Synthesis and properties of 10-hydroxy-10-oxo-10<Emphasis Type="Italic">H</Emphasis>-10λ<Superscript>5</Superscript>-phenoxaphosphine-2,8-dicarboxylic acid and related polybenzoimidazoles

Oxidation of 10-hydroxy-2,8-dimethyl-10H-10⁵-phenoxaphosphine 10-oxide (1) with potassium permanganate in an alkaline medium afforded 10-hydroxy-10-oxo-10H-10⁵-phenoxaphosphine-2,8-dicarboxylic acid (2). The latter exists as a stable crystal hydrate containing two water molecules. With the aim of examining the possibility of performing the synthesis of polybenzoazoles based on acid 2, the model reaction of the latter with o-phenylenediamine in polyphosphoric acid (PPA) was studied. New high-molecular-weight phosphorus-containing polybenzoimidazoles were prepared by the reaction of 2 with various aromatic tetraamines in PPA and Eatons reagent.     

Adsorptive Stripping Voltammetric Determination of Albendazole at a Hanging Mercury Drop Electrode

ABSTRACT

Albendazole is determined by differential-pulse adsorptive cathodic stripping voltammetry at a hanging mercury drop electrode using the reduction peak of its copper(II) complex at ?0.28V at an accumulation potential 0.0V vs. Ag/AgCl electrode. The optimum conditions of pH, accumulation potential and accumulation time were studied. The calibration graph for the determination of albendazole was linear in the range 3.0X10^?8 - 9X10^?7M with a relative standard deviation of 2.8%. The detection limit was 1.0X10^?8M after 180s accumulation at 0.0V. The effect of common excipients and metal ions on the peak height of albendazole was studied. The presence of Cu²⁺ ions forms a stable complex with albendazole which is strongly adsorbed at the mercury electrode surface. The method was applied to the determination of the drug in commercially available dosage forms.     

Sub-Microdetermination of Antimony (Iii) and Antimony (V) In Natural and Polluted Waters and Total Antimony In Biological Materials By Flameless Aas Following Extractive Separation With N-P-Methoxyphenyl-2-Furylacrylohydroxamic Acid

Abstract

Antimony (III) was separated from antimony (V) by extractive separation from 2–10^?6 M HC1 media with N-p-methoxyphenyl-2-furylacrylohydroxamic acid (MFHA) in chloroform and determined by graphite furnace atomic absorption spectroscopy at 2600°C using copper as matrix modifier. Antimony (V) was subsequently reduced to the trivalent form with acidic (-1M HC1) potassium iodide solution and determined as above. the mutual tolerance between antimony (III) and antimony (V) in the present mothod was very high-either of the species could be determined in presence of 15 times higher concentration of the other species. the sepatation-AAS determination system enabled accurate differential analysis of the metalloid in natural/ polluted waters down to 10^?2 ppb (ug 1^?1) levels. the method was also applied to the analysis of antimony in vehicle exhaust particulates, plant tissues, and animal tissues. the method was validated by analysing several certified reference materials with and without standard addition of antimony. MFHA was chosen from amongst thirteen new hydroxamic acids.     

Study on Complex of Re(III) with 3, 5-Br2-DMPAP by Electrochemistry and Application

ABSTRACT

The electrochemical character of a new reagent, 2-(3, 5-Dibrome-2-pyriclyiazo)-5-dimethylaminophenol(3, 5-Br₂-DMPAP) was studied in HAc-NaAc medium at pH=3.50. In single sweep polarography, the reduction potential of the complex wave (-1.05V) is more negative than that of the free ligand(-1.01V). The complex wave was proven to be an adsorption wave. The composition ratio of the complex was formed to be 1:1 using a molar ratio method. The current of the adsorptive peak at-1.05V was directly proportional to the concentration of Re(III) in the range of 1.5× 10^?8～7.0×10^?5mol/l. The microamount of Re in several samples of Chinese cigarettes determined with satisfactory accuracy and precision.     

Simultaneous quantitative estimation of oxybenzone and 2-ethylhexyl-4-methoxycinnamate in sunscreen formulations by second order derivative spectrophotometry

Simultaneous determination of 2-ethylhexyl-4-methoxycinnamate (OMC) and oxybenzone (OB) in commercial sunscreen formulations has been achieved by using second order derivative spectrophotometry. The analytical methodology described does not require elaborate pretreatment of samples. The results obtained could be validated by reverse phase HPLC assay by using isocratic methanol: water (88: 12) solvent system. The sensitivity of the developed derivative spectrophotometry method was determined to be 9.0 × 10⁻³ L/mg for OB and 9.56 × 10⁻³ L/mg for OMC. The limit of instrumental detection (LOD) was determined to be 0.6 mg/L for OB and 1.38 mg/L for OMC with relative standard deviation of 0.001 and 0.004 for OB and OMC respectively. The method developed can be used for quick assay of commercial sunscreens. The article is published in the original.     

Spectrophotometric Determination of Trace Amounts of Titanium in Geochemical and Metallurgical Samples

Abstract

The reaction between cyclohexan-1,2-dione bissalicyloylhydrazone and titanium(IV) has been studied spectrophotometrically. An orange complex (λ = 470 nm, ? = 1.49 × 10⁴ 1.mol^?1.cm^?1) is quickly formed at pH 1–2.5 in a 3+2 V/V ethanol/water medium. Interferences (more than 65 species) have been investigated. In presence of some masking agents most of metal ions do not interfere. The orange complex has been satisfactorily used for the determination of titanium in amphibolites, granites, suspended matter, Portland cement, bauxite, cast iron and duraluminium alloy. The results are compared with those obtained using AAS and ICP methods.     

系列缩水甘油醚类β-环糊精衍生物的合成及结构表征

以苯基缩水甘油醚、邻甲基酚缩水甘油醚及苯甲基缩水甘油醚(1～3)和β-环糊精为原料, 分别在弱碱水溶液(1.5%)和强碱水溶液(30%)中制备出系列缩水甘油醚类β-环糊精衍生物, 所得产物用自制硅胶色谱柱分离, 以V(正丙醇)∶V(水)∶V(浓氨水)＝6∶3∶1作为硅胶色谱柱分离纯化的洗脱剂, 得到单2位取代的苯氧基(或邻甲基苯氧基或苯甲氧基-2-羟丙基-β-环糊精(1a～3a)和单6位取代的苯氧基(或邻甲基苯氧基)-2-羟丙基-β-环糊精(1b～2b). 所得产品用薄层色谱、红外光谱、质谱和核磁共振波谱等手段进行了表征.     

Ultramicro Analysis of Reducing and Non-Reducing Sugars by Liquid Chromatography

Abstract

A post-column detection system for ultramicro amount of sugars has been developed using taurocyamine as the labelling reagent. Less than 10 pmol of reducing sugars were determined by this HPLC system. Non-reducing sugars were detected by the addition of periodate to the reagent.

Modification of the reaction reagent components made this detection system feasible to apply to various methods for separation of carbohydrates using pure water, acetonitrile/water mixtures, borate buffer or aqueous sodium hydroxide as the eluent.     

Electrochemical and Spectral Behaviour of a New Cardiotonic Drug (Sulmazole)

Abstract

Spectrophotometric and electrochemical properties of sulmazole are studied. The acid-base constants are calculated (pk_a1 = 3.88 ± 0.04 and pK_a2 = 11.39 ± 0.06).

The drug can be spectrophotometrically determined between 4.01 × 10^?5 M and 4.02 × 10^?6 M at 327 nm with relative errors lower than 0.4 % and relative standard deviations lower than 2.0 %.

The electrochemical reduction of sulmazole was investigated by DCT, DP polarography and cyclic voltammetry. Reduction of the drug was carried out in two irreversible steps using Britton-Robinson bu ffer (pH < 7). Half-wave potentials for 1.53 × 10^?4 M sulmazole at pH 2.5 are -0.825 V and -0.995 V (versus Ag/AgCl/3M KC1).

Two different methods for determination of sulmazole in tablets are proposed.     

Separation of Xanthine Derivates by High Pressure Liquid Chromatography and Application to Plasma Analysis

Abstract

High pressure liquid chromatography (HPLC) methods were developed for separation and plasma analysis of ten xanthine derivates. Separation was evaluated on silica column and on three different reverse phase columns, with optimum conditions obtained on C₆ spherisorb column using isocratic elution with phosphate buffer 10^?2 M, pH 2.7 - acetonitrile mixture (80/20 V/V). Determination of these xanthine derivates in plasma for therapeutic control was studied.     

Absorptiometric Determination of Acetylsalicylic Acid in Aqueous Ethanolic Solution

Abstract

Acetylsalicylic acid (ASA) was found to be quite soluble and quite stable in a 50/50% volume/volume water–ethanol solution. In this solution, a well-defined spectrum with a maximum absorbance, λ_max, of 276 nm of ASA was observed, and a molar absorptivity, ε, of 1.1 × 10³ M-cm was determined. These characteristic physical properties were used to determine ASA concentration in different brands of aspirin. The λ_max and the ε of salicylic acid were also determined. The characteristic values determined were 300 nm and 3.83 × 10³ M-cm, respectively. In this solution and using the method developed here, the concentrations of salicylic acid and ASA in a given aspirin formulation can be determined simultaneously.     

