摘要:

Two new carbon film electrodes have been prepared from the low pressure pyrolysis of aromatic anhydrides onto quartz substrates. The anhydrides employed are safer and more volatile than those previously used for preparing carbon film electrodes. The voltammetric response of the film electrodes both in millimolar dopamine and in background electrolyte was studied. The differential pulse voltammetry response with a mixture of dopamine, homovanillic acid and ascorbic acid was studied. Also, the application of the electrode as an optically transparent carbon electrode was examined. The film electrodes had lower background current than glassy carbon, but the reversibility with dopamine was not ideal. These two new films appear to have utility similar to previously studied films, with the advantage of rapid and safe production.

ISSN:0003-2719    

DOI:10.1080/00032719308017482

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Benzo(a)pyrene (BaP) which presents native fluorescence in solution has been determined in waters by synchronous solid-phase spectrofluorimetry. The relative fluorescence intensity of BaP fixed in Sephadex G-25 gel is measured after being packed in an 1-mm silica cell. Spectral characteristics of BaP-gel system are described. The applicable concentration range was 0.52–3.45 μg.L−1with a relative standard deviation of 1.2% and detection limit of 0.07 μg.L−1. The method was applied to the analysis of waters with different provenances.

ISSN:0003-2719    

DOI:10.1080/00032719308017483

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A method is proposed for the simultaneous determination of nickel and manganese by first-derivative spectrophotometry based on their reactions with 2-(2-pyridylmethyleneamino)phenol (PMAP) Schiff base. The method allows the determination of Ni and Mn in the concentration range 0.3–3.0 μg ml−1in mixtures with their ten-fold concentration ratio. The method has been applied for Ni and Mn determination in bronzes. To optimize the experimental conditions for spectrophotometric determination of Mn with PMAP stability constants at different pH values have been determined. A critical evaluation of the proposed method was performed by statistical analysis of the experimental data.

ISSN:0003-2719    

DOI:10.1080/00032719308017484

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The utilization of an alternating current plasma as an atomization source for atomic absorption spectrometry is described. The analytical performance of this technique has been characterized for the determination of 11 elements. The detection limits (3[sgrave]) were found to be comparable to those determined with existing plasma sources. The accuracy of the method has also been assessed by comparison with flame and graphite furnace atomic absorption spectrometric methods.

ISSN:0003-2719    

DOI:10.1080/00032719308017485

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

An indirect and alternative method for the determination of sulfate ion has been established by spectrophotometry. The procedure is based on the formation of copper(II) monoazido species, in water/acetone medium, in which a discoloration effect of system is caused by sulfate presence. In the recommended conditions, sulfate ions can be determined in the concentration range from 40 to 5000 mg/l (ppm), at 375 nm, in natural samples of waters. The best experimental conditions were determined analysing the different factors involved. Studies about the formation equilibria of the CuN3+and CuSO4species were realized in water and their respective stability constants (β1= 225 M−1and 7.15 M−1) were determined by spectrophotometry at 25.0° C and ionic strength 1.0 M (NaClO4). Equilibrium investigations were also made in presence of acetone. Additional studies on the ternary system Cu(II)/N3−/SO42-) indicated some evidences of mixed complexes.

ISSN:0003-2719    

DOI:10.1080/00032719308017486

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A problem arises when determining the decision and detection limits in a series of results where the variance of the error distribution of the analytical signals around their expectation is not a constant when applying a method proposed by Hubaux and Vos6. In this paper an approach is proposed to overcome this difficulty, that involves the use of a transform method to convert heteroscedastic data to homoscedastic data so that the limit of detection can be obtained by projection of the confidence band about the linear regression. This approach is applied to the case of a gravimetric determination of sulphate ion in the 1 – 5 mgL−1SO42-range. The results obtained from this approach are compared from others obtained previously.

ISSN:0003-2719    

DOI:10.1080/00032719308017487

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A high-performance liquid chromatographic technique for the separation of the optical isomers of salsolinol is described. The simple and rapid method allows the direct resolution of the enantiomers without derivatization. A complete separation (baseline resolution) of (R)-(+)-salsolinol and (S)-(-)-salsolinol could be achieved on a Chiral=Si 100 ß-cyclodextrin column using water mixed with 10% methanol (v/v) and 0.05% trifluoroacetic acid (v/v) as mobile phase. Analyses carried out at a flow rate of 1.0 ml/min were accomplished in less than 12 minutes.

ISSN:0003-2719    

DOI:10.1080/00032719308017488

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A simple post column reaction detection system for fluoride is presented using the decolorization of the zirconyl xylenol orange complex. A 3[sgrave] detection limit of 0.05 μg F−mL−1was achieved with a linear calibration function up to 10 μg F−mL−1. The methodology is suitable for the determination of F−in potable water and some interferences studies were conducted with common cations namely Ca, Mg, Al and Fe(III).

ISSN:0003-2719    

DOI:10.1080/00032719308017489

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

ISSN:0003-2719    

DOI:10.1080/00032719308017490

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

ISSN:0003-2719    

DOI:10.1080/00032719308017491

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor