| 1. |
- Kroger, S, et al.
(författare)
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Assessment of glucose oxidase behaviour in alcoholic solutions using disposable electrodes
- 1998
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Ingår i: Analytica Chimica Acta. - : Elsevier Science B.V., Amsterdam.. - 0003-2670 .- 1873-4324. ; 368:3, s. 219-231
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Tidskriftsartikel (refereegranskat)abstract
- Solvent resistant screen-printed three-electrode devices were employed to assess the behaviour of free and immobilised glucose oxidase in water-miscible organic solvent/aqueous buffer mixtures. Three alcoholic solvents were examined, methanol, ethanol and isopropanol. A rhodinised-carbon electrocatalyst was employed to facilitate hydrogen peroxide oxidation at a decreased operating potential. The devices had a linear response range of 1-10 mU GOX and allowed detection of down to 2 x 10(-14) mol GOX. The measurement of 0-1 (v/v) glucose in 30% (v/v) ethanol was achieved in 2 min using these highly storage-stable enzyme electrodes. Such devices are likely to have widespread applications in the diagnostic and on-line monitoring fields where rapid analysis in alcoholic matrices is desirable. (C) 1998 Elsevier Science B.V. All rights reserved.
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| 2. |
- Kroger, S, et al.
(författare)
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Electrochemical assay method for the rapid determination of oxidase enzyme activities
- 1998
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Ingår i: Biotechnology Techniques. - : KLUWER ACADEMIC PUBL. - 0951-208X .- 1573-6784. ; 12:2, s. 123-127
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Tidskriftsartikel (refereegranskat)abstract
- The standard photometric method for the determination of oxidase enzyme activity is compared with an electrochemical approach, involving the use of cheap, disposable screen-printed electrodes. Development and characterisation of the electrochemical device is reported. The electrochemical approach is demonstrated to be advantageous, particularly with regard to speed, ease-of-use, chemicals required and decentralisation of analysis.
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| 3. |
- Kroger, S, et al.
(författare)
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Immunosensor for 2,4-dichlorophenoxyacetic acid in aqueous organic solvent soil extracts
- 1998
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Ingår i: Analytical Chemistry. - : ACS American Chemical Society. - 0003-2700 .- 1520-6882. ; 70:23, s. 5047-5053
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Tidskriftsartikel (refereegranskat)abstract
- The development of a simple electrochemical immunoassay procedure for the field-based quantification of the herbicide 2,4-D in methanolic soil extracts is presented. The sensor utilizes a competitive immunoassay format incorporating an immobilized antigen complex at the surface of a disposable screen-printed working electrode element, The extent of glucose oxidase-labeled antibody binding td the antigen-electrode is determined amperometrically and is related to sample analyte concentration. The performance of the sensor is assessed in buffer, 30% methanol, and methanolic soil extracts. The device is capable of quantifying 2,4-D in all three matrixes at the low ppm level with coefficient of variation values of 6.2-33.6%. The causes of the variation observed in the sensor response indifferent soil matrixes are examined and improvements proposed. The sensor, tested in parallel with a commercial 2,4-D immunoassay test kit, yields comparable quantitative data and detection limits while exhibiting greater assay simplicity.
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| 4. |
- Sarkar, P, et al.
(författare)
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Screen-printed amperometric biosensors for the rapid measurement of L- and D-amino acids
- 1999
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Ingår i: The Analyst. - : Royal Society of Chemistry. - 0003-2654 .- 1364-5528. ; 124:6, s. 865-870
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Tidskriftsartikel (refereegranskat)abstract
- Screen-printed three-electrode amperometric sensors incorporating L- and/or D-amino acid oxidase for the general purpose measurement of L- or D-amino acids is described. The working electrode incorporates rhodinised carbon, to facilitate hydrogen peroxide oxidation at a decreased operating potential, and immobilised enzyme. The devices responded to all 20 common L-amino acids and all of the D-amino acids examined, the exceptions being L- and D-proline. Linear response profiles were observed for L-leucine, L-glycine and L-phenylalanine with limits of detection of 0.47, 0.15 and 0.20 mM respectively. The devices were reproducible and exhibited stability over a 56 d test period. The biosensor compares favourably with a standard photometric amino acid test and was used to monitor milk ageing effects, The assay is cheap, simple to perform and rapid, requiring only buffer-electrolyte and a small sample volume.
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| 5. |
- Sarkar, P, et al.
(författare)
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Screen-printed biosensor for allergens
- 2005
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Ingår i: Journal of chemical technology and biotechnology (1986). - : John Wiley andamp;amp; Sons, Ltd. - 0268-2575 .- 1097-4660. ; 80:12, s. 1389-1394
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Tidskriftsartikel (refereegranskat)abstract
- Allergen levels in indoor environments, leading to many diseases, eg asthma, rhinitis and conjunctivitis, affect a large and increasing fraction of the population. A quite effective and inexpensive method of a rough but very rapid overall assessment of total allergen level in the environment has been developed. The method involved estimation of protein in allergen extracts by screen-printed electrodes using two different techniques. The biosensor comprised a rhodinised carbon working electrode, a silver/silver chloride reference electrode and a carbon counter electrode. In the first method the enzyme protease reacted with allergen protein to release amino acid, which produced hydrogen peroxide in the presence of amino acid oxidase. This was detected amperometrically. The second method used potassium bromide as electrolyte and the electrode was subjected to dual potential. Bromine, released due to electrolysis at higher potential, was consumed by the allergen protein at lower potential. In the first method, a unique technique was used to microencapsulate the enzyme protease and immobilise it on the surface of the electrode by in-situ polymerisation to avoid contact with the amino acid oxidase. A total of seven allergens were tested and the results gave a good correlation with the standard protein measurement method. Environmental specimens from indoors, schools and workplaces can be evaluated for the aeroallergens produced by dust mites, animal hairs, cockroach debris, pollens, etc as a means of determining the exposure risk. (c) 2005 Society of Chemical Industry.
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| 6. |
- Setford, SJ, et al.
(författare)
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Organic phase immunosensors
- 1999
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Ingår i: Analusis. - : E D P SCIENCES. - 0365-4877 .- 1286-482X. ; 27:7, s. 600-609
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Forskningsöversikt (refereegranskat)abstract
- Many analytical methods involving non-polar analytes require solvent extraction prior to measurement, The analysis procedure is greatly simplified if the method is able to function effectively in the more non-polar solvent extract, This consideration, coupled with the increasing need for simple, specific and rapid diagnostic and screening tools, has focused interest in the development of organic-phase immunosensors.
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