Analytical Communications最新文献

{"title":"Fluorescence polarisation of green fluorescent protein (GFP). A strategy for improved wavelength discrimination for GFP determinations","authors":"A. Knight, N. Goddard, P. Fielden, M. Barker, N. Billinton, R. Walmsley","doi":"10.1039/A901326A","DOIUrl":"https://doi.org/10.1039/A901326A","url":null,"abstract":"The fluorescence of green fluorescent protein (GFP), present both within whole yeast cells and in protein extracts from yeast cells, has been observed to be significantly polarised. Fluorescence polarisation is proposed as a useful technique to allow some discrimination between GFP fluorescence and that of other interfering species in cell or media matrices, which have fluorescence bands that overlap those of GFP, which should lead to improved resolution and limits of detection. The method has been tested by discriminating between the fluorescence of GFP in cell extracts and added fluorescein, both of which fluoresce brightly at the same wavelength. The flow-through instrumentation incorporating an argon-ion laser developed for this work is also described.","PeriodicalId":7814,"journal":{"name":"Analytical Communications","volume":"27 1","pages":"113-117"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84823310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fluorescent indicators for inositol 1,4,5-trisphosphate based on bioconjugates of pleckstrin homology domain and fluorescent dyes","authors":"K. Hirose, H. Takeshima, M. Iino","doi":"10.1039/A901274E","DOIUrl":"https://doi.org/10.1039/A901274E","url":null,"abstract":"Bioconjugates of fluorescent dyes and the recombinant pleckstrin homology (PH) domain of phospholipase Cδ1 were produced with the aim of developing a method to quantify inositol 1,4,5-trisphosphate (IP3) in biological samples. We replaced Cys-96 of the PH domain with Ser while retaining Cys-48 to which thiol-reactive fluorescent dyes can be coupled specifically. Acrylodan- and Dapoxyl-labelled C96S PH domain mutants exhibited fluorescence upon UV illumination with an emission peak at wavelengths of 505 and 514 nm, respectively. IP3 induced decreases in the fluorescence intensity with a red shift in the emission spectra. The dissociation constants (Kds) of the acrylodan- and Dapoxyl-labelled PH domains for IP3 were 659 and 586 nM, respectively. An additional mutation (C96S/V58K) in the PH domain decreased the Kds by ≡50%, providing a more sensitive method. The results indicate that these bioconjugates are promising as fluorescent indicators for IP3 quantification.","PeriodicalId":7814,"journal":{"name":"Analytical Communications","volume":"38 1","pages":"175-177"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90742611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rapid determination of enzyme purity by a microdialysis-based assay","authors":"S. Richardson, G. Nilsson, N. Torto, L. Gorton, T. Laurell","doi":"10.1039/A901895F","DOIUrl":"https://doi.org/10.1039/A901895F","url":null,"abstract":"Microdialysis was shown to be useful as a fast on-line sampling method for determining the purity of starch hydrolysing enzymes. The enzymes were characterised using their hydrolytic properties. β-Amylases and pullulanases from different sources and/or manufacturers were investigated, with maltose, maltoheptaose, pullulan, and potato amylopectin starch (PAP) as substrates. The hydrolysis products were sampled via an on-line microdialysis probe and determined in a high-performance anion-exchange chromatographic (HPAEC) system. Comparison between the expected (theoretical) hydrolysis products with those obtained in the experiments made it possible to determine impurities in the enzymes. Two of the β-amylases and one pullulanase released unwanted hydrolysis products, indicating trace impurities in the enzyme preparation. Microdialysis sampling allows on-line sampling and eliminates separate sample preparation and clean-up steps. On-line microdialysis coupled to a HPAEC system is therefore a fast and simple technique for analysing enzyme hydrolysates.","PeriodicalId":7814,"journal":{"name":"Analytical Communications","volume":"12 1","pages":"189-193"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91087231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The simultaneous separation of twenty-one metal cations using capillary isotachophoresis with on-column conductivity detection","authors":"J. E. Prest, P. Fielden","doi":"10.1039/A905511H","DOIUrl":"https://doi.org/10.1039/A905511H","url":null,"abstract":"The possibility of using capillary isotachophoresis coupled with on-column conductivity detection for the separation of complex metal cation mixtures has been demonstrated. The simultaneous separation of a mixture of the 21 metal cations Ca2+, Mg2+, Mn2+, Co2+, Ni2+, Zn2+, Be2+, La3+, Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Cu2+, Y3+, Ho3+, Er3+, Tm3+, Yb3+ and Lu3+ has been reproducibly achieved using aqueous electrolytes. Calibration curves were produced for two of these ions, Co2+ and Er3+. A linear response was observed over the range from 0.02 mmol dm–3 to 1.70 mmol dm–3 for cobalt and 0.05 mmol dm–3 to 1.00 mmol dm–3 for erbium. These curves allowed limits of detection to be calculated as 0.015 mmol dm–3 for cobalt and 0.045 mmol dm–3 for erbium.","PeriodicalId":7814,"journal":{"name":"Analytical Communications","volume":"13 1","pages":"333-335"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77699883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electrochemical control of solid phase micro-extraction using unique conducting polymer coated fibers","authors":"Thompson P. Gbatu, Ozcan Ceylan, K. Sutton, J. F. Rubinson, J. Caruso, H. B. Mark","doi":"10.1039/A901991J","DOIUrl":"https://doi.org/10.1039/A901991J","url":null,"abstract":"The use of a solid phase micro-extraction (SPME) method with poly(3-methylthiophene) coated platinum micro-fiber electrodes to extract arsenate ions from aqueous solutions without derivatization is described. The fibers were fabricated by cycling the working electrode between –0.20 and +1.7 V (vs. Ag/AgCl) in an acetonitrile solution containing 50 mM 3-methylthiophene monomer and 75 mM tetrabutylammonium tetrafluoroborate (TBATFB) electrolyte. All electrochemical procedures (extraction and expulsion) were conducted in a three-electrode system. After fabrication, the conducting polymer film was immersed in the sample solution and converted to its oxidized, positively charged form by applying a constant potential of +1.2 V with respect to Ag/AgCl reference electrode. Arsenate ions migrated into the film to maintain electroneutrality. Upon subsequent reversal of the potential to –0.60 V vs. Ag/AgCl, the polymer film was converted to its reduced, neutral form and the arsenate ions were expelled into a smaller volume (200 µL) of de-ionized water for analysis using flow injection with inductively coupled plasma mass spectrometric (ICP-MS) detection.","PeriodicalId":7814,"journal":{"name":"Analytical Communications","volume":"7 1","pages":"203-205"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78261015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An optically sensitive membrane for pH based on swellable polymer microspheres in a hydrogel","authors":"M. Rooney, W. Seitz","doi":"10.1039/A902183C","DOIUrl":"https://doi.org/10.1039/A902183C","url":null,"abstract":"A membrane that is optically sensitive to pH has been prepared by suspending aminated polystyrene microspheres in a hydrogel. Light crosslinked poly(vinylbenzyl chloride) microspheres with diameters about 1 µm were prepared by dispersion polymerization and aminated with diethanolamine. These microspheres were suspended in a solution of hydroxyethylmethacrylate, which was then polymerized to form a hydrogel. The resulting membranes are turbid because the refractive index of the microspheres is greater than the refractive index of the hydrogel. Turbidity decreases with increasing wavelength. The turbidity of the membranes is greater in a base than in an acid. In acid, protonation of the amine group causes the polymer microspheres to swell. Swelling affects turbidity, both by increasing microsphere diameter and by reducing the microsphere refractive index so that it is closer to the refractive index of the hydrogel. The latter effect dominates in the membranes described here. A simplified theory to describe this behavior yields values that are consistent with observations. These membranes can be used for optical sensing in the visible and near-infrared regions, including wavelengths used for fiber optics telecommunications. They are expected to have excellent long-term stability. However, the microspheres prepared for this study respond very slowly because they are not sufficiently porous to allow easy analyte access to the interior of the polymer.","PeriodicalId":7814,"journal":{"name":"Analytical Communications","volume":"91 1","pages":"267-270"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75846175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synthesis and preliminary evaluation of a molecularly imprinted polymer selective for artificial phenolic estrogenic compounds","authors":"J. Tarbin, M. Sharman","doi":"10.1039/A900197B","DOIUrl":"https://doi.org/10.1039/A900197B","url":null,"abstract":"A molecularly imprinted polymer has been prepared using a hexestrol template. The polymer was synthesised using diethylaminoethyl methacrylate (DAEM) as functional monomer and trimethylolpropane trimethacrylate as cross-linking monomer via a photoinitiated addition polymerisation. An equivalent blank polymer was also synthesised in the absence of the template compound. After packing into a stainless steel column (150 × 4.6 mm id), retention and elution of the template and related compounds were evaluated by high-performance liquid chromatography (HPLC). The results showed that the material synthesised in the presence of hexestrol demonstrated a selectivity towards compounds containing the stilbene carbon backbone (diethylstilbestrol, dienestrol, hexestrol).","PeriodicalId":7814,"journal":{"name":"Analytical Communications","volume":"18 1","pages":"105-107"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82664894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on Acridine Orange dimer as a new fluorescent probe for the determination of protein","authors":"Luo Yunjing, Shen Hanxi","doi":"10.1039/A900601J","DOIUrl":"https://doi.org/10.1039/A900601J","url":null,"abstract":"A nonfluorescent dimer of Acridine Orange is formed in situ in the presence of the anionic surfactant, sodium dodecyl sulfate (SDS). Proteins labeled with Acridine Orange dimer (AOAO) show a greatly enhanced fluorometric activity compared with that of AOAO. Based on this, a new, fast and sensitive fluorescent probe for the determination of proteins was developed. The linear range of this assay is 0.66–39.8 µg mL–1. For the detection of proteins in human serum, this method gave values close to that of the conventional Coomassie Brilliant Blue (CBB) method, but the sensitivity of the method is much superior to that of the CBB method. The detection limit for BSA was 0.08 µg mL–1.","PeriodicalId":7814,"journal":{"name":"Analytical Communications","volume":"73 1","pages":"135-137"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84307397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Plant tissue-based chemiluminescence flow biosensor for oxalate","authors":"W. Qin, Z. Zhang, Youyuan Peng, Baoxin Li","doi":"10.1039/A905916D","DOIUrl":"https://doi.org/10.1039/A905916D","url":null,"abstract":"A novel plant tissue-based chemiluminescence (CL) biosensor for oxalate combined with flow injection analysis is proposed in this paper. The analytical reagents involved in the CL reaction, including luminol and cobalt(II), were both immobilized on an ion exchange resin column, while the biological material spinach tissue was packed in a mini-glass column. By the oxalate oxidase-catalyzed reaction in the plant tissue column, hydrogen peroxide was produced, which could react with luminol and cobalt(II) being released from the ion exchange column by hydrolysis to generate a CL signal. The CL emission intensity was linear with oxalate concentration in the range 0.6–100 µM and the detection limit was 0.2 µM. The biosensor was stable for 300 determinations and a complete analysis, including sampling and washing, could be performed in 2 min with a relative standard deviation of less than 5%.In recent years, traditional enzyme biosensors have been challenged by biosensors which use new biocatalytic materials, including animal and plant tissues1–3 and microorganisms.4–6 The catalytic function of these types of biosensors is due to the enzymes linked with metabolic pathways which exist either in the cytoplasmic membranes or directly inside the cells of these materials. Compared to biosensors with immobilized isolated and pure enzymes, such biosensors with immobilized tissues or whole cells show potential advantages of low cost, high stability, and a high level of enzyme activity. So far, most of them are bioselective membrane electrodes, in which the biocatalytic layer is usually retained physically at the detecting electrode surface with a support membrane and the analyte is sensed by diffusing through the test solution to the inner detector surface. However, these sensors often suffer from problems of long response time, low sensitivity and complex sensor assembly.Flow injection chemiluminescence (CL) analysis is becoming increasingly important in various fields for its high sensitivity, rapidity, simplicity and feasibility. Nowadays, CL flow sensing systems with immobilized reagents have received much attention and many applications have appeared in the literature.7–11 In these systems, analytes are detected by the CL reactions with the immobilized reagents directly or with the dissolved reagents which are released from the immobilized substrates by appropriate eluents. In this paper, a new type of biosensor, based on a plant tissue reactor, with flow injection CL detection for the determination of oxalate is proposed. It is prepared by using a spinach tissue column as the source of oxalate oxidase to catalyze the oxidation reaction of oxalate producing hydrogen peroxide, which is then detected by the CL reaction with luminol and cobalt(II) bleeding from an ion exchange column with immobilized reagents by hydrolysis.12","PeriodicalId":7814,"journal":{"name":"Analytical Communications","volume":"5 1","pages":"337-339"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84040807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Solvation characteristics of pressurized hot water and its use in chromatography","authors":"T. M. Pawlowski, C. Poole","doi":"10.1039/A809684H","DOIUrl":"https://doi.org/10.1039/A809684H","url":null,"abstract":"The influence of temperature in the range 75–180 °C on the solvation properties of pressurized water is studied by use of chromatography for a varied group of compounds on a porous polymer sorbent PLRP-S 100. The solvation parameter model is used as the basis of a quantitative comparison of the influence of temperature and solvent composition variation on the elution strength and selectivity of the mobile phase. The predominant influence of increasing temperature on the solvation properties of water is to reduce its cohesion and capacity for hydrogen-bond interactions. Even at 180 °C, however, hot water retains sufficient of its room temperature properties to remain a relatively weak eluting solvent in reversed-phase chromatography compared with aqueous mixtures of miscible organic solvents. Changes in selectivity accompanying composition variation for acetonitrile, methanol, and propan-2-ol are quantitatively different from those demonstrated for temperature variation of pressurized water, indicating that for method development the two processes are complementary rather than redundant.","PeriodicalId":7814,"journal":{"name":"Analytical Communications","volume":"40 1","pages":"71-75"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89395893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}