摘要:

Genetic algorithms (GA's) are search algorithms that imitate nature with their Darwinian survival of the fittest approach. They are well suited for searching among a large number of possibilities for solutions because they exploit knowledge contained in a population of initial solutions to generate new and potentially better solutions. GA's have several advantages over conventional search techniques. First, GA's consider many points in the search space simultaneously. Because GA's utilize parallelism in which a large number of candidate solutions are simultaneously searched, more of the response surface is probed, so there is a reduced chance of convergence to a local minimum. Second, genetic algorithms make no assumption about the geometry of the response surface. Hence, discontinuities or singularities in the response surface, which rule out the use of derivative or simplex based methods, will not pose a problem for GA's. Third, the computational environment offered by a GA can be readily adjusted to match a particular application. Thus, GA's can be tailored for individual problems. Consequently, GA's can be used to solve a variety of data analysis problems in chemistry including curve fitting, parameter estimation, function optimization, calibration, classification, and wavelength and feature selection.

ISSN:0003-2719    

DOI:10.1080/00032719908542831

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A novel amperometric immunosensor based on graphite paste (graphite powder and paraffin oil) has been constructed. The graphite paste is impregnated with mouse monoclonal anti-(+)-3,3′,5-triiodo-L-thyronine (anti-T3). The immunosensor can be reliably used for L-T3assay in thyroid and in drugs, using chronoamperometric technique, at ppb-ppt concentration levels. The potential used for L-T3assay was 650 mV vs Ag/AgCl. The surface of the immunosensor can be regenerated by simply polishing, obtaining fresh immunocomposite ready to be used in a new assay.

ISSN:0003-2719    

DOI:10.1080/00032719908542832

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Iron(III)-tetrasulfonatophthalocyanine(FeTSPc) has been used as a mimetic enzyme in the determination of hydrogen peroxide with thiamine hydrochloride as a fluorogenic substrate. The determinations were carried out in both acidic and basic environments, with different limits of detection and linear ranges. In acidic condition, the linear calibration graph was obtained from 5.0x10−8mol/L to 8.0x10−6mol/L, with a detection limit of 2.1x10−8mol/L H2O2when Na2HPO4-citric buffer solution (pH 2.8) was used as the reaction medium. It was also found that using one of the three polybasic carboxylic acids such as citric acid, tartaric acid and malonic acid as the catalytic reaction medium can lead to particularly sensitive systems, permitting a detection limit as low as 3.5x10−9mol/L H2O2; whereas in basic reaction medium (Na2CO3-NaHCO3buffer solution, pH = 10.0), the linear range of the calibration graph was from 5.0x10−8mol/L to 2.0x10−6mol/L H2O2with a detection limit of 1.4x10−8mol/L. The applicability of the method to the determination of glucose in human serum was demonstrated by investigating the recovery of the known glucose added to human serum.

ISSN:0003-2719    

DOI:10.1080/00032719908542833

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A simple, rapid and sensitive luminescence spectrometry is described for the determination of some β- lactamic antibiotics in pure form and in pharmaceutical formulations. The proposed method is based on the fact that the redox reaction between cerium(IV) and β-lactamic antibiotics in an acidic medium to form Ce(III), which can luminesce, and sodium has great enhancement for the luminescence intensity of Ce(III). The method permits the determination of 8.0x10−6−2.0x10−3mg/ml, 1.0x10−5−2.0x10−3mg/ml, 2.0x10−5−2.5x10−3mg/ml, and 2.0x10−5−3.0x10−3mg/ml for cepharadine, cefalexin, 6-aminopenicillanic acid (6-APA) and cefazolin respectively. Their detection limits (S/N=3) were 2.0x10−6mg/ml, 7.0x10−6mg/ml, 6.0x10−6mg/ml, and 8.0x10−6mg/ml, respectively.

ISSN:0003-2719    

DOI:10.1080/00032719908542834

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The aim of this study was to assess the suitability of automated dialysis, using a commercial system, for the analysis of sulphonamides in porcine tissue. The system involves automated dialysis, followed by trace enrichment of the dialysate prior to HPLC determination. The procedure was applied to the analysis of nine sulphonamide drug residues using reversed phase HPLC as the method of determination. Muscle samples were blended in saline, centrifuged and the supernatant was filtered before dialysis for an optimised time of 11 min. The resulting dialysate was concentrated on a reversed phase trace enrichment cartridge prior to HPLC analysis with UV detection at 280 nm. The developed method was evaluated by carrying out intra- and inter-assays on fortified porcine muscle. Mean recoveries, evaluated from the inter-assay study, were 80% or higher for the nine sulphonamides studied and the limit of determination for the method was 40 ng g−1.

ISSN:0003-2719    

DOI:10.1080/00032719908542835

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The ratio spectra derivative spectrophotometry was applied for the simultaneous determination of chlordiazepoxide (CH) with clidinium bromide (CL), pipenzolate bromide (PI) or amitriptyline hydrochloride (A) in binary mixtures. The analytical signals were measured at 243.1 and 214.8 nm in the CH-CL mixture, 271.4 and 256.7 nm in the CH - PI mixture, and 264.9 and 218.0 nm in the CH-A mixture for CH and its co-existing compounds, respectively, in the first derivative mode in methanol. Calibration graphs were established for 2.0 - 38.0 μml−1CH and 4.0 - 20.0 μgml−CL in CH - CL mixture, for 2.0 - 38.0 μgml−1CH and 4.0 - 32.0 μgml−1PI in CH - PI mixture, and for 2.0 - 28.0 μgml−1CH and 4.0-36.0 μgml−1A in CH - A mixture. The method was successfully applied to the pharmaceutical formulations containing the above-mentioned drug combinations without any interference by the excipients. Vierordt's method was also developed for a comparison method.

ISSN:0003-2719    

DOI:10.1080/00032719908542836

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The underivatized enantiomers of carbuterol, chemically known as [5-[2-[(1, 1-dimethylethyl)amino]-1-hydroxyethyl]-2hydroxyphenyl]urea, an isoprenaline like oral β2-adrenoceptor agonist widely used as bronchodilator, have been separated in chiral RP-HPLC isocratic system employing a conventional octadecylsilica packed column and chiral, helically self-assembled, neutral, coordinatively unsaturated chelate(-)(M)(λ, Λ)-[4,4′-(1S)-methyl-(2R)-propylethane-diyldiimino)bis(pent-3-en-2-onato)nickel(II) as the chiral selector in the mobile phase comprising acetonitrile-sodium acetate solution. The changes in observed enantioselectivity and resolution of carbuterol stereoisomers caused by organic modifier concentration or chiral selector adsorption were investigated. The formation of hydrogen bonded supramolecules by involving three molecules of the helically self-assembled chiral selector and a single molecule of individual enantiomer of carbuterol have been suggested. Hybridized orientation of interacting molecules in the supramolecular selectand-selector system was exhibited on results of extended analyses of developed chiral recognition model. Considering collected chromatographic and molecular modelling data it has been postulated that process of supramolecular association of the carbuterol enantiomers prevailing in the volume phase of employed RP-HPLC mode. An inverted elution order of(R-)and(S-)enantiomers of analyte have been registered in the presented studies, in contrast to previously reported retention of other sympathomimetic phenylethanolamines (e.g.noradrenaline) in the proposed chiral RP-HPLC system. The presence of a planar ureidoyl moiety in the phenylene ring of carbuterol molecule significantly enhances the stability of supramolecules formed with chiral selectors leading to improved separation of both enantiomers of this drug.

ISSN:0003-2719    

DOI:10.1080/00032719908542837

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Enantiomeric resolution of 4-substituted-pyrrolidin-2-ones were investigated on cellulose chiral stationary phase. The separations were made using normal phase methodology with a mobile phase ofn-hexane-alcohol (methanol, ethanol, 1-propanol or 2-propanol) in various proportions, and a silica-based cellulose tris-benzoate (Chiralcel OJ). The mobile phase was optimized to achieve the best resolution. Effects of variation of alcohol concentration, nature of aliphatic alcohols in the mobile phase were studied. The effects of substitution were analysed. Baseline separation was easily obtained in many cases. The maximum resolution factor obtained was near 7.50.

ISSN:0003-2719    

DOI:10.1080/00032719908542838

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A resin (I) containing imidazolylazo functional group has been used for the separation and preconcentration of palladium(II) and silver(I) from other metal ions in synthetic mixture, ores, alloys and medicinal samples. No interference could be observed from alkali and alkaline earth metal. Palladium(II) is quantitatively separated from ores and platinum wire without interferences.

ISSN:0003-2719    

DOI:10.1080/00032719908542839

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Determination of formaldehyde at sub-ppm level as impurity in acetals using HPLC-DAD is described. Automated on-line precolumn derivatization reaction with 2,4 dinitrophenylhydrazine has been used. Breakdown rates of some industrial scale used acetals (Methylal, Ethylal) to formaldehyde by hydrolysis in aqueous media, according to pH, are described.

ISSN:0003-2719    

DOI:10.1080/00032719908542840

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor