摘要:

A recycling bienzyme electrode for determination of nanomolar ferrocene concentration was developed. The electrode consists of a laccase – glucose dehydrogenase bienzyme membrane coupled with an oxygen electrode. Laccase catalyzes the oxidation of ferrocene with oxygen. Oxidized ferrocene is an electron acceptor for the reaction of glucose oxidation catalyzed by glucose dehydrogenase. The cyclic process of oxidation/reduction of ferrocene gives substrate recycling. The detection is achieved by measuring the decrease in oxygen concentration. In this system the detection limit for ferroceneacetic acid was 0.2 nM.

ISSN:0003-2719    

DOI:10.1080/00032719508006013

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A plasticised PVC Ion-Selective membrane electrode responsive for glafenine cation has been developed. It is based on the use of the ion-associate species, formed by glafenine cation and tetraphenylborate counterion. The basic electrode performance characteristics are evaluated according to IUPAC recommendations. It exhibited a linear response for 1 x 10−21x 10−4M of glafenine solutions with a cationic Nernstian slope over the pH range 1–3.5. Common organic and inorganic cations showed negligible interference. Direct potentiometric determination of 9.8 X 10−5- 9.8 x 10−3M aqueous glafenine hydrochloride using this membrane electrode system showed an average recovery of 99.3% with a mean standard deviation of 1.5%. This electrode system was successfully used for monitoring the titration of glafenine with sodium tetraphenyl borate and for determining glafenine in some pharmaceutical formulations.

ISSN:0003-2719    

DOI:10.1080/00032719508006014

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A relatively rapid and direct method was developed to determine the concentration of amphotericin B in plasma or whole blood. The characteristic maximum emission fluorescence peak observed for amphotericin B at 488nm, after its excitation at 358nm, was used as the basis for its quantitation. Amphotericin B was extracted and plasma or whole blood proteins were precipitated initially with 50% methanol. Residual plasma proteins were precipitated with 5% trichloroacetic acid to reduce their fluorimetric interference to a minimum. Concentrations in the range 0.1 to 4.0μM could be quantitated relatively rapidly by this method. The method was applied successfully to the determination of amphotericin B in its pharmaceutical dosage form in spiked human plasma or whole blood and in the plasma of a patient treated with amphotericin B.

ISSN:0003-2719    

DOI:10.1080/00032719508006015

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A simple, precise and rapid high performance thin layer chromatographic method is developed using chloroform: methanol (9:1) as mobile phase for simultaneous determination of Theophylline and Etofylline in pharmaceutical dosages. Paracetamol was used as an internal standard. The method is linear in the concentration range of 20 – 80 ng for Theophylline and 60–240 ng for Etofylline.

ISSN:0003-2719    

DOI:10.1080/00032719508006016

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

IR- and1H-NMR-spectra of 6 new 2-(alkoxy- and alkoxy-hydroxystyryl)quinolines with antibacterial activity were tested and it was proved that these compounds containtrans-configuration of substituents to ethylene double bond.

ISSN:0003-2719    

DOI:10.1080/00032719508006017

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Dozens of β-blockers are commercially available. The more frequently used in the treatment of glaucoma are as follows: timolol, levobunolol and betaxolol. The analytical methods used for its determination are not always adequate and easy to execute. The objective of this research is to study and to standardize a fast, precise, accurate, sensitive and efficient analytical method for determination of β-blockers in pharmaceutical preparations. The method that accomplished all these requirements was HPLC. A Merck LiChrospher® 100 RP-18 (5 μm) in LiChroCART® (125–4) column, a rotative valve injector (20 μL loop), ambient temperature, a mobile phase consisting of methanol-phosphate buffer pH 3.0 (50:50 v/v and 60:40 v/v) and UV detection makes possible the quantitative determination of timolol, levobunolol and betaxolol contained in ophthalmic solutions.

ISSN:0003-2719    

DOI:10.1080/00032719508006018

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A high performance liquid chromatographic method for the simultaneous determination of metronidazole and diloxanide furoate in single and combined dosage form has been developed. Each drug acted as internal standard for the other. Both of the drugs eluted from the cyclobond column (β-cyclodextrin stationary phase) without retardation effects, using methanol-0.05 M NaH2PO4(pH 7) in ratio 35:65, flow rate 1 ml min−1and detection at 254 nm. Metronidazole and diloxanide furoate gave rectilinear calibration graphs in the ranges 1–10 μg and 1–5 μg respectively.

ISSN:0003-2719    

DOI:10.1080/00032719508006019

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A new spectrophotometric multicomponent analysis method, for resolving a ternary mixture of sulphaquinoxaline (SQX), sulphamethazine (SMT) and pyrimethamine (PMT) on the basis of the simultaneous use of the first derivative of ratio spectra and measurements of zero-crossing wavelengths is described. The procedure does not require any separation step. The optima conditions were established and the method was tested in synthetic mixtures (for SQX:SMT:PMT ratios from 1:1:4 to 1:4:1 and to 4:1:1). Finally, the method is applied for the quantification of the three compounds in a commercial product and the found results are compared with those ones obtained by PLS-2 and HPLC.

ISSN:0003-2719    

DOI:10.1080/00032719508006020

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A simple, quick and sensitive spectrophotometric method based on the combination of norfloxacin and p-benzoquinone at room temperature, apparently by charge-transfer (n → π) mechanism, to yield a 1:1 complex with analytically useful maximum absorption at 495 nm, is described. The estimated molar absorptivity, ε, and the stability constant, K, are 0.44 × 104L mol−1cm−1and 1.06 × 106L mol−1respectively. The role of solvent, p-benzoquinone concentration, pH and presence of water have been investigated. Under the optimized conditions, Beer's Law was obeyed over the concentration range 7.5 – 40 μg/ml of norfloxacin. The concentration range of best accuracy deduced from Ringbom plot was 15–40 μ/ml norfloxacin. When the proposed method was applied to the analysis of commercial tablets (Noroxin®), labeled to contain 400 mg of drug per tablet, the mean percentage found was 100.57 ± 1.58 (n = 9). The precision and accuracy of the method proposed have been compared statistically with the official (U.S.P.) high performance-liquid chromatographic procedure using the F-ratio and Student-tests.

ISSN:0003-2719    

DOI:10.1080/00032719508006021

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A method for determination of tellurium(IV) or tellurium(VI) is described that involves hydrogen telluride generation by reduction with sodium tetrahydro-borate(III), evolution of hydride with HCl solution, transport into a flow-cell placed in a UV-visible molecular absorption spectrophotometer and measurement of gas at 190 nm. Hydride generation and determination procedures are optimized, based on height and area of absorbance versus time profile of hydrogen telluride generated. Using the best experimental conditions found the calibration curve is linear from 5 to 100 μg/ml of tellurium, 1.1 μg/ml of tellurium(IV) or 3.1 μg/ml of tellurium(VI) can be detected, and relative standard deviation ranges from 4 to 7%. The method is applied to the analysis of additives for synthetic rubber making.

ISSN:0003-2719    

DOI:10.1080/00032719508006022

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor