摘要:

The concept of biologically modified carbon paste is shown to be very attractive for the design and operation of miniature bioelectrodes. In particular, tissue-containing carbon paste microelectrodes combine the ease of fabrication, with fast response times, high sensitivity and low cost. The very fast response is attributed to the close proximity of the biocatalytic and sensing sites. These features are illustrated using a mixed banana/carbon-paste microelectrode that offers selective and sensitive determination of dopamine. The performance of this microelectrode is further enhanced by using high-speed background subtraction square-wave scanning. The suitability of this electrode for in-vivo and in-vitro studies of brain chemistry is discussed. Other biosensing applications may benefit from such coupling of the technologies of surface modification and miniaturization.

ISSN:0003-2719    

DOI:10.1080/00032718808066346

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A sensor for the determination of inosine was prepared by a combination of the enzyme system (shown below) and an amorphous silicon ISFET (a-ISFET).

ISSN:0003-2719    

DOI:10.1080/00032718808066347

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A method for the determination of mercury(II) ions at trace levels is described. The method is based on the profound inhibitory effect of mercury on the enzyme urease. The activity of the enzyme was determined by the rate of ammonia produced from urea as followed by an ammonia gas sensitive iridium thin metalfilm-oxide-semiconductor (IrTMOS) structure. Two systems were investigated. For the initial urease activity studies, a simple microcell was used. Also, a test plate, containing dry reagent strips with all necessary chemicals was developed, making the analytical procedure very simple to perform. The test volume applied was 2 μl and the sensitivity to standards of mercury(II) ions is at least 0.005 μM (1.0 ng/ml). One sample could be analyzed in less than 8 minutes. Furthermore, the kinetics of sensor response versus enzyme activity is discussed.

ISSN:0003-2719    

DOI:10.1080/00032718808066348

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Glucose was continuously determined by reaction in a packed-bed enzyme reactor containing glucose oxidase and catalase. Oxygen consumption was measured amperometrically with a polarographic Clark electrode. Glucose was sampled through a dialysis probe immersed in the solution to be measured. An extension of the normal range for the enzyme was achieved by modulating the flow rate through the dialysis probe and a linear response was obtained in the range of 1.0-60 mM glucose. The correlation between the glucose transfer and the membrane area of the dialysis probe was also studied. Six different membranes were used, all showing variations in the adhesion of yeast cells.

ISSN:0003-2719    

DOI:10.1080/00032718808066349

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A simple and rapid liquid chromatographic assay method using a fluorescence detector for quantitation of dihydroergotamine in plasma without extraction was developed. After precipitating the protein with acetonitrile, the supernatant liquid was directly injected for analysis. Chromatographic separation was achieved on C18reversed phase column and the mobile phase was the isocratic mixture of methanol, acetonitrile and glycine buffer (0.5:3.5:6.0). With this eluting solvent the drug and its internal standard were well separated from the interference of the plasma sample. The average recovery of dihydroergotamine from 6 replicate samples of different concentrations (5-30 ng/ml) were 92.2 ± 3.37%. The minimum amount of dihydroergotamine detectable by this method was 2 ng/ml of sample.

ISSN:0003-2719    

DOI:10.1080/00032718808066350

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A simple, accurate and rapid method for the quantitative determination of five ranitidine drugs in pharmaceutical formulations (Tablets and Ampoules) is proposed. The supporting electrolyte was acetic acid-sodium acetate buffer solution (pH 5.2). An excellent linear relationship was obtained between the concentration and current with correlation coefficient 0.9996. Good agreement was obtained between the results with the d.c. polarograhic method and those by the manufacturer's method of assay.

ISSN:0003-2719    

DOI:10.1080/00032718808066351

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A new facile and sensitive spectrophotometric procedure for the quantitative determination of adrenaline has been established. The method is based principally on the interaction of the compound with Cu(II)-neocuproine and subsequent measurement of the cuprous neocuproine chelate produced in the reaction at 458 nm. Optimization of the reaction conditions was conducted. Beer's law was obeyed in the concentration range 0.4-2.4 ppm of adrenaline. The method finally developed has been successfully applied for the assay of the drug in some of its pharmaceutical formulations.

ISSN:0003-2719    

DOI:10.1080/00032718808066352

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A radioreceptor assay (RRA) method is described to detect opioid peptides that uses a canine limbic system P2receptor preparation and3H-methionine enkephalin as the displaced ligand. In our laboratory,3H-ME is a useful probe to detect the presence of, and to facilitate the description of, opioid peptides in biological extracts. Those opioid receptor-active peaks are then studied subsequently in greater detail with immunoassay and mass spectrometry methods. A variety of peptide ligands including leucine enkephalin, beta-endorphin, Tyr-D-Ala-Gly-NMe-Phe-Gly-OL (“DAGO”), Tyr-D-Ser-Gly-Phe-Leu-Thr (“delta-receptor peptide”), and several dynorphins (1-7, 1-8, 1-9, 1-10, 1-17, and B) were used to further characterize the molecular specificity of that RRA system.

ISSN:0003-2719    

DOI:10.1080/00032718808066353

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Carbon dioxide has been found to enhance the chemiluminescence of a luminol system. A determination method for carbon dioxide in water was developed by applying this reaction to a continuous flow membrane-separation system. Concentrations of carbon dioxide as low as 0.04 μ g C /mL were determined. Membrane-separation effectively eliminates interferences from Co(II), Cr(III), Fe(III), and other ions which also enhance chemiluminescence. The relative standard deviation for this method was 2.8% (n=5) for 4.0 μ g C /mL and the time required for the analysis of one sample was 3.0 min.

ISSN:0003-2719    

DOI:10.1080/00032718808066354

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Preliminary investigations by a batch method are described for aiming at the flow determination of free chlorine in water with novel chemiluminescence (CL) detection. The CL originates from the reaction of xanthene dyes with free chlorine, Cl2, HOCl, and OCl−. Through the measurements of CL decay curves, fundamental CL characteristics were explored from the analytical point of view. Among xanthene dyes tested, eosin Y. eosin B. pyronin B. and rhodamine 6G were found to be promising CL reagents with such sensitivity and selectivity that free chlorine can be readily determined in tap water. In particular. these CL systems have the special advantage of being insensitive to oxo acids of chlorine and chloramine. Recommended flow systems are proposed.

ISSN:0003-2719    

DOI:10.1080/00032718808066355

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor