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1.
张铁莉  刘锋  王俊  李克安 《化学学报》2001,59(10):1623-1627
以对羟基苯甲酸(4-HBA)为模板分子,4-乙烯吡啶(4-Vpy)为功能单体,制备得到了4-HBA分子印迹聚合物P(4-HBA),研究了该聚合物的分子识别机理,并与在同样条件下制备的水杨酸(SA)分子印迹聚合物P(SA)进行了分子识别能力的比较。结果表明:P(SA)比P(4-HBA)具有更好的分子识别能力。这是由于SA的酸性较4-HBA强,因此与碱性功能单体4-Vpy之间的静电作用更强,从而得到的复合物更稳定。本实验结果证明:功能单体与模板分子形成稳定的复合物是得到分子识别能力高的模板聚合物的前提条件。本文将有助于对分子印迹的过程以及分子印迹聚合物分子识别机理的进一步理解,并且对于根据模板分子的性质预测MIP的分子识别能力也将具有一定的指导意义。  相似文献   

2.
为了研究模板分子中作用基团的数目和位置对印迹聚合物印迹效应的影响, 分别以含有羟基数目和位置不同的羟基苯甲酸化合物3,4,5-三羟基苯甲酸(3,4,5-THBA), 3,4-二羟基苯甲酸(3,4-DHBA), 2,4-二羟基苯甲酸(2,4-DHBA)和3-羟基苯甲酸(3-HBA)为模板分子, 以丙烯酰胺为功能单体, 乙二醇二甲基丙烯酸酯为交联剂和乙腈(MeCN)为致孔剂, 采用非共价本体聚合方法制备了对应的印迹聚合物, 用色谱法评价了其分子识别性能. 结果表明, 制备的印迹聚合物对相应的模板分子均具有印迹效应, 在流动相H2O/MeCN(体积比1/99)中, 各印迹聚合物对相应的模板分子3,4,5-THBA, 3,4-DHBA, 2,4-DHBA和3-HBA的印迹因子分别为5.51, 5.55, 2.60和2.03. 通过与同样条件下制备的龙胆酸(GA)、水杨酸(SA)和对-羟基苯甲酸(4-HBA)印迹聚合物对其模板分子印迹效应的比较发现, 模板分子中作用基团数目越多, 印迹效率越高; 模板分子中作用基团-COOH和-OH的相对位置对印迹效率影响很大, 当-COOH和-OH在苯环上处于对位时的印迹效率, 高于其处于间位的印迹效率; 当-COOH和-OH在苯环上处于邻位时, 由于形成分子内氢键会降低其印迹效率. 实验还发现, 3,4-DHBA的印迹聚合物可以实现其结构类似物3,4,5-THBA和2,4-DHBA的基线分离, 为生物活性组分3,4,5-THBA的分离和测定提供了依据.  相似文献   

3.
A biomimetic potentiometric sensor for the specific recognition of methylphosphonic acid (MPA), the degradation product of nerve agents sarin, soman, VX, etc., was designed. This involves the preparation of MPA imprinted polymer particles and removal of the template by soxhlet extraction. Subsequently, the leached MIP particles were dispersed in 2-nitrophenyloctyl ether (plasticizer) and embedded in polyvinyl chloride matrix. The sensor responds to MPA in the concentration range 5 × 10−8 to 1 × 10−4 and 1 × 10−3 to 1 × 10−1 M with a detection limit of 5 × 10−8 M. The selectivity of the sensor has been tested with respect to chemical analogues such as phosphoric acid, sodium dihydrogen phosphate, organophosphorous pesticide and triazine herbicides. The utility of the sensor was tested for field monitoring of MPA in spiked ground water.  相似文献   

4.
Chen GN  Zhang L  Lin RE  Yang ZC  Duan JP  Chen HQ  Hibbert DB 《Talanta》2000,50(6):1275-1281
The electrogenerated chemiluminescent (ECL) behavior of hemin at a platinum electrode in the alkaline solution has been investigated in detail. Under the optimum conditions the linear response range of hemin is 1.0×10−5–1.0×10−8 g ml−1, the detection limit was 1.0×10−8 g ml−1, and the relative standard derivation for 1×10−7 g ml−1 hemin was 2.8%. It has been also found that hemin would catalyze the ECL of lucigenin at a platinum electrode in a neutral solution in the presence of hydrogen peroxide, the catalytic ECL intensity was linear with the concentration of hemin in the range of 1.0×10−14–1.0×10−10 g ml−1. IgG labeled with hemin was used to examine the ECL catalytic activity of hemin after conjugating to protein, and the results showed that hemin retained ECL catalytic activity when conjugated to protein.  相似文献   

5.
Campuzano S  Pedrero M  Pingarrón JM 《Talanta》2005,66(5):1310-1319
The construction and performance under flow-injection conditions of an integrated amperometric biosensor for hydrogen peroxide is reported. The design of the bioelectrode is based on a mercaptopropionic acid (MPA) self-assembled monolayer (SAM) modified gold disk electrode on which horseradish peroxidase (HRP, 24.3 U) was immobilized by cross-linking with glutaraldehyde together with the mediator tetrathiafulvalene (TTF, 1 μmol), which was entrapped in the three-dimensional aggregate formed.

The amperometric biosensor allows the obtention of reproducible flow injection amperometric responses at an applied potential of 0.00 V in 0.05 mol L−1 phosphate buffer, pH 7.0 (flow rate: 1.40 mL min−1, injection volume: 150 μL), with a range of linearity for hydrogen peroxide within the 2.0 × 10−7–1.0 × 10−4 mol L−1 concentration range (slope: (2.33 ± 0.02) × 10−2 A mol−1 L, r = 0.999). A detection limit of 6.9 × 10−8 mol L−1 was obtained together with a R.S.D. (n = 50) of 2.7% for a hydrogen peroxide concentration level of 5.0 × 10−5 mol L−1. The immobilization method showed a good reproducibility with a R.S.D. of 5.3% for five different electrodes. Moreover, the useful lifetime of one single biosensor was estimated in 13 days.

The SAM-based biosensor was applied for the determination of hydrogen peroxide in rainwater and in a hair dye. The results obtained were validated by comparison with those obtained with a spectrophotometric reference method. In addition, the recovery of hydrogen peroxide in sterilised milk was tested.  相似文献   


6.
The anodization of mercury microelectrodes was investigated in synthetic samples containing several strong and weak electrolytes at different concentrations. In particular, the effects on mercury anodization due to the presence of NaOH, HClO4, NaCl, NaI, NaF, Na2SO4, NaHCO3, Na2CO3, tartaric and citric acids, were studied in solutions containing either each species or mixtures of them, and without addition of supporting electrolyte. Some of the electrode processes studied led to linear calibration plots e.g. 1 × 10−5 − 1 × 10−4M Cl, 1 × 10−6 − 1 × 10−5M I, 5 × 10−4 − 3 × 10−3M SO42−, 5 × 10−4 − 2 × 10−2M HCO3, with typical correlation coefficients of 0.998–0.999. The anodization of mercury microelectrodes was also investigated directly in wine, rain, tap and mineral water, without pretreatment and without addition of supporting electrolyte. In the real samples only the ions Cl and HCO3 could be quantified, and the values found were in agreement, within 3–5%, with the reference values obtained by using Italian standard methods for food.  相似文献   

7.
Zhang N  Zhang X  Zhao Y 《Talanta》2004,62(5):1041-1045
The behavior of the ciprofloxacin (CPFX) complex with copper, Cu(II)L2, at a mercury electrode has been investigated in borax–boric acid buffer. The adsorption phenomena were observed by linear sweep voltammetry. The mechanism of the electrode reaction was found to be reduction of Cu(II)L2 adsorbed on the surface of the electrode by an irreversible charge transfer to metal amalgam, Cu(0)(Hg). In the presence of DNA, the formation of the electrochemically non-active complexes Cu(II)L2–DNA results in the decrease of the equilibrium concentration of Cu(II)L2 and its peak current. Under the optimum conditions, the decrease of the peak current is proportional to DNA concentration. The linear ranges are 6.67×10−8 to 1.20×10−5 g ml−1 for calf thymus DNA (ctDNA), 3.30×10−8 to 2.33×10−6 g ml−1 for fish sperm DNA (fsDNA) and 1.0×10−8 to 1.2×10−6 g ml−1 for yeast RNA. The detection limits are 5.00×10−9, 3.00×10−9 and 2.50×10−9 g ml−1, respectively. This method exhibits good recovery and high sensitivity.  相似文献   

8.
A highly sensitive and selective method is described for the determination of trace amounts of nitrite based on its effect on the oxidation of carminic acid with bromate. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of carminic acid at 490 nm after 3 min of mixing the reagents. The optimum reaction conditions were 1.8×10−1 mol l−1 H2SO4, 3.8×10−3 mol l−1 KBrO3, and 1.2×10−4 mol l−1 carminic acid at 30°C. By using the recommended procedure, the calibration graph was linear from 0.2 to 14 ng ml−1 of nitrite; the detection limit was 0.04 ng ml−1; the R.S.D. for six replicate determinations of 6 ng ml−1 was 1.7%. The method is mostly free from interference, especially from large amounts of nitrate and ammonium ions. The proposed method was applied to the determination of nitrite in rain and river water.  相似文献   

9.
UV spectra and kinetics for the reactions of alkyl and alkylperoxy radicals from methyl tert-butyl ether (MTBE) were studied in 1 atm of SF6 by the pulse radiolysis-UV absorption technique. UV spectra for the radical mixtures were quantified from 215 to 340 nm. At 240 nm. σR = (2.6 ± 0.4) × 10−18 cm2 molecule−1 and σRO2 = (4.1 ± 0.6) × 10−18 cm2 molecule−1 (base e). The rate constant for the self-reaction of the alkyl radicals is (2.5 ± 1.1) × 10−11 cm3 molecule−1 s−1. The rate constants for reaction of the alkyl radicals with molecular oxygen and the alkylperoxy radicals with NO and NO2 are (9.1 ± 1.5) × 10−13, (4.3 ± 1.6) × 10−12 and (1.2 ± 0.3) × 10−11 cm3 molecule−1 s−1, respectively. The rate constants given above refer to reaction at the tert-butyl side of the molecule.  相似文献   

10.
Li Liu  Jun-feng Song  Peng-fei Yu  Bin Cui 《Talanta》2007,71(5):1842-1848
A novel voltammetric method for the determination of β-d-glucose (GO) is proposed based on the reduction of Cu(II) ion in Cu(II)(NH3)42+–GO complex at lanthanum(III) hydroxide nanowires (LNWs) modified carbon paste electrode (LNWs/CPE). In 0.1 mol L−1 NH3·H2O–NH4Cl (pH 9.8) buffer containing 5.0 × 10−5 mol L−1 Cu(II) ion, the sensitive reduction peak of Cu(II)(NH3)42+–GO complex was observed at −0.17 V (versus, SCE), which was mainly ascribed to both the increase of efficient electrode surface and the selective coordination of La(III) in LNW to GO. The increment of peak current obtained by deducting the reduction peak current of the Cu(II) ion from that of the Cu(II)(NH3)42+–GO complex was rectilinear with GO concentration in the range of 8.0 × 10−7 to 2.0 × 10−5 mol L−1, with a detection limit of 3.5 × 10−7 mol L−1. A 500-fold of sucrose and amylam, 100-fold of ascorbic acid, 120-fold of uric acid as well as gluconic acid did not interfere with 1.0 × 10−5 mol L−1 GO determination.  相似文献   

11.
Ohura H  Imato T  Yamasaki S 《Talanta》1999,49(5):1383-1015
A rapid potentiometric flow injection technique for the simultaneous determination of oxychlorine species such as ClO3–ClO2 and ClO3–HClO has been developed, using both a redox electrode detector and a Fe(III)–Fe(II) potential buffer solution containing chloride. The analytical method is based on the detection of a large transient potential change of the redox electrode due to chlorine generated via the reaction of the oxychlorine species with chloride in the potential buffer solution. The sensitivities to HClO and ClO2 obtained by the transient potential change were enhanced 700–800-fold over that using an equilibrium potential. The detection limit of the present method for HClO and ClO2 is as low as 5×10−8 M with use of a 5×10−4 M Fe(III)–1×10−3 M Fe(II) buffer containing 0.3 M KCl and 0.5 M H2SO4. On the other hand, sensitivity to ClO3 was low when a potential buffer solution containing 0.5 M H2SO4 was used, but could be increased largely by increasing the acidity of the potential buffer. The detection limit for ClO3 was 2×10−6 M with the use of a 5×10−4 M Fe(III)–1×10−3 M Fe(II) buffer containing 0.3 M KCl and 9 M H2SO4. By utilizing the difference in reactivity of oxychlorine species with chloride in the potential buffer, a simultaneous determination method for a mixed solution of ClO3–ClO2 or ClO3–HClO was designed to detect, in a timely manner, a transient potential change with the use of two streams of potential buffers which contain different concentrations of sulfuric acid. Analytical concentration ranges of oxychlorine species were 2×10−5–2×10−4 M for ClO3, and 1×10−6–1×10−5 M for HClO and ClO2. The reproducibility of the present method was in the range 1.5–2.3%. The reaction mechanism for the transient potential change used in the present method is also discussed, based on the results of batchwise experiments. The simultaneous determination method was applied to the determination of oxychlorine species in a tap water sample, and was found to provide an analytical result for HClO, which was in good agreement with that obtained by the o-tolidine method and to provide a good recovery for ClO3 added to the sample.  相似文献   

12.
Inam R  Somer G 《Talanta》1998,46(6):1347-1355
The polarographic reduction of lead in the presence of selenite gives rise to an additional peak corresponding to the reduction of lead (Pb) on adsorbed selenium (Se) on mercury at −0.33 V. The selenium and lead content can be determined using this peak by the addition of a known amount of one of these ions first and then the second ion. The linear domain range of lead is 5.0×10−7–2.0×10−5 M and for selenium 5.0×10−7–1.0×10−5 M. Using this method 4.90×10−7 M Se(IV) and 1.47×10−6 M Pb(II) in a synthetic sample could be determined with a relative error of +2.0% and 1.8%, respectively (n=4). A recovery test after acid digestion for a synthetic sample was 97% for selenium and 96.5% for lead. The method was applied to 1 ml of digested blood, and 328±23 μg l−1 Se(IV) and 850±62 μg l−1 Pb(II) could be determined with a 90% (n=5) confidence interval.  相似文献   

13.
The collisional quenching of electronically excited germanium atoms, Ge[4p2(1S0)], 2.029 eV above the 4p2(3P0) ground state, has been investigated by time-resolved atomic resonance absorption spectroscopy in the ultraviolet at λ = 274.04 nm [4d(1P10) ← 4p2(1S0)]. In contrast to previous investigations using the ‘single-shot mode’ at high energy, Ge(1S0) has been generated by the repetitive pulsed irradiation of Ge(CH3)4 in the presence of excess helium gas and added gases in a slow flow system, kinetically equivalent to a static system. This technique was originally developed for the study of Ge[4p2(1D2)] which had eluded direct quantitative kinetic study until recently. Absolute second-order rate constants obtained using signal averaging techniques from data capture of total digitised atomic decay profiles are reported for the removal of Ge(1S0) with the following gases (kR in cm3 molecule−1 s−1, 300 K): Xe, 7.1 ± 0.4 × 10−13; N2, 4.7 ± 0.6 × 10−12; O2, 3.6 ± 0.9 × 10−11; NO, 1.5 ± 0.3 × 10−11; CO, 3.4 ± 0.5 × 10−12; N2O, 4.5 ± 0.5 × 10−12; CO2, 1.1 ± 0.3 × 10−11; CH4, 1.7 ± 0.2 × 10−11; CF4, 4.8 ± 0.3 × 10−12; SF6, 9.5 ± 1.0 × 10−13; C2H4, 3.3 ± 0.1 × 10−10; C2H2, 2.9 ± 0.2 × 10−10; Ge(CH3)4, 5.4 ± 0.2 × 10−11. The results are compared with previous data for Ge(1S0) derived in the single-shot mode where there is general agreement though with some exceptions which are discussed. The present data are also compared with analogous quenching rate data for the collisional removal of the lower lying Ge[4p2(1D2)] state (0.883 eV), also characterized by signal averaging methods similar to that described here.  相似文献   

14.
By designing a novel flow-through electrolytic cell (FEC), bromine was produced near to the surface of the platinum electrode by electrochemical oxidation of acidic KBr. The fast and weak chemiluminescence signal produced by the chemical reaction of the electrogenerated bromine with H2O2 was greatly enhanced by tetracyclines Based on these observations, a new, sensitive and simple electrogenerated chemiluminescence (ECL) method for the determination of tetracyclines was developed. Under the optimum experimental conditions, the calibration graphs are linear over the range 3.0×10−8 to 5.0×10−5 g ml−1 for tetracycline, 2.0×10−7 to 2.4×10−5 g ml−1 for oxytetracycline and 1.0×10−7 to 5.0×10−5 g ml−1 for chlortetracycline. The limits of detection (S/N=3) are 1.0×10−8 g ml−1 for tetracycline, 7.0×10−8 g ml−1 for oxytetracycline and 1.5×10−7 g ml−1 for chlortetracycline. For the determination 5.0×10−7 g ml−1 tetracycline, the relative standard deviation was <5%. The proposed method was used to determine tetracyclines in pharmaceutical formulations.  相似文献   

15.
Zhang BT  Zhao L  Lin JM 《Talanta》2008,74(5):1154-1159
Based on the chemiluminescence (CL) phenomena of folic acid in peroxomonosulfate-cobalt(II) system, a rapid and sensitive CL method was developed for determination of folic acid in pharmaceutical preparations and its urinary metabolism processes. Under the optimum conditions, the relative CL intensity was linear over the concentration ranging from 10−9 to 8 × 10−7 mol L−1 (R2 = 0.9991) with a detection limit as low as 6 × 10−10 mol L−1 (S/N = 3) and relative standard deviation was 2.63% for 2 × 10−8 mol L−1 folic acid (n = 11). This method has been successfully applied to the determination of folic acid in tablets and human urine. The blank CL emission was yielded owing to the formation of singlet oxygen molecular pair from the quenching experiment of 1,4-diazabicyclo[2.2.2]octane, and pterine-6-carboxylic acid might be the degradation intermediate in this system and it also acts an energy acceptor and sensitizes the chemiluminescence based on the studies of the CL and fluorescence spectra.  相似文献   

16.
Reartes GB  Liberman SJ  Blesa MA 《Talanta》1987,34(12):1039-1042
The acidity constants of benzidine (Bz) in aqueous solutions determined potentiometrically at 25° were Ka1 = (1.11 ± 0.08) × 10−5, Ka2 = (1.45 ± 0.12) × 10−4. The apparent mixed constants in 0.1M sodium nitrate are Ka1 = (5.37 ± 0.28) × 10−6 and Ka2 = (1.14 ± 0.09) × 10−4. The ultraviolet spectra were recorded as a function of pH and analysed with these constants to obtain the absorption spectra of H2Bz2+, HBz+ and Bz; the corresponding wavelengths of maximal absorption are 247, 273 and 278 nm, and molar absorptivities 1.63 × 104, 1.76 × 104 and 2.26 × 104 1.mole−1.cm−1.  相似文献   

17.
《Chemical physics》1995,200(3):309-318
Dynamics of electronic polarization in the vicinity of charge carriers in molecular crystals is for the first time investigated here in connection with the carrier transport and intramolecular vibronic polarization. According to standard picture it has been assumed that the electronic polarization relaxation time is extremely short, as estimated from the relation τc = τd1h/Eexc, where Eexc is the energy of the first single exciton state. In the case of anthracene (Ac) crystals, the value of τe is about 2 × 10−16 s, i.e. by several orders of magnitude shorter than a typical hopping (residence) time of charge carriers τh = 10−14 -10−13 s. It is argued that typical time of full reconstruction of the electronic polarization after individual carrier hops equals, in the slow carrier regime, approximately to td2hEexc is the width of the lowest singlet-exciton band. In Ac, this means td2 ≈ 0.73 × 10−14 s. Physical implications of this relatively high value of td2 in connection with carrier transport and molecular (vibronic) polarization are discussed.  相似文献   

18.
A new spectrophotometric flow-injection (FI) method is proposed for the determination of glucose based on the redox reaction of hydroquinone with iron(III). When a glucose solution containing quinone is passed through the immobilized glucose oxidase column introduced in FI system, quinone is reduced to hydroquinone by glucose. In the presence of 1,10-phenanthroline (phen), iron(III) is then quantitatively reduced by hydroquinone to iron(II) followed by the formation of iron(II)-phen complex (λmax=510 nm). An FI peak observed at 510 nm corresponds to the concentration of glucose. The wide dynamic range for glucose was obtained in the range of 1×10−6–1×10−3 mol l−1 at a sampling rate of 24 h−1 and the detection limit (S/N=3) was 5×10−7 mol l−1. Relative standard deviations were 0.78, 0.44 and 0.23% (n=5) for 5×10−6, 5×10−5 and 5×10−4 mol l−1 of glucose, respectively. The proposed method was successfully applied to the determination of glucose in control blood sera, human blood plasma and wine.  相似文献   

19.
Electrochemical studies of famotidine were carried out using voltammetric techniques: cyclic voltammetry, linear sweep and square wave adsorptive stripping voltammetry. The dependence of the current on pH, buffer concentration, nature of the buffer, and scan rate was investigated. The best results for the determination of famotidine were obtained in MOPS buffer solution at pH 6.7. This electroanalytical procedure enabled to determine famotidine in the concentration range 1 × 10−9–4 × 10−8 mol L−1 by linear sweep adsorptive stripping voltammetry (LS AdSV) and 5 × 10−10–6 × 10−8 mol L−1 by square wave adsorptive stripping voltammetry (SW AdSV). Repeatability, precision and accuracy of the developed methods were checked. The detection and quantification limits were found to be 1.8 × 10−10 and 6.2 × 10−10 mol L−1 for LS AdSV and 4.9 × 10−11 and 1.6 × 10−10 mol L−1 for SW AdSV, respectively. The method was applied for the determination of famotidine in urine.  相似文献   

20.
利凡诺分子模板聚合物的吸附与识别特性研究   总被引:25,自引:3,他引:22  
以利凡诺药物为模板分子,α-甲基丙烯酸为功能基单体,乙二醇二甲基丙烯酸酯为交联剂,选用分子模板技术,合成了一种新的具有类似于酶或药物受体结合部位为结构特征的分子模板聚合物.研究了它对利凡诺和其它底物的吸附特性和选择性识别能力.结果表明,与组成相同的非模板聚合物相比,利凡诺分子模板聚合物有较大的吸附性能和高度的选择性及识别能力.静电作用和氢键在吸附和识别过程中发挥着重要作用.  相似文献   

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