲溶液）作为流动相,能有效的分离2种金属离子,检出限分别为2．1ng／mL和1．3ng／mL,线性范围和线性关系满足定量分析的要求．     

荧光动力学法测定唾液中痕量硫氰根

人体内的SCN-主要分布于人体体液及代谢物中,如唾液、血浆、尿液等。其来源主要有两种途径:一是烟草中氰化物的代谢产物,人体内硫氰酸盐的含量是区别吸烟者和不吸烟者的重要标志[1,2];二是某些食物的代谢产物,如卷心菜等。硫氰酸盐可作为药物用于治疗甲状腺疾病,但体液中SCN-含     

Dispersive liquid-liquid microextraction of Fe(II) and Cu(II) with diethyldithiocarbamate and their simultaneous spectrophotometric determination using mean centering of ratio spectra

A new dispersive liquid-liquid microextraction (DLLME) method for preconcentration of trace quantities of Fe(II) and Cu(II) followed by their spectrophotometric determination has been developed. For the extraction, an appropriate mixture of ethanol (the disperser solvent) and carbon tetrachloride (the extraction solvent) was injected rapidly into the water sample containing Fe(II) and Cu(II) after formation of complexes with diethyldithiocarbamate. Mean centering (MC) of ratio spectra has been used for simultaneous determination of Fe(II) and Cu(II). Linear range of the method is 1.0–100 ng/mL for Fe(II) and 0.3–100 ng/mL for Cu(II), the detection limit is 0.53 ng/mL and 0.14 ng/mL Cu(II), resp. The interference effect of some anions and cations is reported. The method was applied to the determination of Fe(II) and Cu(II) in well water samples.     

铜(Ⅱ)催化PHA的褪色反应特性及应用

本文研究了铜(Ⅱ)催化抗坏血酸还原多卤代变色酸双偶氮胂类试剂(PHA)的褪色反应特性, 讨论了试剂结构对褪色反应动力学特性的影响, 探讨了反应机机。以三氯偶氮胂为代表, 拟定了测定痕量铜(Ⅱ)的新方法, 其检出限为3.06×10^-^1^2g/mL, 线性范围为0~28ng/10mL。用于生物材料中痕量铜(Ⅱ)的测定, 结果满意。     

Determination of trace molybdenum in biological and water samples by graphite furnace atomic absorption spectrometry after separation and preconcentration on immobilized titanium dioxide nanoparticles

A new method has been developed for the determination of trace molybdenum based on separation and preconcentration with TiO₂ nanoparticles immobilized on silica gel (immobilized TiO₂ nanoparticles) prior to its determination by graphite furnace atomic absorption spectrometry (GFAAS). The optimum experimental parameters for preconcentration of molybdenum, such as pH of the sample, sample flow rate and volume, eluent and interfering ions, have been investigated. Molybdenum can be quantitatively retained by immobilized TiO₂ nanoparticles at pH 1.0 and separated from the metal cations in the solution, then eluted completely with 0.5 mol L^?1 NaOH. The detection limit of this method for Mo was 0.6 ng L^?1 with an enrichment factor of 100, and the relative standard deviation (RSD) was 3.4% at the 10 ng mL^?1 Mo level. The method has been applied to the determination of trace amounts of Mo in biological and water samples with satisfactory results.     

测定超痕量铁的高灵敏指示反应

在稀 H2 SO4 介质中 ,1 ,1 0 -邻菲 口罗啉存在下基于 Fe( )催化过氧化氢氧化棉红的新指示反应建立了测定超痕量铁的一个新方法。方法检出限 1 .0× 1 0 - 11g/m L ,线性范围 0 .0 0～ 1 .2 ng/m L。用于井水、一次蒸馏水、黄豆、芹菜中痕量及超痕量铁的测定获得满意结果     

7-(8-羟基-3, 6-二磺基萘偶氮)-8-羟基喹啉-5-磺酸催化荧光测定痕量铜

建立了试剂7-(8-羟基-3, 6-二磺基萘偶氮)-8-羟基喹啉-5-磺酸催化荧光法测定痕量铜的新方法。采用多目标单纯形优化理论获得最佳实验条件: 0.05%试剂 1.3mL, 0.1mol/L NaOH 6.2ml, 0.1%KIO4 1.6mL, 反应时间15min。对反应机理作了详细探讨与研究, 方法用于水样、铸造铝合金样中痕量铜的测定, 结果令人满意。     

用MeSO－四（3，5－二溴－4－羟基苯基）卟啉试剂二阶导数光度法测定痕量铅

用ＭｅＳＯ－四（３，５－二溴－４－羟基苯基）卟啉试剂二阶导数光度法测定痕量铅李在均，潘教麦，徐钟隽（华东师范大学化学系，上海２０００６２）关键词：二阶导数光度法，铅的测定，人发Ｔ（ＤＢＨＰ）Ｐ是铅的高灵敏显色剂￣［１］，已用于矿样等样品中铅的测定。￣...     

Determination of trace titanium with titanium(IV)-(DBC-arsenazo)-potassium bromate system by catalytic-kinetic spectrophotometry

In a 0.080 M sulphuric acid medium, trace titanium(IV) catalyzes the discoloring reaction of DBC-arsenazo oxidized by potassium bromate and the discoloring degree is proportional to the concentration of titanium(IV) in the solution. A new catalytic-kinetic spectrophotometric method for the determination of trace titanium(IV) was developed based on this principle. At a wavelength of 516 nm, the linear range of determination of titanium(IV) is 0–2.2 μg/25 mL. The detection limit for the determination of titanium is 2.04 ng/mL. The present method has been satisfactorily applied to the determination of titanium in fish samples. The text was submitted by the authors in English.     

Development and validation of an inductively coupled plasma mass spectrometry method for quantification of levothyroxine in dissolution studies

A simple, sensitive and reproducible inductively coupled plasma mass spectrometry (ICP-MS) method for the direct determination of levothyroxine (T4), based on the analysis of iodide content, in aqueous media was developed. The sample preparation consisted of addition of antimony, as the internal standard, and dilution with a 0.5% ammonia solution. The analytes were quantified at m/z 126.90 and 120.90 for iodide and antimony, respectively. The assay was linear in the concentration range of 0.1-50 ng/mL for iodide and 0.3-100 ng/mL for T4. The method was precise and accurate with lower limits of quantification (LLOQs) of 0.1 ng/mL for iodide and 0.3 ng/mL for T4. The inter-day accuracy was >94% for both analytes and the coefficient of variation (%CV) was less than 5%. The method has successfully been used for dissolution studies of T4 formulations and holds immense promise as a simple, precise and sensitive analytical technique for T4 concentration determination in in vitro studies.