摘要:

In this study we report the development and experimental evaluation of a miniature Stöber glass-coated enzyme electrode for glucose biosensor applications. The enzyme - glucose oxidase - is chemically immobilized onto the surface of the Stöber glass beads after a silanization procedure. The sensors were fabricated using glass beads of different radii ranging from 20 nm to 100 nm. The overall thickness of the glass coating was about 1.4 μm in all cases. Initial calibration curves of the electrodes show an increase in the response value with decrease in the bead radius. Life-time evaluation tests, however, demonstrate a different behavior of the electrodes. At the end of a 50 day test, the electrode with bead radius of 70 nm remained most stable. The response of this electrode was stable over this period of time and no apparent decrease in its sensitivity was observed. This study suggests that there may be a relation between the immobilized enzyme stability and the porosity of the glass-bead layer. Preliminary tests in undiluted blood plasma suggest that electrodes can be used for glucose measurements in body fluids.

ISSN:0003-2719    

DOI:10.1080/00032719508004027

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

An immunoassay technique based on a high surface area carbon immunoelectrode is described. Dispersed ULTI carbon serves as a carrier for immobilized antibodies and also as an electrode material. ‘Sandwich’ scheme of immunoassay of rabbit IgG (as a model analyte) has been used. Iodine formed as a result of the enzymatic oxidation of iodide by peroxidase-label has been detected amperometrically. Using dispersed carbon material as a solid support for immobilization of immunoagents and as an electrode material improves the efficiency of immuno-interaction and the sensitivity of electrochemical assay due to the high area-to-volume ratio of solid to liquid phases.

ISSN:0003-2719    

DOI:10.1080/00032719508004028

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

An electrochemical procedure for the analysis of L-lactate based on the lactate dehydrogenase/lactate oxidase reaction cycle has been developed and applied in whole blood and wine. The reaction of lactate with lactate oxidase produces pyruvate, which is the substrate, at physiological pH, of the enzyme lactate dehydrogenase. This enzyme, in the presence of NADH, converts pyruvate to lactate consuming H+An automated software controlled differential pHmeter was used for H+detection and the ΔpH measured was correlated to the lactate concentration present in the sample.

ISSN:0003-2719    

DOI:10.1080/00032719508004029

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Fluorescence spectroscopy was applied to the development of a sensitive and simple method for the determination of chlorpromazine HCl and thioridazine-HCl. The method is based upon development of an intense fluorescence using N-bromosuccinimide as the fluorogenic reagent. The produced fluorescence has very characteristic excitation and emission spectra and was stable for at least one hour. The results were reproducible and as little as 5 ng/ml chloropromazine HCl and 1 ng/ml thioridazine-HCl could be determined. The method was applied successfully to the analysis of various commercially available dosage forms. The obtained results were in good agreement with those of the official BP 93 procedures.

ISSN:0003-2719    

DOI:10.1080/00032719508004030

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A simple and sensitive colorimetric method has been developed for the determination of four phenolic drugs, namely, etilefrine hydrochloride, ritodrine hydrochloride, isoxsuprine hydrochloride and salbutamol sulphate. The method is, mainly, based on the nitration of the drug molecule followed by the subsequent formation of meisenheimer complex with a nucleophilic reagent (acetone) in alkaline medium. The experimental conditions leading to optimum chromogen intensity and stability were carefully studied and incorporated in the general procedure. Under the proposed conditions, the method was applicable over the concentration range of 4.8–16 μg ml−1for the four drugs. The suggested method was further applied for the determination of the studied drugs in bulk and pharmaceutical dosage forms. The results of the analysis were found to agree statistically with those obtained with either the official or the referee methods. The procedure is characterized by its simplicity with accuracy and precision.

ISSN:0003-2719    

DOI:10.1080/00032719508004031

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

In this study, simultaneous determination of caffeine and meclizine dihydrochloride in their binary mixture was conducted by two spectrophotometric methods. In the first method, derivative spectrophotometry, the quantification of caffeine and meclizine dihydrochloride was performed by reading the dA/dλ values at 286.2 nm and 243.4 nm respectively in the first derivative spectra of their mixture in methanol. The relative standard deviation of the method was 0.54% for caffeine and 0.67% for meclizine dihydrochloride. In the second, selective precipitation + derivative spectrophotometry, determination of meclizine dihydrochloride was carried out by precipitation with potassium ferricyanide at pH 2 selectively, then measuring the absorbance of its solution in methanol at 420.8 nm, and determination of caffeine was succeeded by reading the dA/dλ values at 260.6 nm in the first derivative spectra of the remaining solution after precipitation. Relative standard deviation of the method was found to be 0.56% for caffeine and 1.85% for meclizine dihydrochloride. These two methods were applied successfully to a sugar-coated tablet containing these drugs.

ISSN:0003-2719    

DOI:10.1080/00032719508004032

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Simple spectroanalytical methods are proposed for the determination of five heterocyclic nitrogenous compounds. The suggested methods depend upon the formation of the ion-pair complexes of the studied compounds with ammonium reineckate followed by colorimetric and atomic absorption measurement of the complexes solutions. The proposed methods were applied to the determination of some pharmaceutical dosage forms containing the studied compounds. Results obtained were in agreement with those obtained by official and compendium methods.

ISSN:0003-2719    

DOI:10.1080/00032719508004033

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The adsorption of carbon monoxide from basic solution (0.1 M LiOH) on a palladium electrode was investigated. It was found that adsorption of CO takes place below the potential -0.25 V (vs. SCE). Surface concentration of the adsorption products, their composition and structure depend on the adsorption potential. The CO adsorption products block hydrogen absorption in palladium but in contrary to acidic solutions don't block the hydrogen desorption process.

ISSN:0003-2719    

DOI:10.1080/00032719508004034

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

An HPLC detector was modified to operate as a low pressure on-line supercritical fluid extraction detector. Spectra of CO2and fluorene are presented of pressures ranging from 85 to 150 atm. Both the intensity and emission wavelength of fluorene were effected by CO2pressure. As pressure increased, the emission intensity also increased and the emission shifted to a shorter wavelength. The intensity of CO2emission decreased by increasing pressure. The emission wavelength of CO2was unaffected by pressure. A detection limit for fluorene was found to be 5 μg per extraction. The minimal detectable mass was 25 μg (± 8% RSD) per extraction.

ISSN:0003-2719    

DOI:10.1080/00032719508004035

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A simple heat driven pump for in-the-field supercritical fluid extraction was constructed and evaluated. The pump pressurized CO2from a standard (54 atm) siphon tube supply cylinder to over 400 atm. Pressurization was achieved and maintained by cyclic heating of a pump chamber containing CO2to 250°C then cooling and refilling the pump chamber with CO2. The pressurized CO2was transferred to a heated reservoir from which the CO2flowed into the extraction cell. Pulse free pressure was maintained in the extraction cell indefinitely at 135 atm with a back pressure regulator. The pressure variation of the solvent delivered to the extraction cell during this period was negligible. The total weight of the system was 5.5 Kg.

ISSN:0003-2719    

DOI:10.1080/00032719508004036

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor