摘要:

Electrical communication between the flavin adenine dinucleotide redox centers of glucose oxidase and a conventional electrode has been achieved using two electron transfer relay systems based on siloxane-ethylene oxide copolymers containing covalently attached ferrocene moieties. The results from stationary potential experiments show that carbon paste electrodes modified with these redox polymers and glucose oxidase respond rapidly to addition of glucose, with larger steady-state response currents than those measured in previous studies of glucose sensors based on ferrocene-modified siloxane polymers. The results also indicate that the mediating ability of the polymers is dependent upon the length of the ethylene oxide side chain onto which the ferrocene molecules are attached.

ISSN:0003-2719    

DOI:10.1080/00032719308016791

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Urine samples of patients with Graves′ and Hashimoto′s diseases were dialysed and subjected to a sensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) for anti-thyroglobulin IgG. Anti-thyroglobulin IgG in urine was reacted simultaneously with 2,4-dinitrophenylated thyroglobulin and thyroglobulin-β-D-galactosidase conjugate. The immune complex formed consisting of the three components was trapped onto polystyrene balls coated with (anti-2,4-dinitrophenyl group) IgG, eluted with ϵN-2,4-dinitrophenyl-L-lysine and transferred onto polystyrene balls coated with (anti-human IgG γ-chain) IgG. β-D-Galactosidase activity bound to the last polystyrene balls was assayed by fluorometry. Anti-thyroglobulin IgG was detected in most of the patients. The detection of anti-thyroglobulin IgG in urine by the immune complex transfer enzyme immunoassay was suggested to be useful as a diagnostic aid for autoimmune thyroid diseases.

ISSN:0003-2719    

DOI:10.1080/00032719308016792

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Classical cross-linking technology has been found to be of very limited use in identifying solubilized receptors. A new assay based on the use of heparin-Sepharose was developed here for detecting receptors of fibroblast growth factors (FGFs) in detergent-soluble fractions. This new cross-linking assay is based on the heparin-binding properties of FGF. To this end, solubilized FGF receptors were cross-linked to radiolabelled acidic FGF on heparin-Sepharose. Standardization of the method was carried out by using: 1) crude CHAPS-soluble extracts from chinese hamster ovary cells which express human FGF receptor cDNA (FGFR-2); 2) CHAPS-soluble fractions purified by affinity chromatography from bovine retina. This approach might be a valuable tool for detecting receptors of all heparin-binding growth factors.

ISSN:0003-2719    

DOI:10.1080/00032719308016793

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The ion-selective electrode based on decalino-14-crown-4 was prepared and its Li+-selectivity against other alkali metal and alkaline earth metal ions was examined. The poly(vinyl chloride)-matrix membrane ion-selective electrode containing decalino-14-crown-4 as an ion selective ionophore and bis(butyl pentyl)adipate as a membrane solvent exhibited high Li+selectivity of at least 1000 times against all other alkali metal and alkaline earth metal ions. The ion selectivity factor (logkLi,Napot) for Li+/Na+was -3.3, which indicates that this electrode is one of the most selective for Li+/Na+. The electrode showed a linear Nernstian response slope ranging from 1 × 10−6to 1 M of Li+.

ISSN:0003-2719    

DOI:10.1080/00032719308016794

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Coated wire ion-selective electrodes (CWISEs) for the Hyamine 1622 cation (Hy) based on dibenzo-18-crown-6 (DB18C6) and dibenzo-24-crown-8 (DB24C8) are developed. Both electrode systems exhibit stable near Nernstian response over the range 10−3–10−6mole 1−1Hyamine 1622 cation with a slope in the range of 56–59 mv/decade of concentration. The working pH range is 3–9 and the response time varies from 30 to 50 s. The selectivity toward Hyamine 1622 cation is reasonably high relative to many common inorganic cations and organic cations not having surfactant properties. The electrode was suitable for determining the critical micelle concentration and as end-point detector in the potentiometric titration of the cationic surfactants.

ISSN:0003-2719    

DOI:10.1080/00032719308016795

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A spectrophotometric method was developed for the determination of diamino acids (ornithine and lysine) based on their reaction with [Fe(CN)5NO]2-to produce N-heterocyclic amino acids (proline and pipecolic acid). The cyclic amino acids were measured spectrophotometrically based on the well-known Simon-Awe method.

ISSN:0003-2719    

DOI:10.1080/00032719308016796

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Modifications to the 4-aminoantipyrine-potassium ferricyanide procedure for the colorimetric determination of phenols have lead to the development of 3 micro-methods. These were introduced to reduce the sample volume while maintaining the reproducibility of the assay. For that purpose, we have also investigated the possibility of combining some of the reagents. When applied to the evaluation of the arylesterase-like activity of albumin on α-naphtyl acetate via the dosage of α-naphtol, we found an excellent inter-assay reproducibility without compromising our initial goals of accelerating the procedure and reducing the sample volume.

ISSN:0003-2719    

DOI:10.1080/00032719308016797

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The reaction of tobramycin with o-phthaldialdehyde (OPA) in the presence of 2-mercaptoethanol was studied kinetically by using stopped-flow mixing methodology. New data on the kinetics of this reaction were exploited to develop a simple, fast method for tobramycin determination. The linear range (0.05–30.0 μg mL−1), detection limit (0.03 μg mL−1), precision (&RSD 1.92) and selectivity of the proposed kinetic method are quite acceptable. The method was satisfactorily applied to the analysis of pharmaceutical preparations with no pretreatment.

ISSN:0003-2719    

DOI:10.1080/00032719308016798

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The electrochemical reduction of 1-[(2-hydroxyethyl)chloro-methyl]-2-methyl-5-nitro-1H-imidazole (ornidazole) was studied by normal pulse polarography and reverse pulse polarography. In aqueous solution with no surfactant, ornidazole gives rise to one wave (I) or two waves (I and II) depending on pH. The electrode reactions corresponding to these waves were characterized, and appropriate reaction mechanisms are hypothesized. In basic solutions containing DMF or sodium lauryl sulphate, wave I splits into two or three. When splitting is complete, the electrode reaction corresponding to the first daughter wave, I′, is the simple, reversible formation of the anion radical. This circumstance, and the analogous behaviour of metronidazole and tinidazole, was used to determine the formal potential of the nitroimidazole/anion radical system for ornidazole, metronidazole and tinidazole in aqueous media; the results agreed remarkably well with previously reported values obtained by pulse radiolysis. Optimal conditions for the analytical determination of ornidazole by differential pulse polarography were established.

ISSN:0003-2719    

DOI:10.1080/00032719308016799

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A method is described for the flame atomic absorption spectrometry (AAS) determination of vanadium, down to microgram level, in food samples and petroleum crudes. The procedure is based on the synergistic extraction of the V(V)-5,5′-methylene-disalicylohydroxamic acid (MEDSHA) complex with a 0.5 M tributyl phosphate (TBP) solution in isobutyl methyl ketone (IBMK). The method is highly selective and has a detection limit of 0.019 μg.ml−1(Vorg./Vsq.= 0.2) and of 0.006 μg.ml−1(Vorg./Vsq.= 0.05), with a relative standard deviation (RSD) not exceeding 1.5% at a level of 2 μg.ml−1and 3% at a level of 0.4 μg.ml−1.

ISSN:0003-2719    

DOI:10.1080/00032719308016800

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor