摘要:

Laccase-containing sol-gels were synthesized by hydrolysis and condensation-polymerization of tetramethylorthosilicates. Two types of laccase containing sol-gel based optical biosensors were designed and tested. The first type is based on 2–8 mm thick monolith sol-gel blocks. It was observed that laccase-containing sol-gel blocks accumulate high molecular weight products of oxidation of the laccase substrate - 2,6-dimethoxyphenol. This leads to at least ten fold increase of optical bioassay sensitivity in comparison with the homogeneous phase. The response time of such biosensors is 3–24 hours. The second type of biosensor is based on laccase-containing 0.3 mm diameter solgel particles in a flow cell and includes an optical fiber measuring system. This sensor is characterized by a fast response time in comparison with the first type. The latter biosensor also possesses a homogeneous phase assay sensitivity and yields a linear calibration curve.

ISSN:0003-2719    

DOI:10.1080/00032719608000797

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

An integrated thermal biosensor array was designed and fabricated for the simultaneous determination of glucose, urea and penicillin. The sensor contains six thin-film thermistors which were fabricated on quartz chip by micromachining and semiconductor technology. This sensor allows the determination of three different analytes nearly simultaneously by serially partitioning a single microchannel into three distinct detection regions. Each of the regions contained one immobilized enzyme matrix and a pair of thermistors for differential measurement of temperature changes in association with the enzyme reactions. Using this device, glucose, urea and penicillin-G at different concentrations were determined in the mixed samples. Linear ranges of 1 to at least 25 mM urea and penicillin, and up to 20 mM glucose were obtained using a sample volume of 20 μL.

ISSN:0003-2719    

DOI:10.1080/00032719608000798

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A new type of porous, composite material is synthesized and used for direct wiring of active enzymes. The material is comprised of a dispersion of graphite powder and redox enzymes incorporated in hybrid, pendant ferrocenyl-, alkylamine- and methyl- modified silicate backbone. Each species in this integrated construction accomplishes a specialized task; the percolating graphite powder provides conductivity, the silicate provides highly crosslinked, rigid backbone, which is used to cage the redox enzymes; ferrocene functional groups are responsible for the signal transduction from the active center of the enzyme to the percolating graphite; amine groups were incorporated for their high affinity to excess negative charges on the surface of glucose oxidase; and finally, the combination of methyl- and amine- groups is advantageous to maintain a control over the thickness of the wetted electroactive section of the electrode. Amperometric sensing of glucose demonstrates the application of this new material.

ISSN:0003-2719    

DOI:10.1080/00032719608000799

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This paper presents a general method of enzyme immobilization at the surface of ion selective membranes. Covalent binding of enzymes directly on the electrode surface is a very effective method that results in stable enzymatic membranes. As an example the construction of enzymatic sensors for urea determination based on ammonium and hydrogen carbonate ion selective electrodes is presented. The optimum working conditions for these biosensors were found. Bioelectrodes based on an ammonium sensor show very good analytical parameters: dynamic stability - over 2 months without decrease of sensitivity, response time - shorter then 20 s. high sensitivity, determination range from 0.3 to 70 mM. In the contrast to the ammonium ion based biosensors, those constructed on the basis of anion selective electrodes have worse analytical parameters. It is mainly due to poor selectivity and instability of an applied ion selective electrode. In spite of this, both types of urea biosensors were used for measurements in the differential potentiometry mode. The application of such system increased the sensitivity of urea determination.

ISSN:0003-2719    

DOI:10.1080/00032719608000800

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A simple and sensitive method for the determination of vanadium in tissues was established by using atomic absorption spectrophotometry with graphite furnace atomisation. The proposed method includes formation of a chelate-complex by reacting vanadium with pyrrolidine dithiocarbamate (PDCA), extracting the chelate with xylene and measurement of the extract using atomic absorption spectrometry. The recoveries of added vanadium in various rat tissues were 96.7 and 109.3%, within 8.6% of the coefficient variation. The sensitivity of this method is 10 – 50 times higher than previous methods, the detection limit is 0.01 μg/g.

ISSN:0003-2719    

DOI:10.1080/00032719608000801

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In this study, two new spectrophotometric methods were used for the simultaneous determination of cilazapril and hydrochlorothiazide in their binary mixture. In the first method, derivative spectrophotometry, dA/dδ values were measured at 242.8 nm and 282.8 nm for cilazapril and hydrochlorothiazide, respectively, in the first derivative spectra of their combination. The relative standard deviation of the method was found to be 0.77% for cilazapril and 0.24% for hydrochlorothiazide. In the second, the absorbancy ratio method, the quantification of cilazapril and hydrochlorothiazide was performed by using the absorbances read at 210.4 nm. 250.2 nm and 270.6 nm in the zero-order spectra of their mixture; relative standard deviations of the method were found to be 1.26 % and 0.81 % for cilazapril and hydrochlorothiazide, respectively. These two methods have been successfully applied to a tablet containing these drugs.

ISSN:0003-2719    

DOI:10.1080/00032719608000802

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Capillary zone electrophoresis with amperometric detection was employed for the determination of lincomycin and lincomycin B in bulk drug and pharmaceutical formulations. The electrode used was a 300μm diameter Cu disk electrode operated in a wall-jet configuration. With an applied potential of +675mV (vs Ag/AgCl) and 80cm capillary(i.d. 25μm) at 26kV in the electrophoretic medium of 0.lOmol/L NaOH, lincomycin and lincomycin B could be completely separated within 15 minutes with resolution of 2.3. The response was linear over the concentration of 10.0–150.0μg/mL with a correlation coefficient of 0.9998, and the detection limit of 1.0μg/mL for lincomycin. The results of analysis were 98.2–99.3% of lincomycin label claims, and compared favourably with those obtained by the official method. The method is simple, rapid and precise for routine analysis of underivatized lincomycin and lincomycim B in bulk drug and pharmaceutical formulations.

ISSN:0003-2719    

DOI:10.1080/00032719608000803

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Hollow cathode glow discharge atomic emission spectrometry has been applied to the determination of silicon coupled with a novel gaseous hydride generation technique, involving drying of an aqueous solution of silicate (sample) and mixing with powdered LiAlH4. Sample introduction into the glow discharge chamber was performed via a pinhole at the center of the cathode which was connected to the hydride generator. The detection limit for silicon was 6μg at 288.1 nm and 30 μg at 251.6 nm.

ISSN:0003-2719    

DOI:10.1080/00032719608000804

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A simple, real time one dimensional imaging system for reaction heat-induced optical beam deflection is reported. The neutralization reaction between HCl and NaOH was used as a model reaction. The neutralization reaction occurs in a glass tube with internal diameter of 2.3 mm, used as a reaction cell, and imaged well.

ISSN:0003-2719    

DOI:10.1080/00032719608000805

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The effect that resolution has on the calculated signal-to-noise ratio (SNR) of an emission line measured in the visible by a high resolution Fourier Transform Spectrometer is discussed. The resolution varies from a physically resolved profile (0.02 cm−1) to a shape dominated by the instrumental function (2 cm−1). The effects that incorporating inaccurate signal-to-noise ratios has on figures of merit for a FT-UV/VIS system is discussed.

ISSN:0003-2719    

DOI:10.1080/00032719608000806

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor