摘要:

A radically new approach for the discriminative determination of various neurotoxins has been developed. This novel biosensor combines a highly sensitive acetylcholinesterase (AChE) biosensor with immobilized organophosphate hydrolase (OPH). The value of the new concept was demonstrated by the discrimination between carbamate and organophosphorus pesticides. It was shown that the response of traditional AChE-based biosensor to mixed samples containing paraoxon and carbofuran was not simply additive, and the measured concentrations of these pesticides were very different from their real concentrations. This combined OPH/AChE system was able to improve the accuracy of the AChE-based biosensor and to uniquely distinguish paraoxon in mixed solutions containing carbofuran. The presented approach promises a new perspective for “real world” analyses and opens a new area of discriminative determination of various species in multicomponent solutions.

ISSN:0003-2719    

DOI:10.1080/00032719708001757

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Flow injection determinations of acetate were carried out using immobilized acetate kinase, pyruvate kinase and lactic dehydrogenase with an amperometric method. Two acetate kinases fromE. coliandB. stearothermophiluswere tested. It was found that the immobilized acetate kinase fromB. stearothermophiluswas more stable than that fromE. coli., but it is much more expensive and less available. Acetate kinase coupling at pH 7.4 using CPG aminopropyl and glutaraldehyde seems to be superior to other immobilization methods. A high immobilization yield can be obtained by immobilization of the three enzymes separately giving high conversions of all the three. Plots of current versus concentration show a useful operating range from 0.3 to 2 mM acetate with a linear response. The detection limit was 0.2 mM at a flow rate of 0.3 ml/min with 200 μl injections. The method is therefore well suited for monitoring of the level of acetate in fermentations with acetate as the carbon source.

ISSN:0003-2719    

DOI:10.1080/00032719708001758

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A high performance liquid chromatographic procedure is presented for the determination of nabumetone in pharmaceutical tablets and in plasma. An aliquot of the sample is dissolved in 50% acetonitrile (ACN) containing 4-methoxyacetophenone as an internal standard and chromatographed on a Supelcosil LC-8 (5μ) (150 mm × 4.6 mm i.d.) column. The mobile phase was a mixture of acetonitrile (500 mL), triethylamine (1.5 mL) and glacial acetic acid (8 mL) diluted to 1000 mL, with distilled deionized water. The detection was carried at 270 nm. The method was tested for linearity, recovery and specificity.

ISSN:0003-2719    

DOI:10.1080/00032719708001759

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A method for the fluorimetric determination of fluoxetine in continuous and discontinuous systems is reported. The method is based on the hydrolysis of fluoxetine in acid medium. The fluorescent product has a spectrum with excitation and emission maxima at 253 and 306 nm, respectively. The method was applied to the determination of fluoxetine in pharmaceutical products.

ISSN:0003-2719    

DOI:10.1080/00032719708001760

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A simple, sensitive, accurate and rapid spectrophotometric method for the determination of some anthelmintics that are used in veterinary medication is described, based on the formation of an ion pair complex with bromocresol purple (BCP) and bromocresol green (BCG). Drugs analyzed are piperazine hexahydrate, tetramisole hydrochloride and metronidazole. The drugs were determined either in pure powdered forms or in pharmaceutical formulations using the standard addition technique. The sensitivity, precision and accuracy of the method was discussed and the results compared with the official method of British Pharmacopoeia (B.P. 1993).

ISSN:0003-2719    

DOI:10.1080/00032719708001761

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The determination of bromazepam by spectrophotometry and atomic absorption on the basis of the extraction in methyl isobutyl ketone of the ionic-pair bromazepam-Fe(II) cationic chelate and perchlorate is discussed. Differential spectrophotometry must be used for measuring low levels of the diazepine. Both techniques were applied for determining bromazepam in pharmaceuticals.

ISSN:0003-2719    

DOI:10.1080/00032719708001762

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Two approaches to sorption-photometric determination of 1-naphthol in waters with application of polyurethane foams are offered. The first approach was based on sorption of a coloured 1-naphthol azoderivative, which was formed by the reaction with 4-nitrophenyldiazonium tetrafluoroborate (NFD). In the second variant, 1-naphthol is first sorbed by a polyurethane foam, and it is then transformed into a coloured azoderivative by sorbent treatment of a NFD solution. A coloured 1-naphthol azoderivative was determined immediately in the polyurethane foam using diffuse reflectance spectroscopy. Calibration graphs are linear in the interval of concentrations of 0.01 - 1 μg/ml. The analytical results indicated that a selective and sensitive analytical procedure could be easily applied to determination of 1-naphthol concentration in waters.

ISSN:0003-2719    

DOI:10.1080/00032719708001763

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

An analytical procedure based on the reaction of nitroso-R salt with reduced iron(II) is developed for the analysis of ascorbic acid. The absorbance of the resulting green colored complex is measured at 705 nm. Beer's law is obeyed over the range 0.2–3.0 μg ml−1ascorbic acid with a molar absorptivity of 4.5 × 104l mol−1cm−1. The substances commonly found with vitamin C formulations are tolerated. Some of the marketed products of ascorbic acid were analyzed by the proposed method with satisfactory results.

ISSN:0003-2719    

DOI:10.1080/00032719708001764

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The coordination of the anticancer drug mithramycin to Tb(III), Fe(III) and Cu(II) was studied in aqueous solution using absorption measurements. The stability constants were calculated from equilibrium competition experiments by means of the SQUAD program. For both first ions, the competitor was oxalic acid and for the latter the competitor was the Cu(II) ions. Cu(II) at pH 7.5, Fe(III) at pH 3.5 and Tb(III) at pH 5.5 formed respectively 1:2, 1:3 and 1:4 metal-to-ligand species.

ISSN:0003-2719    

DOI:10.1080/00032719708001765

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A very simple spectrophotometric method using measurements at zero-crossing wavelength is described for resolving ternary mixtures of the food colorants Erythrosine (E-127), Amaranth (E-123) and Tartrazine (E-102). Calibration graphs are linear up to 14 mg/L of Erythrosine and 28 mg/L for Tartrazine and Amaranth. RSD of 0.80, 0.85 and 1.84% were obtained for nine standards of 8 mg/L of Erythrosine, 8 mg/L of Tartrazine and 8 mg/L of Amaranth, respectively. Detection limits of 0.052, 0.934 and 0.123 mg/L were obtained for Erythrosine, Tartrazine and Amaranth, respectively. This method was satisfactorily used for determining synthetic mixtures of these colorants in different ratios and it was successfully applied to a commercial product containing the three dyes; no separation step is required. The results were compared with those obtained by liquid chromatography and very similar values were found by both methods.

ISSN:0003-2719    

DOI:10.1080/00032719708001766

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor