摘要:

A new biospecific technique for organophosphate assay is described. The designed biosensor contains a ferromagnetic core passivated by an epoxide cover in a high-frequency electrical field. Complexing agent molecule with an 8-hydroxy-quinoline region is covalently bound to the cover and serves for strong fixation of aluminum hydroxide. This composition “Magnosorb” binds with the enzyme butyrylcholinesterase. Such a biosensor has high sensitivity to inhibition by organophosphate pesticides (up to 20–50 ng per ml). Various environment and food compounds can be tested without laborious preliminaries. However, the sensor's ability for inhibition is gradually decreased when the full component is stored, whereas esterase activity is more stable. This phenomenon is called “Functional Disadequacy”, and can be corrected with the help of a “Binary Sensor” technique, in which the sensor is made up of two parts (carrier “Magnosorb” and fresh dissolved enzyme) just before use. The proposed method can be used in broad inspection monitoring of an “Alarm Signal”.

ISSN:0003-2719    

DOI:10.1080/00032719608001457

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Tyrosinase-modified carbon paste electrodes were prepared using lyophilised powder of the enzyme purchased from different companies. The selectivity of these electrodes for nine phenolic compounds, including six substituted catechols, has been studied. The signals obtained for catechol were always higher than those found for other phenolic compounds. Cyclic voltammetry and flow injection measurements indicated that the response of the tyrosinase-modified carbon paste electrodes was limited by the rate of the enzymatic oxidation of catechols. Different approaches of paste electrode preparation have been studied and compared. Direct mixing of enzyme into the graphite powder doped with the osmium based mediator, resulted in the highest sensitivity for the studied substrates. However, substrate selectivity was found to be dependent on the source of enzyme used for electrode preparation.

ISSN:0003-2719    

DOI:10.1080/00032719608001458

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The use of a series piezoelectric crystal (SPC) device for the preparation of biosensors has been investigated. These biosensors are fabricated by mounting the immobilized urease layer or the jack bean tissue slices on the probe surfaces of the SPC ammonia sensor. The urease sensor exhibits favourable frequency response to 1 x 10−5-3x10−3M urea with a response time of ca.3 min. Dynamic range, reproducibility, response time and selectivity of the sensors are discussed. Results show the SPC is an attractive alternative internal sensing element to develop biosensing devices. The urease sensor has been used successfully for the determination of urea in serum samples; the results are comparable to those from a spectrophotometric method.

ISSN:0003-2719    

DOI:10.1080/00032719608001459

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A glucose monitoring system consisting of a pair of amperometric sensors: a glucose biosensor based on oxygen electrode and an oxygen sensor, two miniature potentiostats, an instrumentation amplifier and a data logger has been developed. The glucose sensor has linear response to the glucose concentration invitroat 37°C up to 26 mM (480 mg/dL) in the phosphate buffer solution (pH 7.4), and linear range up to 21 mM (380 mg/dL) in undiluted bovine plasma. The system was evaluatedin vivowith the sensors subcutaneously implanted in healthy mongrel dogs. During the implantation the system output was continuously recorded. The results of short-term subcutaneous implantation of the integrated system demonstrated good agreement between the glucose concentration measured by the biosensor and that obtained using standard glucose determination methods. The delay-time between the tissue glucose level (measured by the biosensor) and the blood glucose level (obtained by standard methodology) was 3 to 10 minutes. During the chronic implantation the biosensor was refilledin vivo. Rejuvenation of the sensor response after refilling was observed demonstrating the potential of such sensors for long-term implantation.

ISSN:0003-2719    

DOI:10.1080/00032719608001460

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A molecularly imprinted polymer selective for sialic acid was prepared using two functional monomers,p-vinylbenzeneboronic acid and N, N, N-trimethylaminoethyl methacrylate chloride in 2-hydroxyethyl methacrylate/ethyleneglycol dimethacrylate based copolymers, and specific binding of the target compound sialic acid was achieved in aqueous solution.

ISSN:0003-2719    

DOI:10.1080/00032719608001461

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A Sequential Injection (SI) system was used to analyze the ethanol concentration in fermentation broth. The method is based on the use of immobilized NAD+dependent alcohol dehydrogenase. A non linear standard curve for ethanol (range 0.25–100 mM) was used to determine the concentration in fermentation broth and the results correlated well with HPLC measurements. The assay time was 140 s, 0.5 μmol of cofactor was used for each determination, and the relative standard deviation was less than 6% when analyzing fermentation samples. The assay system is very stable and makes it possible to reduce the cofactor consumption while keeping the system set up simple.

ISSN:0003-2719    

DOI:10.1080/00032719608001462

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A fast procedure for lysine analysis in food was developed by coupling in sequence a microwave protein hydrolysis technique with a lysine enzyme electrode.

ISSN:0003-2719    

DOI:10.1080/00032719608001463

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A bioluminescent fiber optic sensor for the analysis of L-lactate is described. It is based on a reaction sequence catalyzed by three different enzymes: luciferase fromV. harveyi, NAD(P) H: FMN oxidoreductase fromV. fischeriand lactate dehydrogenase from rabbit muscle covalently immobilized on polyamide membranes. Two kinds of sensing layer were studied, one consisting of only one membrane on which the enzymes were randomly coimmobilized, the other being a compartmentalized system obtained by stacking a luciferase/oxidoreductase membrane on a lactate dehydrogenase membrane. After optimization, the performances of the biosensor in terms of sensitivity, detection limit and dynamic linear range of measurements were strongly improved by compartmentalization of the sensing layer compared with those obtained using the coimmobilized system. A fivefold increase in biosensor sensitivity was obtained and the detection limit was 0.2 μM lactate.

ISSN:0003-2719    

DOI:10.1080/00032719608001464

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A high performance liquid chromatographic procedure has been developed for the assay of isradipine in bulk form and tablet and capsule pharmaceutical preparations. The separation is achieved within 20 min on an octadecylsilane column at ambient temperature with a mobile phase of 60:40 v/v methanol - water, a flow rate of 1 mL/min, and detection at 325 nm. Degradation studies showed no peak interference between isradipine and degradation products. It was also determined that the excipients in the commercial tablet and capsule preparations did not interfere with the assay. The method was linear in the range 10–60 μg/mL with accuracy and precision in the 0.40 - 1.53% range.

ISSN:0003-2719    

DOI:10.1080/00032719608001465

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This method is based on the catalytic effect of Mo(VI) on the redox reaction between ethyl orange and hydrazine sulfate in sulphuric acid medium at 100°C, and in 0.03 mol/L H2SO4- 0.30 mol/L NH3-H2O supporting electrolyte. Ethyl orange exhibits a sensitive polarographic wave at -0.52 Vvs.SCE and change of ethyl orange concentration is traced by a polarographic detection technique. The detection limit and the linear range of Mo(VI) are 3.54 ng/mL and 20 to 300 ng/mL respectively. This new catalytic method has been applied to the determination of molybdenum in food, with satisfactory results.

ISSN:0003-2719    

DOI:10.1080/00032719608001466

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor