Spectrofluorimetric Determination of the Hypertensive Drug Captopril Based on Its Oxidation with Cerium(IV)

A highly sensitive and specific spectrofluorimetric method for the analysis of captopril (CAP) in the pure form and in the tablet dosage forms has been described. The method was based on the oxidation of captopril by cerium(IV) in the presence of sulphuric acid and subsequent monitoring the fluorescence of the induced Ce(III) ion produced at λ_ex = 256 nm and λ_em = 354 nm. All variables affecting the reaction conditions such as cerium(IV) concentration, type and concentration of acid medium, reaction time, diluting solvents, temperature and heating time were carefully studied and optimized. Under the experimental conditions used, an excellent linear relationship was obtained between fluorescence intensity and the concentration of CAP. A linear range of determination was verified for captopril concentrations between 0.1–1.3 μg mL^?1 and the correlation coefficient of determination was 0.9997. Quantitation and detection limits were calculated. The precision of the method was satisfactory; the values of relative standard deviations did not exceed 1.14%. No interference could be observed from the excipients and additives are commonly presented in dosage forms. The proposed method was applied successfully for the assay of the studied drug in pure form and in pharmaceutical dosage forms. Recovery experiments revealed recovery of 99.82–100.21%. The results of the analysis show a good agreement with those obtained by official method stated in the United State Pharmacopoeia.     

Chemiluminescence and Spectrofluorimetric Methods for Determination of Fluoroquinolones: A Review

Fluoroquinolones are an important and extensively studied group of compounds. Newer generations of fluoroquinolones are being developed to enhance the antimicrobial spectrum and pharmacological properties of these antimicrobials. Various analytical methods including chromatographic, voltametric, titrimetric, potentiometric, spectrophotometric, and so forth have been reported for analysis of these drugs. However luminescence and spectrofluorimetric methods continue to hold much significance as they are simple, economical, and sensitive as compared to most of the other methods. This led us to review the luminescence and spectrofluorimetric methods described for the analysis of this important class of drugs either per se, in dosage forms, or in biological fluids.     

Flow Injection Spectrofluorimetric Determination of Terbium (III) Based on Solubilizing its Ternary Complex in Micellar Solution

Abstract

A flow injection spectrofluorimetric method has been developed for the determination of terbium (III) based on solubilizing its ternary complex with pi valoyitrifluoroacetone (PTA) and trioctylphosphine oxide(TOPO) in micellar solution of nona (oxyethylene) dodecyl ether (BL-9EX). Accuracy and reproducibility are good up to 16 ng/ml of terbium (III) and 80 samples per hour can be analyzed. The relative standard deviation was less than 1.0 %. No interferences from 20-fold excesses of 11 rare earth ions were observed.     

Ultraviolet Spectrophotometric Determination of Antimony (III) Antibilharzial Compounds

Abstract

A direct UV spectrophotometric method has been developed for determination of antimony (III) antibilharzial compounds. The method has been successfully applied for the assay of five antibilharzial drugs.     

陈爱敏,魏海英*

室温下,硒(IV)与邻苯二胺配位生成黄色配合物,用环己烷萃取后,在最大吸收波长330nm处测定其吸光度。实验结果表明：硒含量在4～20 μg/mL内线性关系良好,线性方程Y=0.1999C-0.0011(R=0.9995)。最优化条件下测定硒盐中硒的含量取得满意结果。该法操作简单,设备和药品价格低廉,准确度高,稳定性好,适宜于基层实验室对食品中微量元素硒的检验。     

Kinetic-Fluorimetric Determination of Choline and Acetylcholine by Oxidation with Ce(IV)

Abstract

A kinetic fluorimetric method for the determination of choline and acetylcholine based on the oxidation of these analytes by Ce(IV) in a sulfuric acid medium yielding fluorescent Ce(III) is proposed. The calibration graph of each analyte is linear over the range 1.7x10^?5 ? 1×10^?3 M and the relative standard deviation is about 2% in both cases. The rate of appearance of Ce(III) fluorescence was found to be influenced by various processes in addition to the oxidation reaction and experiments were carried out in order to elucidate them.     

聚四氟乙烯毛细管在线富集分离痕量钌(Ⅲ)及荧光测定

利用碱性条件下聚四氟乙烯毛细管(PTFEtube)对钌-邻菲罗啉具有富集作用,建立了单道流动注射在线富集分离及检测痕量钌的荧光分析法。本方法考察了毛细管壁、流速、pH值、温度及掩蔽剂EDTA、干扰离子等因素对富集效果的影响。当浓缩液pH值为11.8,邻菲罗啉浓度为1×10-4mol/L,浓缩和洗脱速度为3.8mL/min及EDTA的浓度为2×10-2mol/L时,获得最佳结果。在优化的实验条件下,该方法在0~50ng/L范围内呈良好的线性关系,检出限为0.8ng/L(S/N=3);RSD=2.1%(n=3)。     

氢化物发生-原子荧光光谱法测定岩石中砷和锑

应用氢化物发生-原子荧光光谱法测定了岩石中砷和锑的含量。样品预先粉碎至通过孔径为0.25～0.42mm的细筛,称取此粉碎的样品0.1000～0.3000g,先于盐酸-硝酸(3+1)混合酸8mL中浸泡30 min,然后放入沸水浴中消解2 h,将溶液及不溶物一起移入50 mL容量瓶中,加水定容。移取上清液5.00mL置于10mL容量瓶中,加入100g·L~(-1)硫脲及抗坏血酸混合溶液2.5mL,用盐酸(5+95)溶液定容,分取此溶液1.0mL进样按选定的仪器条件进行分析。用20g·L~(-1)硼氢化钾溶液作为产生砷及锑的氢化物的还原剂,砷(Ⅲ)及锑(Ⅲ)的质量浓度依次在0.50～60μg·L~(-1)和0.50～80μg·L~(-1)范围内与其相应的荧光强度呈线性关系。应用此方法测定了两种岩石标准物质(GBW 07106及GBW 07108)中的砷及锑量,其测定值与认定值一致,相对标准偏差(n=5)均小于3.5%。     

Kinetics of Oxidation of Diphenylmethane and Derivatives with Ce(IV) in Aqueous Acidic Acetonitrile

In aqueous acidic acetonitrilc solution cerium(IV) oxidizes diphenylmethane (Ph₂CH₂) to produce diphenylmethanol (Ph₂CHOH) first and then benzophenone (Ph₂CO). With the organic reductant in great excess, both the Ce(IV)-Ph₂CH₂ and Ce(IV)-Ph₂CHOH rcactions follow second-order kinetics. The rates of both reactions increase nonlinearly with increasing [H⁺] or with decreasing [H₂O]. Both kinetic and spectrophotometrc results indicate that replacement of water molecules by complex formation through the phenyl or hydroxyl group plays an important role in activating the reaction. Under similar conditions, the order of relative reactivities toward Ce(IV) oxidation is PhCH₂OH > CH₃CH₂OH > Ph2CHOH > Ph₂CH₂ > PhCH₃> (Ph₂CO, C₆H₆). Mechanistic interpretations of the kinetic results are presented.     

激光热透镜光度法测定痕量锑

利用He-Ne激光,观测了锑-孔雀绿络合物的激光热透镜效应。其在苯中最低检测浓度为10ng/ml Sb,测定线性浓度范围为1～120ng/ml,测定的相对标准偏差为6.5％。本方法比常规光度法的测定灵敏度高12倍,相当于吸光度3.3×10~(-4)。     

火焰原子吸收光谱法测定粗铜中痕量铋、锑

粗铜样品经硝酸溶解,所得样品溶液中的铜离子在过量氨水中生成可溶性铜氨络离子,而铋、锑则以氢氧化铁和氢氧化镧作载体共沉淀,实现了富集铋、锑并与铜分离。基于此提出了原子吸收光谱法同时测定粗铜中的微量铋、锑。对浓盐酸的用量,硝酸铁和硝酸镧的加入量等试验条件进行了优化。铋的质量浓度在10 mg.L-1以内、锑的质量浓度在5 mg.L-1以内分别与其吸光度呈线性关系,检出限(3s)分别为0.06,0.04 mg.L-1,相对标准偏差(n=10)均小于2.0%。     

Extraction and Spectrophotometric Determination of Antimony in the Environment:

A new sensitive method for the extraction and spectrophotometric determination of antimony in the environment is described. The antimony forms a greenish yellow coloured complex with N-phenylbenzohydroxamic acid (PBHA) at 4 M HCl which is extracted from chloroform.

