摘要:

The design of efficient oxygen measuring devices has important environmental, clinical and process control applications. Several methods are available for oxygen quantitation, but those based on the dynamic quenching of luminescence of inorganic compounds have several advantages. In this work the oxygen-quenching luminescence characteristics of a newly synthesized ruthenium (II) compound immobilized on an optical fiber was investigated using Stern-Volmer kinetic analysis. Results obtained show that the luminescence intensity of the newly synthesized compound exhibits a second order dependence on oxygen concentration from 0–100 %. The oxygen sensing characteristics of this new compound are comparable to other conventional oxygen sensing compounds.

ISSN:0003-2719    

DOI:10.1080/00032719708001742

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Small molecules, peptides, and proteins can be imprinted using mixtures of organic silanes. Molecular imprints may serve as artificial receptors,i.e., biosensor sensing elements for detection of chemical and biological toxins, drugs, and environmental hazards. One method for detection of imprint-bound molecules is fluorescence. Molecular imprints to N-acetyltryptophanamide (NATA) and fluorescein were prepared, and their respective binding constants determined using steady-state fluorescence spectroscopy. Stern-Volmer fluorescence quenching plots of imprint-bound molecules using potassium iodide (KI) and acrylamide indicate bound molecules are shielded from the solvent environment. Scatchard plot analysis revealed two binding affinities,i.e., aKd= 0.13 and 2.5 μM for NATA binding to NATA imprints. Interestingly, NATA exhibited higher affinity,i.e., Kd= 1.3 and 35 nM, for the fluorescein imprint. These data support the usefulness of fluorescence techniques in molecular imprint-based detection technology.

ISSN:0003-2719    

DOI:10.1080/00032719708001743

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A simple and sensitive method for the determination of steroids using micellar liquid chromatography is described. The steroids, including hydroxycorticosterone. corticosterone, northisterone, testosterone, mexdroprogesterone acetate and progesterone, were separated by reversed-phase using a micelles mobile phase following UV detection at 245 nm. The parameters affecting retention of the test solutes such as the concentration of sodium dodecyl sulfate (SDS) and n-butanol-1 in the mobile phase were investigated. It was found that the retention of the solutes was dependent on the composition of mobile phase. The linear calibration plots range from 0.1 to 10 μg ml−1in mobile phase containing 5.0 × 10−2mol l−1SDS/9 % n-butanol-1 at pH 6.0, and the detection limit in order of 0.1 μg ml−1was obtained. The proposed method was used for the determination of steroids in urine using direct injection of samples without previous treatment.

ISSN:0003-2719    

DOI:10.1080/00032719708001744

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The application of capillary electrophoresis (CE) to the separation and determination of the two active ingredients, magnolol and honokiol, inMagnolia officinalisand its processed product was described. Optimum separation was achieved with a fused-silica capillary tube(60.5cm × 75μm I.D.) and a Na2B4O7-NaH2PO4buffer(20 mmol/L) at pH=9.0 containing 20% of methanol. The applied voltage was 20 kV and the capillary thermostating temperature was kept constant at 25 deg;C.

ISSN:0003-2719    

DOI:10.1080/00032719708001745

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Two methods, namely first derivative and classical least squares methods are selected and applied for comparative purposes to analyze uv-spectra of the methanolic solutions of the cited components in synthetic binary mixtures and in a number of antibacterial pharmaceutical preparations, viz. three tablets and two syrups produced by Egyptian companies. The former technique is based on measuring the absorbances at zero-crossing wavelengths, 288 and 240 nm for the two drugs, respectively. Calibration curves are rectilinear in the range 4 –20 μg/ml of both components. The latter method is based on a pure standard full-spectra treatment ranged from 350 to 200 nm at 2 nm intervals to compute the concentration of unknowns. A statistical analysis of the results is reported.

ISSN:0003-2719    

DOI:10.1080/00032719708001746

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A flow-injection method is proposed for the determination of chlorpromazine and other N-substituted phenothiazines. The procedure is based on the oxidation of analyte with lead dioxide entrapped into polymeric material in a packed-bed reactor. The oxidation of the drug yields soluble Pb2-, which is monitored by means of the lead ion selective electrode in the wall-jet configuration. The calibration graph is linear over the range of 0.01 – 2 μg ml−1of chlorpromazine with relative standard deviation of 1.4% and sample throughput 20 h−1. The developed method was applied to the determination of chlorpromazine in pharmaceutical preparations.

ISSN:0003-2719    

DOI:10.1080/00032719708001747

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A flow injection (FI) spectrophotometric method is proposed for the determination of promazine hydrochloride. The method is based on the coupled redox - complexation reactions which proceed in the promazine-iron(III) and 1,10-phenantroline system. A linear calibration graph was obtained between 2–12 ppm of promazine hydrochloride with a sampling rate of 163 samples h−1. The proposed method was applied to the determination of promazine in pharmaceuticals.

ISSN:0003-2719    

DOI:10.1080/00032719708001748

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Utilisation of azine dyes for the development of four simple spectrophotometric methods are described for the determination of Ranitidine hydrochloride (RTH) in pure form and pharmaceutical formulations. Method A is a direct one, which involves the formation of an ion-association complex (λmax:600 nm) between the drug molecule and wool fast blue BL. The other three methods, indirect ones, involve the addition of excess oxidant (chloramine-T, for method B; potassium permanganate, for method C, N-bromosuccinimide, for method D) of known concentration in acid medium to RTH and the determination of the unreacted oxidant by measurement of the decrease in absorbance of gallocyanine (GC for method B), cresyl fast violet acetate (CFVA for method C) or celestine blue (CB for method D) at a suitable maximum wavelength (λmax:540 nm for methods B&D and λmax: 555 nm for method C). The validities of the methods are tested against the spectrophotometric reference method and all are in good agreement.

ISSN:0003-2719    

DOI:10.1080/00032719708001749

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A comparative cyclic voltammetric study of the Bunte salts adsorption and oxidation of the electrode reaction products on gold and platinum electrodes was performed. These were irreversibly adsorbed on both metals, and were oxidized to disulfides (on gold in basic solution) and in the anodic range of platinum electrode potentials to form water soluble sulfates. Also Bunte salts were oxidized directly from the bulk of solution. Platinum was found to show stronger (than gold) electrocatalytic properties to adsorb and oxidize the electrode reaction products of Bunte salts

ISSN:0003-2719    

DOI:10.1080/00032719708001750

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A Partial Least Squares (PLS) calibration method was applied to the simultaneous determination of iprodione, procymidone and chlorothalonil in mixtures, by uv-vis absorption spectrophotometry and by high performance liquid chromatography (HPLC). Signals and first-derivative (1D) signals were used to optimize the calibration matrices by the PLS-1 method. Quantitative results are presented for synthetic mixtures and for extracts from soil and groundwater samples. Significant improvements were achieved by using the PLS-1 method built with first-derivative chromatograms, in the determination of iprodione, procymidone and chlorothalonil in environmental samples.

ISSN:0003-2719    

DOI:10.1080/00032719708001751

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor