Studies on the inclusion complex reaction and fluorescent analytical application of β-cyclodextrin with hymecromone

The inclusion complex reaction condition and the mechanism of β-cyclodextrin with hymecromone have been studied by fluorescent spectrum. The fluorescent intensity and the stability of the system can be qreatly increased in qiven condition, and the formation constant of the inclusion complex reaction has been determined too. The system can be applied to the determination of trace amounts of hymecromone, the maximum fluorescent intensity is obtained with excitation and emission wavelength at 362 nm and 452 nm, respectively. The linear range for hymecromone is 8.0×10⁻⁹ mol·L⁻¹ to 1.0×10⁻⁵ mol·L⁻¹. The detection limit is 1.8×10⁻⁹ mol·L⁻¹. A simple, rapid and highly sensitive fluorimetric method is proposed for the determination of hymecromone. The results obtained are in agreement with those given by an official method. Foundation item: Supported by the National Natural Science Foundation of China (G1999046703) Biography: Luo Zhao-fu(1947-), female, Associate professor.     

Electrochemical determination of trace amounts of lead (II) and cadmium (II) at a calix[6]arene modified carbon paste electrode

An electrochemical method for the simultaneous determination of lead(II) and Cadmium(II) with a calix[6]arene modified carbon paste electrode (CPE) has been developed. Pb²⁺ and Cd²⁺ were accumulated at the surface of the modified electrode via formation of chemical complexes with calix[6]arene, and reduced at 1.40 V. During the following anodic potential sweep, reduced lead and cadmium were oxidized, and two well-defined striping peaks appeared at about −0.60 V and −0.84 V. Compared with a bare carbon paste electrode, the calix[6]arene modified CPE greatly improves the sensitivity of determining lead and cadmium. The stripping peak currents change linearly with the concentration of Pb²⁺ 3.0×10⁻⁸–8.0×10⁻⁶ mol·L⁻¹ and with that of Cd²⁺ 6.0×10⁻⁸–1.0×10⁻⁵ mol ·L⁻¹. The detection limits of Pb²⁺ and Cd²⁺ are found to be 8.0×10⁻⁹ mol·L⁻¹ and 2.0×10⁻⁸ mol·L⁻¹, respectively. The modified carbon paste electrode was applied to determine trace levels of lead and cadmium in water samples. Comparing with that of atomic absorption spectrometry, the results suggests that the calix[6]arene modified CPE has great potential for the practical sample analysis. Foundation item: Supported by the National Natural Science Foundation of China (60171023) Biography: JI Xiao-bo (1980-), male, Master, research direction: electroanalytical chemistry.     

Fluorescence determination of tetracycline by Eu (III)/TOPO/TC system

The fluorescence intensity of the europium (III)-tetracycline (TC) complex can be greatly increased by TOPO, TBP, TTA and surfactans, among which TOPO showed the greatest enhancement. The formation of ternary complex was proposed to be responsible for the fluorescence enhancement. The Eu (III)-TOPO-TC system can be applied to the determination of trace amounts of tetracycline in urinous sample; the maximum fluorescence intensity was obtained in the pH range of 8.2∼9.5 with excitation and emission wave-lengths at 396 nm and 616 nm, respectively. The linear range for tetracycline is 6.0×10⁻⁹−5.0×10⁻⁷ mol·L⁻¹. The detection limit is 2.0×10⁻⁹ mol·L⁻¹(SNR=3). Experimental conditions and the mechanism of the enhancement effect are discussed. Supported by National Natural Science Foundation of China Huang Chunbao: born in 1958, Associate professor     

Voltammetric determination of estrogens based on the enhancement effect of surfactant at carbon paste electrode

Highly sensitive voltammetric method for the determination of estrogens, based on the enhancement effect of cetyltrimethylammonium bromide (CTAB) has been described. In the presence of CTAB, the oxidation peak currents of estrogens (estradiol, estrone, estriol, estradiol valerate and diethylstilbestrol) as the carbon paste electrode (CPE) increased significantly after open-circuit accumulation. The peak current was proportional to the concentration of estradiol over the range from 5×10⁻⁹ to 2.5×10⁻⁶ mol·L⁻¹. The detection limit was 8×10⁻¹⁰ mol·L⁻¹ at 6 min of accumulation. The total amounts of estrogens in the blood serums were determined and the average recovery was 104.92%. Under the conditions used, the electrode process of estradiol was examined the mechanism for peak current enhancement was also discussed. Foundation item: Supported by the National Natural Science Foundation of China (60171023) and the Natural Science Foundation of Hubei Province (99J060) Biography: Wu Kang-bing(1977-), male, Ph.D. candidate. research direction: bioelectrochemistry.     