The Sb-PBHA complex is back extracted in 0.01 M NH₄OH and then antimony is estimated with rhodamine B in 6 M HCl media. This bluish violet coloured complex is extractable in benzene. The maximum absorbance of the antimony rhodamine B complex is observed at 565 nm. The effects of acidity, reagent concentration and diverse ions are discussed. The method is applied to the trace determination of antimony in industrial effluents and natural resources.     

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.     

Spectrofluorimetric Determination of Trace Terbium(III) Using 2,6-Bis-(1''''-phenyl-3''''-methyl-5''''-oxopyrazole-4'''') Pyridinediacyl and N-Cetylpyridium Bromide

Thechemicalpropertiesoftherareearthelementsareverysimilar,consequently.itisdifficulttofindspecificreactionsforindividualions,especiallyintheirmixtures.Duetohighersensitivityandselectivity,fluorescenceanalysisofrareearthelementshavebeenanareaofactivestudyinrecentyears.Bis(4-acylpyrazol-5-one)derivativeshavebeenwidelyappliedinlaboratoryorindustrialscaleextractionofmetalions'-'.Butthesecompoundshavebeenlittleutilizedaspotentialluminescentlabelreagents.Inthepresentpaper,thefluorescencepropertiesof…     

Antimony(III) complexes with pyridine-derived thiosemicarbazones: Structural studies and investigation on the antitrypanosomal activity

The antimony(III) complexes [Sb(2Fo4Ph)Cl₂] (1), [Sb(2Ac4Ph)Cl₂] (2) and [Sb(2Bz4Ph)Cl₂] (3) were prepared with N(4)-phenyl-2-formyl- (H2Fo4Ph), 2-acetyl- (H2Ac4Ph) and 2-benzoylpyridine (H2Bz4Ph) thiosemicarbazones. The antimony(III) complexes presented antitrypanosomal activity against the epimastigote and trypomastigote forms of Trypanosoma cruzi. Complexes (1) and (2) exhibited higher activity than the reference drugs benznidazole and nifurtimox.     

锑胁迫下腐殖质对头花蓼体内锑形态及生化特性影响

锑(Sb)是一种无延展性的有色金属,具有潜在毒性和致癌性,对心血管、呼吸系统和肝脏等都会造成危害。并且,随着近几年锑资源的持续开发,土壤中的Sb污染被广泛关注。腐殖质具有复杂结构并包含有羧基、醇羟基等多种活性官能团,对重金属在土壤中的形态转化、迁移能力以及生物可利用性具有重要影响。头花蓼作为民间常用草药并且也是贵州省特色苗药,在土壤Sb背景值极高的独山锑矿区不仅能大量生长,并且在其体内Sb含量远高于其他未受污染的陆生植物时,仍然可以表现出良好的生长状态。为了探究腐殖质对独山矿区内Sb污染土壤中头花蓼植物有效性的影响。选取贵州省独山县东峰Sb区附近Sb污染土壤与头花蓼种子作为试验样品,通过三种不同腐殖质富里酸、胡敏素、胡敏酸对Sb污染土壤进行30d的培育实验后种植头花蓼。结果表明：(1)腐殖质添加后使得头花蓼叶绿素总量整体呈现上升的趋势,加强了头花蓼光合作用。(2)头花蓼的逆境生理现象表现为：在低添加量下,胡敏素实验组与胡敏酸实验组中丙二醛含量下降,SOD酶活性升高,CAT酶活性下降;说明胡敏素和的胡敏酸在低添加量下能够有效缓解头花蓼所受到的Sb毒害;而高添加量富里酸对头花蓼有一定损害。(3)低添加量的胡敏酸能够有效缓解头花蓼植株所受到的重金属Sb、As、Cd、Cu胁迫。(4)相比于胡敏素和胡敏酸,富里酸更容易促进头花蓼体内残渣态Sb向更活跃的赋存形态转化;胡敏酸对头花蓼中的Sb赋存形态表现出了低浓度活化而高浓度钝化的现象;胡敏素则能够有效降低头花蓼体内Sb活性。     