具有聚集荧光增强性质的双(4-二乙氨基水杨醛)缩偶氮二甲酰肼二丁基锡的合成和晶体结构

在甲醇溶液中,卡巴肼、(4-二乙氨基)水杨醛和二乙酸二丁基锡"一锅法"反应,合成了一个新颖的基于双(4-二乙氨基水杨醛)缩偶氮二甲酰肼(L)的七配位有机锡配合物[Sn(L)(n-butyl)_2]n(T)。经元素分析、IR、(1H,119Sn,13C)NMR和X射线衍射晶体结构表征,T的晶体属单斜晶系C2/c空间群,中心锡周围由双(4-二乙氨基水杨醛)缩偶氮二甲酰肼的O,N配位原子占据赤道位置和2个丁基占据顶端位置形成畸变五角双锥构型。通过烯醇式氧原子的桥联配位作用,T向一维带状无限扩展产生"竹筏状"超分子结构。配合物T在二甲基甲酰胺、四氢呋喃、乙醇、甲醇和甲苯有机溶剂及其有机溶剂-水混合物中具有强荧光发射峰,当含水量的体积分数在0～10%(V/V)时具有良好的聚集荧光增强效应,含水量大于10%(V/V)时发生荧光淬灭。     

Anodic Stripping Voltammetric Determination of Mercury in Water Using a Chitosan‐Modified Carbon Paste Electrode

Abstract

This paper describes the preparation and electrochemical application of a modified carbon paste electrode with chitosan for the determination of Hg(II) ions in water using anodic stripping voltammetry. Experimental parameters, including the pH of the supporting electrolyte, time and potential of accumulation and scan rate were investigated. The best voltammetric response was observed for a paste composition of 60% (m/m) of graphite powder, 20% (m/m) of chitosan and 20% (m/m) of mineral oil, with 0.1 mol/l NaNO₃ solution at pH 6.3 as supporting electrolyte, a preconcentration potential of ?0.2 V, preconcentration time of 270 s and a scan rate of 25 mV/s. Under these optimal experimental conditions, the voltammetric signals were linearly dependent on the Hg(II) concentration in the range of 9.99×10^?7 to 3.85×10^?5 mol/l with a detection limit of 6.28×10^?7 mol/l. Three “spiked” samples of water were evaluated using the proposed sensor, and results agreed with those obtained by a reference method at the 95% confidence level.     

Extraction equilibria and spectrophotometric determination of vanadium(V) with 4-nitrocatechol and the ion-pair reagent thiazolyl blue tetrazolium

The formation and liquid-liquid extraction of a yellow ternary complex of vanadium(V) with 4-nitrocatechol (NC) and the ion-pair reagent Thiazolyl Blue Tetrazolium ⨑ub;3-(4,5-dimethyl-2-thiazol)-2,5diphenyltetrazolium bromide, MTT⫂ub; with 1: 2: 3 stoichiometry (V: NC: MTT) was studied. The optimum extraction conditions (pH, concentration of the reagents, extraction time), spectrophotometric parameters of the extract and key constants (extraction constant, association constant, distribution constant) were determined. Beer’s law was obeyed for concentrations ranging from 0.12 to 1.2 μg/mL of vanadium(V) with a molar absorptivity of ɛ = 3.13 × 10⁴ L/mol cm at λ_max = 400 nm. The effect of diverse ions was studied and extraction-spectrophotometric procedures for determination of vanadium in catalysts and steels were proposed.     

Mixed Ligand Complexes of Vanadium(V): Extraction With Some New Hydroxamic Acids and Application in Steel.,Rock and Environmental Anaysis

Abstract

Five new substitued hydroxamic acids are used for extraction and spectrophotometric determination of vanadium(V) in trace amounts. the binary complex of vanadium (V) with H-p-ciloropheny 1-3,4,5-trimethoxycinnamohdroxamic acid (PTCHA) and the mixed ligand complex of vanadium (V) with N-p-cinlorpheny-p-chlorophenoxyisobutyrohydroxamic acid (PP3HA) and thiocyanete were studied. The molar absorbtivities of the bluish violet vanadium(V) hydroxamate and mixed ligand complexes are 6.9 × 10³ and 1.1 × 10⁴ cm³ mol^?3 cm^?1, respectively. The vanadium is also determined with AAs and the method is applied for its determination in steel. alloy, rock and environmental samples.     

Quantitative Analysis of Meclizine in Tablet Formulations by HPLC

Abstract

A simple, rapid and precise high-performance liquid chromatographic assay of meclizine in tablets has been developed. Reversed-phase chromatography was conducted using a mobile phase of acetonitrile and water (30% V/V) and detection at 230 nm. The recovery and coefficient of variation from six placebo tablets containing 25 mg of meclizine were 100.5% and 0.84%, respectively. Replicate regression analyses of three standard plots in the concentration range of 1–12 mcg/ml obtained on three different days gave a correlation coefficient >0.998 and the coefficient of variation of the slopes <1%. The assay was precise within day and between days as indicated by ANOVA test. The recoveries from 10 replicate tablets of the two different commercial meclizine brands were 98.5 and 100.7% of the label amount and their coefficients of variation were 1.16 and 1.71%.     

Inorganic arsenic speciation in various water samples with GFAAS using coprecipitation

A simple, economic and sensitive method for selective determination of As(III) and As(V) in water samples is described. The method is based on selective coprecipitation of As(III) with Ce(IV) hydroxide in presence of an ammonia/ammonium buffer at pH 9. The coprecipitant was collected on a 0.45 µm membrane filter, dissolved with 0.5 mL of conc. nitric acid and the solution was completed to 2 or 5 mL with distilled water. As(III) in the final solutions was determined by graphite furnace atomic absorption spectrometry (GFAAS). Under the working condition, As(V) was not coprecipitated. Total inorganic arsenic was determined after the reduction of As(V) to As(III) with NaI. The concentration of As(V) was calculated by the difference of the concentrations obtained by the above determinations. Both the determination of arsenic with GF-AAS in presence of cerium and the coprecipitation of arsenic with Ce(IV) hydroxide were optimised. The suitability of the method for determining inorganic arsenic species was checked by analysis of water samples spiked with 4–20 µg L^?1 each of As(III) and As(V). The preconcentration factor was found to be 75 with quantitative recovery (≥95%). The accuracy of the present method was controlled with a reference method based on TXRF. The relative error was under 5%. The relative standard deviations for the replicate analysis ( n?=?5) ranged from 4.3 to 8.0% for both As(III) and As(V) in the water samples. The limit of detection (3σ) for both As (III) and As(V) were 0.05 µg L^?1. The proposed method produced satisfactory results for the analysis of inorganic arsenic species in drinking water, wastewater and hot spring water samples.     

Nafion‐Modified Glassy Carbon Electrode for Trace Determination of Indium

Abstract

A new method for determination of trace indium is proposed by the adsorption stripping voltammetry (ASV) using a Nafion‐modified glassy carbon electrode (NMGCE). This chemically modified electrode (CME) shows a better stability. A sensitive oxidation peak was observed, and the anodic peak potential is ca. ?0.548 V (vs. SCE). The influences of various experimental parameters on the current peak were completely studied. Under the optimized condition, the method has been applied to the determination of indium in water samples. There is a good linear relationship between the peak current (i_p) and indium(III) concentration in the range of 1.0×10^?9–1.0×10^?7 mol/l, and the limit of detection is 7.5×10^?10 mol/l.     

A ratiometric fluorescent probe for zinc ions based on the quinoline fluorophore

A ratiometric fluorescent zinc probe 1 of carboxamidoquinoline with a carboxylic acid group was designed and synthesised. Probe 1 exhibits high selectivity for sensing Zn²⁺; about a 13-fold increase in fluorescence emission intensity and an 82?nm red-shift of fluorescence emission are observed upon binding Zn²⁺ in EtOH/H₂O (1?:?1, V/V) solution. The ratiometric fluorescence response is attributed to the 1?:?1 complex formation between probe 1 and Zn²⁺ which has been utilised as the basis for the selective detection of Zn²⁺. The analytical performance characteristics of the proposed Zn²⁺-sensitive probe were investigated. The linear response range covers a concentration range of Zn²⁺ from 2.0?×?10^?6 to 5.0?×?10^?5?mol?L^?1 and the detection limit is 2.7?×?10^?7?mol?L^?1. The determination of Zn²⁺ in both tap and river water samples shows satisfactory results.     

Rapid Assay of Hypothalamic Aromatase Using High Performance Liquid Chromatography

Abstract

A rapid assay for hypothalamic aromatase has been developed using HPLC. Each assay tube contained rat anterior hypothalamus homogenized in Na phosphate buffer (pH 7.0), NADPH regenerating system, unlabelled estradiol and estrone, and 10 μCi of ³H-androstenedione. After agitation at 37°C for 3 hours, the reaction mixture was extracted with CH₂Cl₂, partitioned between 90% methanol and hexane, and the methanol layer chromatographed on a Waters 10μ C-18 Radial-PAK column using acetonitrile/water (70:30). The estrogens were collected together and rechromatographed with THF/water (35:65). The estrone peak was collected, and the ³H-estrone produced was determined by liquid scintillation. The estrone collected from the second chromatographic step was found to be at least 95% pure by methylation and rechromatography. Using the HPLC procedure, enzymatic ³H-estrone formation was found to be linear in a time and protein dependant manner.