Trace determination of zirconium using anodic adsorptive voltammetry at a carbon paste electrode modified with multi-walled carbon nanotubes

A carbon paste electrode modified with multi-walled carbon nanotubes （MWCNT） was prepared and the determination of ultra trace amount of zirconium based on the anodic adsorptive voltammetry of the zirconium-calcium-alizarin red S mix-polynuclear complex is described in this paper for the first time. The results showed that the sensitivity and the selectivity of the method are excellent. The second derivative linear scan voltammograms of the complex were recorded by polarographic analyzer from 200 to 1200 mV （vs. SCE） and it was found that the complex can be adsorbed on the surface of the electrode, yielding a peak at about 840 mV, corresponding to the oxidation of ARS in the complex. The peak current increases linearly with Zr （IV） concentration in the range of 6.0×10^-12--6.0×10^-11 mol. L^-1 （accumulation time 120 s）, 6.0×10^-11--2.0×10^-9 mol. L-1 （accumulation time 90 s） and 2.0×10^-9--1.0×10^-7 mol. L^-1 （accumulation time 60 s） and the detection limit （S/N = 3） is 2.0×10^-12 mol. L^-1 （accumulation time 180 s）. The procedure has been successfully applied to the determination of zirconium in the ore samples.     

Investigation of Ru （ phen ）3^2＋-Hydrazine-Ce（Ⅳ） Chemiluminescence System and Its Analytical Application

0 IntroductionThbiep ycroidmipnlee)xru ctahteinoinu mof(Ⅱ r)u t(he Rniuu(mbip,y m)3ai2n +ly) atrnids- t(r2is -,(21’ -,10-phenanthroline)ruthenium(Ⅱ) (Ru(phen)32 +) ,is a kindof sensitive analytical reagent for electrogenerated chemilumi-nescence(ECL) and chemiluminescence(CL) ,on which a par-ticular review has been presented[1]. The earliest publicationon the synthesis of Ru(bipy)32 +appeared in 1936[2], andduringthefollowing30 years ,theinvestigations relatedtothissubstance were only in…     

Fluorescence Determination of Artemisinin Using Hemoglobin as Catalyst and Pyronine B as Substrate

0 IntroductionMaalnadria siusb atr ompajicosr .he aAltrthe pmrisoibnlienmi (n qtihneghtraoopsiucs,QHS,Fig.1) is a sesquiterpene endoperoxide isola-ted fromArtemisia annuaL., an ancient Chineseherbal medicine usedfor treatment of fever and ma-laria.Studies of the structure and activity relation-ship have shownthat endoperoxide groupis essentialfor anti malarial activity of QHS and absence of thismoiety lead to completely loss in activity of thedrug. Many techniques have been developed to de…     

Application of Nanometer-Size Titanium Dioxide in Extreme-Trace V（Ⅴ） Analysis

0Introduction Vanadiumplaysanimportantroleinmodernindustry,es peciallyinsteelandchemicalindustry.Forinstance,itscompoundsarewidelyappliedintheproceduresofvitrioland petroleumchemicalmanufactureascatalyzers[14].Vanadium hasseveralvalences,butgenerallyitslowvalencesturnintohighoneseasilyinenvironment[5].BecauseV(Ⅴ)isthemost stableandpoisonousone,weoftenlayemphasisonitinenvi ronmentalpollutioncontrol.Vanadiumexistsinenvironmentalwaterwithextremelylowconcentration.Inseawateritscontentislessthan…     

Synthesis of meso-tetra-(2-chloro-4-sulfophenyl) prophyrin and spectrophotometric determination of trace amounts of cadmium

Synthesis of a new high sensitive water soluble chromogenic reagent meso-tetra-(2-chloro-4-sulfophenyl) prophyrin and the conditions for the reaction of this reagent with cadmium (I) were studied. The apparent molar absorption coefficient at 434 nm is 5.20×10⁵ L·mol⁻¹·cm⁻¹. The method has been applied to the determination of 5.0×10⁻⁹ (content by weight) Cadmium (I) in honey. Supported by the National Natural Science Foundatyion of China Xiao Ling: born in Oct. 1962, Ph.D gradute student     

Studies on reduced extent method for inhibited thermokinetics of enzyme-catalyzed reaction

The thermokinetic reduced extent equations of reversible inhibitions for Michaiels-Menten enzymatic reaction were deduced, and then the criteria for distinguishing inhibition type was given and the methods for calculating kinetic parameters,K _M,K _i andv _m were suggested. This theory was applied to inverstigate the inhibited thermokinetics of laccase-catalyzed oxidation ofo-dihydroxybenzene bym-dihydroxybenzene. The experimental results show the inhibition belongs to reversible competitive type,K _M=6.224×10⁻³ mol·L⁻¹,K _i=2.363×10⁻² mol·L⁻¹. Xiong Ya: born Sep. 1961, Ph. D. graduate student. Curent research interest is in biothermochemistry research Supported by the National Natural Science Foundation of China     

Synergistic interaction and gelation in cationic guar gum-sodium alginate system

The synergistic interaction between the cationic guar gum (the ammonium hydroxy-propyl-trimethyl chloride of guar gum) and sodium algirmte has been studied. The effects of the mass ratio of them, mixed temperature, balk salt ion concentration, incubation time and pH value on gelation were investigated. It has been observed that there was a gel strength maximum when the mass ratio was 0. 6, the mixed temperature was 70 ~C, the balk salt ion concentration was 1.0 mol ~ L-1 , the incubation time was 30 rain and the pH value was 8. Interaction between molecules of these two polysaccharides was investigated by FT-IR spectrometry.     

Sensitive Determination of DNA by RLS Enhancement of Metal Ions

0　IntroductionThequantitativeanalysisofnucleicacids,especiallythemi cro determinationofnucleicacids,isbecomingmoreandmoreimportantinmanybiologicalstudies.Recently ,apromisingspectraltechnique ,whichwasbasedonthemeasurementofen hancedresonancelightscattering (RLS) [1 ,2 ] ,hasgivenrisetostronginterestbyanalystsandbiochemistsfornucleicacidsandproteinassay[3 9] .Uptonow ,manykindscompoundshavebeenfoundRLSenhancementwhilebindingtoDNA ,andallthesecompoundsarecharacterizedofpositivechargewhicha…     

Voltammetric Response of Epinephrine at Carbon Nanotube Modified Glassy Carbon Electrode and Activated Glassy Carbon Electrode

0Introduction Epinephrine(EP)isanimportantcate cholamineneurotransmitterinthemammaliancentralnervoussystem,whichissecretedbythesu prarenalglandalongwithnorepinephrine.Itisgen erallyusedtotreathypertension,bronchialasthma,organicheartdisease,andincardiacsurgeryand myocardialinfarction[1].VariousmethodshavebeendevelopedforEPstudy,suchascapillaryelectro phoresis(CE)[2],highperformanceliquidchroma tography(HPLC)andflowinjectionanalysis(FIA)[3].Numerousobservationsontheelectro chemicalbehavio…     

Preconcentration of vanadium(V) on crosslinked chitosan and determination by graphite furnace atomic absorption spectrometry

A new method is proposed for the preconcentration of vanadium(V) with crosslinked chitosan (CCTS) and determination by graphite furnace atomic absorption spectrometry (GFAAS). The adsorption rate of vanadium(V) by CCTS was 97% at pH 4.0, and vanadium(V) was eluted from crosslinked chitosan with 2 mL 2.0 mol·L⁻¹ chlorhydric acid and determined by GFAAS. The detection limit (3σ,n=7) for vanadium (V) was 4.8×10⁻¹²g and the relative standard deviation (R.S.D) at concentration level of 2.6 μg·L⁻¹ is less than 3.6%. The method shows a good selectivity and high sensity, and it was applied to determination of vanadium(V) in oyster and water samples. The analytic recoveries are (97±5)%. Biography: Wu Wei (1975-), female, Master candidate, research direction: environmental & analytical chemistry.     

Determination of some carbonyl carboxylic acids using chemiluminescent reaction of Ru(bipy)3 2+−Ce(IV)

A coupled chemiluminescence method for the determination of some carboxylic acids was developed, based on their enhancement the chemiluminescence light emission of the reaction of tirs (2,2′-bipyridine) ruthenium(II) and Ce(IV) in sulfuric acid medium. The conditions for their determination were optimized. The following detection limits were obtained: oxalic acid, 2.67×10⁻⁸ mol/L; propandioic acid, 1.20×10⁻⁶ mol/L; pyruvic acid, 1.35×10⁻⁸ mol/L; citric acid, 5.10×10⁻⁸ mol/L; barbituric acid, 2.48×10⁻⁷ mol/L. The proposed method was successfully applied to determination of oxalic acid. The coupled chemiluminescent reaction mechanism and rate equation are proposed. Foundation item: Supported by the National Natural Science Foundation of China and the Natural Science Foundation of Hubei Province Biography: HAN He-you (1962-), male, Associate professor, phD, graduate candidate     

Myoglobin as Mimetic Enzyme and Its Analytical Application in Determination of H2O2

0 IntroductionSltougdiiceasl csoynstceermnsin gharveeac btieveen o txhyeg ei nm psopretcaienst ( oRbjOecSt) iinn bbiioo--medicine and analytical chemistry in recent years[1-4]. Manyi mportant life phenomena and diseases are relatedtotheinter-mediates of ROS[5-7].ROS have beeni mplicated as ani mpor-tant causative factor in cell damage,including apoptosis andnecrosis . Their proposed actions comprise lipid peroxidation,DNAdamage,the mitochondrial respiratory chain destructionand protein mo…     

Spectrofluorimetric method for the determination of triamcinolone acetonide

0　IntroductionTriamcinoloneAcetonide,9 fluoro 11β,2 1 dihydroxy 16α,17[(1 methylethylidene)bis (oxy) ] pregn 1,4 diene 3,2 0 dione,Mris 4 34.4 8(abr.TA ) .Itbelongstoaclassofadrenalcortexhormonedrug ,whosefunctionsareaffectionofsugarmetabolism ,anti inflammationandresistancehypersusceptibilityetc.TAcanbesuitabletorheumatoidarthritisanddermatosissuchashypersusceptibilityandneuropathicdermatitis .ThefunctionsofTAisstrongerandlongerthantriamcinolone[1 ,2 ] .ThecommonmethodsofdetectingTAm…     

Molecularly imprinted polymer for theophylline retention and molecular recognition properties in capillary electrochromatography

0　IntroductionMolecularimprinting[1 ] isatechniquebasedoncreatingcavities,inahighlycross linkedpolymermatrix ,thatcorrespondtothesizeandshapeoftheprintmolecule .Themolecularrecognitioneffectisaconsequenceofthepresenceinthepolymerizationmixtureoftemplatemoleculescapableofestab lishingnon covalentinteractionswithmonomerandcross linkers.Molecularlyimprintedpolymers (MIPs)havebeenusedaschromatographicstationaryphases[2 ,3] includingcapillaryelec trochromatography ,asselectivematerialsforbiosenso…     

Electrocatalytic oxidation of H<Subscript>2</Subscript>O<Subscript>2</Subscript> at a carbon paste electrode modified with a nickel (II)-5, 11, 17, 23-tetra-tert-butyl-25, 27-bis(Diethylcarbamoylmethoxy) calix[4] arene complex and its application

Electrochemical behavior of a carbon paste electrode (CPE) modified with nickel(II)-5, 11, 17, 23-tetra-tert-butyl-25, 27-bis(diethylcarbamoylmethoxy) calix[4]arene (Ni (II)-L) complex and its electrocatalytic activity towards the oxidation of hydrogen peroxide were investigated by cyclic voltammetric technique in a 5.0×10⁻² mol/L NaClO₄+1.0×10⁻³ mol/L NaOH solution. It was found that Ni(II)-L acts as an effective catalyst for the oxidation of hydrogen peroxide. The modified electrode exhibited a linear response over a hydrogen peroxide concentrations in the range of 2.0×10⁻⁵−1.0×10⁻⁴ mol/L with a detection limit as low as 1.0×10⁻⁶ mol/L. The relative standard deviation was 3.5% for 5 successive determinations of H₂O₂ at 1.0×10⁻⁵ mol/L. The modified electrode was used successfully in rainwater analysis. Foundation item: Supported by the Natural Science Foundation of Hubei Province (98J040). Biography: Li Chun ya(1972-), Ph. D. candidate, research direction: electroanalysis and electrosynthesis.     

毛细管电泳安培法测定班布特罗及其代谢物

以毛细管区带电泳安培检测法对大鼠血清中班布特罗及其活性代谢物特布他林的水平及药物代谢状况进行了研究.以直径300 μm的碳圆盘电极为工作电极，检测电位为1.10 V (vs. Ag/AgCl)，在0.02 mol·L^-1磷酸盐缓冲体系中(pH 7.0)，当分离电压为10 kV时两种被分析物质在16 min内可基线分离.班布特罗和特布他林浓度分别在2.0×10^-5~5.0×10^-7mol·L^-1和2.0×10^-6~5.0×10^-8mol·L^-1范围内，与峰电流呈良好的线性关系，检测限分别可达2.5×10^-7mol·L^-1和2.0×10^-8mol·L^-1.将该法直接用于班布特罗及其活性代谢物特布他林在大鼠血清中的分离与测定，无需样品预处理，分析结果令人满意.该方法具有灵敏度高、简便、易操作等优点，在临床检验和药物动力学研究中具有很好的应用前景.