Potentiometric Stripping Analysis at Antimony Film Electrodes

New procedures of potentiometric stripping analysis can be based on the use of antimony film electrodes and antimony(III) salts. In this paper, antimony films are generated onto carbon paste electrodes in situ and after electrolytic preconcentration of the metals to be determined, the excess antimony(III) serves as a chemical oxidant. Moreover in acidic solutions containing halide ions, the oxidation ability of antimony(III) is adequately limited because of formation of its corresponding halide complexes. Compared with similar total substitution of traditionally used mercury(II) by bismuth(III), the use of antimony(III) offers higher sensitivity in detection of heavy metals, namely, cadmium and lead.     

Regioselective radical addition of 3-oxopropanenitriles with terminal dienes promoted by cerium(IV) ammonium nitrate and manganese(III) acetate

Radical addition of 3-oxopropanenitriles to 1,3-butadiene derivatives promoted by (NH₄)₂Ce(NO₂)₆ and Mn(OAc)₃ afforded 5-ethenyl-4,5-dihydrofuran-3-carbonitriles in low to good yields. These dihydrofurans were characterised by IR, ¹H-NMR, ¹³C-NMR and HRMS spectra. All radical additions performed via CAN and Mn(OAc)₃ were occurred on the terminal double bond on dienes. A mechanism for the formation of the dihydrofurans was proposed.     

Determination of total antioxidant capacity by a new spectrophotometric method based on Ce(IV) reducing capacity measurement

Dietary antioxidants widely found in fruits and vegetables may serve the task of reducing oxidative damage in humans induced by free radicals and reactive oxygen species under ‘oxidative stress’ conditions. The aim of this work is to develop a simple, low-cost, sensitive, and diversely applicable indirect spectrophotometric method for the determination of total antioxidant capacity of several plants. The method is based on the oxidation of antioxidants with cerium(IV) sulfate in dilute sulfuric acid at room temperature. The Ce(IV) reducing capacity of the sample is measured under carefully adjusted conditions of oxidant concentration and pH such that only antioxidants and not other organic compounds would be oxidized. The spectrophotometric determination of the remaining Ce(IV) was performed after completion of reaction with antioxidants. Quercetin and gallic acid were used as standards for flavonoids and phenolic acids, respectively, and results of antioxidant measurements were reported as trolox equivalents. The developed procedure was successfully applied to the assay of total antioxidant capacity due to simple compounds such as trolox, quercetin, gallic acid, ascorbic acid, catechin, naringin, naringenin, caffeic acid, chlorogenic acid, ferulic acid, and p-coumaric acid, and due to phenolic acids and flavonoids in the arieal parts of nettle (Urtica Dioica L.). Blank correction of significantly absorbing plant extracts at 320 nm could be made with the aid of spectrophotometric titration. Plant selection was made in respect to high antioxidant content, and extraction was made with water. The proposed method was reproducible, and the trolox equivalent antioxidant capacities (TEAC coefficients) of the tested antioxidant compounds were correlated to those found by reference methods such as ABTS and CUPRAC. Since the TEAC coefficients found with the proposed method of naringin-naringenin and rutin-catechin pairs were close to each other, this Ce(IV)-based assay probably caused the simultaneous hydrolysis of flavonoid glycosides to the corresponding aglycones and their subsequent oxidation such that the hydrolysis products exhibed antioxidant capacities roughly proportional the number of -OH groups contained in a molecule.     

流动注射化学发光法测定丹皮酚

丹皮酚有解热、消炎、止痛、镇静等功效[1]。目前测定丹皮酚的方法有高效液相色谱法[2,3]、薄层色谱法[4]、毛细管气相色谱法[5]、毛细管电泳法[6,7]、紫外分光光度法[8]。流动注射是一种高度重现的进样技术[9],它同化学发光法联用,具有快速、灵敏和仪器简单等优点。用化学发光