摘要:

This article focuses on the research activities performed in Argentina in the field of Analytical Chemistry in the last five years. It is organized in four major areas: I) Spectroscopy, II) Mass Spectrometry, III) Chromatography and IV) Electrochemistry. Citations, in general, are limited to journal articles and usually do not include patents, proceedings, reports and dissertations.

ISSN:0003-2719    

DOI:10.1080/00032719908542944

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

An electrocatalytic detection on a potassium hexacyanoferrate (II) modified polypyrrole electrode has been studied. The pyrrole electropolymerization was carried out on a Pt disk of 3 mm diameter, using constant potential chronoamperometry in the presence of the modifier. The electrochemical control of the electropolymerization and modification permit us to know the polymerisation charge, Qp, as well as the number of moles of K4Fe (CN)6incorporated into the polymer at its generation step using Faraday's Law. Finally a determination method for vitamin C (ascorbic acid) using scan and differential pulse voltammetry was developed. This method was applied to determination of vitamin C in several samples, such as tablets and orange drinks, using the standard addition method.

ISSN:0003-2719    

DOI:10.1080/00032719908542945

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The analytical performance of two modified electrodes (a tyrosinase biosensor and a glassy carbon electrode (GCE) covered with poly[Ni-(protoporphyrin IX)dimethyl ester]) in comparison with the bare electrode has been evaluated in a flow injection system using standard solutions of oleuropein and olive oil samples. The tyrosinase biosensor appeared to be an appropriate device for the selective determination of phenols, moreover it can be easily incorporated in an on-line system. This method was used to evaluate the stability of the samples.

ISSN:0003-2719    

DOI:10.1080/00032719908542946

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A carbon paste electrode modified with a new chelating reagent pyruvaldehyde bis(N,N′-dibutyl thiosemicarbazone) (TPSB) for the voltammetric simultaneous determination of lead (II) and copper (II) was described by anodic stripping voltammetry (ASV). The metal ion is accumulated on the surface of the modified electrode by the chelating effect of the modifier in the carbon paste, and then is determined by ASV after the potential reduction at-1.0V. For a 5-min accumulation time, two linear calibration graphs were obtained in the range 2x10−6to 8x10−8M and 1.57x10−7to 1.26x10−9M for lead and copper, respectively. The detection limits are 2x10−9M for lead and 1.57x10−10M for copper for 20 minutes of accumulation time. A chemical and electrochemical renewal allows the use of a single modified electrode in multiple analytical determination over several days. For twenty preconcentration—determination—renewal cycles, the peak current of voltammetry of analyte decreases slightly. Many other ions have no or little effect on the determination. The mechanism of electrode reaction was also discussed.

ISSN:0003-2719    

DOI:10.1080/00032719908542947

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

We describe a spectrophotometric analytical method for the detection of polyphenol oxidase activity in an aqueous solution. The assay is based on the coupling reaction between 4-tert-butyl-o-benzoquinone, generated during the enzyme-catalyzed reaction acting on 4-tert-butylcatechol, and the aromatic amine, 4-amino-N,N-diethylaniline to yield a blue adduct (λmax625 nm). This blue adduct exhibited spectral features different from the parent phenol and from theo-quinone. Polyphenol oxidase activities extracted from potatoes, and sunflower seedlings were assayed. The proposed method presents several advantages over the spectrophotometric measurement of 4-tert-butyl-o-benzoquinone. The duration of the linear period was increased, allowing a better determination of its value. The molar extinction coefficient of the blue adduct was higher than that of the 4-tert-butyl-o-benzoquinone; therefore the limitation i8542948 by the comparatively low ɛ for the 4-tert-butyl-o-benzoquinone is overcome. This is of great importance when considering the inertness of the 4-tert-butyl-o-benzoquinone towards some common coupling agents such as 3-methyl-benzothiazolin-2-one hydrazone.

ISSN:0003-2719    

DOI:10.1080/00032719908542948

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The use of UV spectrophotometry (first-derivative/zero-crossing and zero-order spectra/multivariate calibration) is reported for the analysis of two miotic agents in ophthalmic solutions. The resolution of these mixtures has been accomplished without prior separation or derivatisation by using: 1) first-derivative measurements at two appropriate zero-crossing points: λ1= 222 nm, where the absorption corresponding to excipients is negligible, and λ2= 307 nm, where the contribution of pilocarpine and excipients to the overall absorption is negligible, and 2) partial least squares (PLS-1) regression analysis of zero-order spectral data. Although the components show an important degree of spectral overlap, they have been simultaneously determined with high accuracy, and with no interference from ophthalmic solution excipients.

ISSN:0003-2719    

DOI:10.1080/00032719908542949

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Naproxen reacts with 1-naphthylamine and sodium nitrite to give an orangish red colour having maximum absorbance at 460-480 nm (working wavelength 480 nm). The reaction is selective for naproxen with 0.001 mg/ml as visual limit of quantitation and provides a basis for a new spectrophotometric determination. The reaction obeys Beer's law from 0.01mg to 6.5 mg/10ml of naproxen and the relative standard deviation is 1.5%. The quantitative assessment of tolerable amount of other drugs is also studied.

ISSN:0003-2719    

DOI:10.1080/00032719908542950

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Assay procedures based on UV spectrophotometry and high-performance liquid chromatography (HPLC) have been developed for the determination of meloxicam in tablet formulations. The HPLC method used a reversed-phase C18 column with 0.05M Tris acetic acid buffer - tetrabutylammonium reagent–acetonitrile as eluent, and UV detection at 360nm with isoxicam as the internal standard. The UV method was based on measuring an acidic solution of the drug at 341nm. A comparison was established in terms of linearity, sensitivity, precision, and accuracy. Both methods were simple and rapid. HPLC was more precise and more accurate, the UV technique was slightly faster.

ISSN:0003-2719    

DOI:10.1080/00032719908542951

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Imipramine-HCl reacts with ammonium vanadate in the presence of HCl to give a green colour having maximum absorbance at 400-410 nm. The reaction is selective for imipramine-HCl with 0.001 mg/ml as visual limit of quantitation and provides a basis for a new spectrophotometric determination. The colour reaction obeys Beer's law from 0.001 mg to 0.05 mg/ml of imipramine-HCl and the relative standard deviation is 1.1%. The quantitative assessment of the tolerable amount of other drugs is also studied. The method has been applied to pure drugs as well as to commercial preparations and is precise and reproducible.

ISSN:0003-2719    

DOI:10.1080/00032719908542952

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

This work describes the determination "in natura" of copper ions in alcoholic distilled beverages by anodic stripping voltammetry without previous treatment or addition of supporting electrolyte, using a glassy carbon electrode. The choice of an appropriate stripping voltammetric method minimizes the organic content influence and assures the good reproductivity of the measurements. The reliability of the method was tested comparing the results with the anodic stripping voltammetry, with a hanging mercury drop electrode, and atomic absorption spectrometry giving differences of about 7%. The method allows to determine copper ion in the μg L−1concentration range.

ISSN:0003-2719    

DOI:10.1080/00032719908542953

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor