摘要:

Phenol biosensor strips were microfabricated by screen-printing of tyrosinase containing carbon inks. The ability of the enzyme to tolerate the 2-hour firing process (at 110°C) is attributed to its organic phase activity. The resulting strips offer unmediated detection of phenolic compounds down to the 1×10−7M level. Direct assays of untreated drinking-and groundwater samples indicate great promise for field screening of phenolic compounds.

ISSN:0003-2719    

DOI:10.1080/00032719508000333

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A potentially implantable glucose biosensor for continuous monitoring of glucose levels in diabetic patients has been developed. The glucose biosensor is based on an amperometric oxygen electrode and Glucose Oxidase immobilized on carbon powder held in a form of a liquid suspension. The enzyme material can be replaced (the sensor recharged) without sensor disassembly. Glucose diffusion membranes from polycarbonate (PC) and from polytetrafluorethylene (PTFE) coated with silastic are used.

ISSN:0003-2719    

DOI:10.1080/00032719508000334

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Two genetically modified enzymes, galactose dehydrogenase and lactate dehydrogenase carrying polyhistidine tails, were used to develop a simple method for quantitation of transition metals. The samples containing copper, nickel or zinc were initially adsorbed to Chelating Sepharose. Excess of engineered enzyme was added and allowed to bind to the chelated metal ions via their additional histidine tails. The amount of metal ions could be determined by addition of enzyme substrate. The detection limits for copper and zinc were 0.01 μmole and 0.2 μmole, respectively.

ISSN:0003-2719    

DOI:10.1080/00032719508000335

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

An improved hydrogen peroxide based glucose electrode has been used for the determination of glucose in a variety of food samples (soft drinks, fruit juice, honey, syrup, sugar substitute and cake). Both steady state and flow injection measurements were studied and compared with a spectrophotometric method. The biosensor analyses are quick and simple in sample preparation and measurement.

ISSN:0003-2719    

DOI:10.1080/00032719508000336

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A method is proposed for the solvent extraction of cobalt using 1,5-bis(di-2-pyridylmethylene) thiocarbonohydrazide (DPTH) as extractant. The optimum extraction conditions were evaluated from a critical study of the effect of pH. concentration of extractant, shaking time and ionic strength. The maximum volume ratio of the aqueous to organic phase was 30:1 for a single-stage extraction of 99-100 % of the metal ion. The detection limit is 0.9 ng/ml cobalt, and the calibration is linear from 0.9 to 1000 ng/ml. The effect of interferences was studied and no interferences from the elements commonly found in biological materials were observed. The extraction method was applied to the determination of cobalt in some biological materials using inductively coupled plasma atomic emission spectrometry (ICP-AES).

ISSN:0003-2719    

DOI:10.1080/00032719508000337

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Two methods for the determination of pyrithioxine in pharmaceutical formulations by means of oxidative coupling and extractive spectrophotometry are described. Oxidative coupling of pyrithioxine (PYT) with 3-methyl -2- benzothiazolinone hydrazone hydrochloride (MBTH) in the presence of cerium ammonium sulphate (Ce(IV)) forms a coloured product (Method A). The coloured product has maximum absorbance at 635 nm. The second method is based on the formation of an ion-association complex of pyrithioxine with suprachen violet 3B (SV3B) at pH 1.3 which is extracted into chloroform (Method B). The complex has maximum absorbance at 550 nm. The methods obey Beer's law and the precision and accuracy of the methods are checked by U.V. reference method9. These methods have been applied to the determination of pyrithioxine in pharmaceutical formulations.

ISSN:0003-2719    

DOI:10.1080/00032719508000338

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Narcotine reacts with potassium iodate and antimony potassium tartarate to give a yellowish orange colour having maximum absorbance at 430–440 nm. The reaction is specific for narcotine, having 1 ug/10 ml as visual limit of identification and provides a basis for a new spectropho-tometric determination of pure narcotine and in the presence of other drugs. The maximum tolerable limits of these are reported.

ISSN:0003-2719    

DOI:10.1080/00032719508000339

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Ethylmorphine, morphine, codeine, cocaine, sernyl (PCP), LSD, 3-quinuclidinyl benzilate (BZ) provide, together with Cresol Red, ion-associates that are extractable by chloroform. The extracts of the ion-associates prove the absorption maxima in the interval 405 to 415 nm. Maximum extraction of the analytes of the ion-associates is reached after 4 minutes, taking readings of different pH values in 4 intervals of 1.5. This method allows detect of alkaloids and synthetical psychopharmaca row of quantities between 0.45 μg.ml−1and 1.55 μg.ml−1and to determine 1.05 μg.ml−1to the amount 2.99 μg.ml−1of the analytes in the aqueous solutions.

ISSN:0003-2719    

DOI:10.1080/00032719508000340

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This research deals with the quantitative formation of carbon dioxide in electrolytic oxidation reactions. The electrolytic reactions were run with barium peroxide to generate the superoxide anion at the anode. With the organic compounds used in these electrolytic studies we needed to develop a method where we could determine the amount of carbon dioxide liberated from these compounds with the superoxide anion. This method degasses an acidified solution with dry nitrogen, which carries the carbon dioxide to a standard solution of sodium hydroxide. Titration of the sodium hydroxide solution with standardized hydrochloric acid revealed the amount of carbon dioxide formed in the reaction after precipitation of the carbonate ions with barium chloride. Blank runs with the apparatus using anhydrous sodium carbonate produced 99% plus results of recovered carbon dioxide from the sodium carbonate.

ISSN:0003-2719    

DOI:10.1080/00032719508000341

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Nitrite ion can be determined with a high degree of accuracy and sensitivity by differential pulse polarography, based on the catalytic effect of nitrite on the oxidation of Nile blue A in the presence of sodium bromate at acidic media and 25°C. The reaction rate was monitored by measuring the differential pulse polarography peak current of the Nile blue A. Nitrite concentration of 2 - 2000 ng.ml−1can be determined by the fixed time method of 3 min from initiation of the reaction. The limit of detection was 0.4 ng.ml−1. The effects of more than forty ions on nitrite determination were studied. The method was used to determine nitrite concentration in processed river and spring water.

ISSN:0003-2719    

DOI:10.1080/00032719508000342

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor