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Biomedical subjects

G J Patriarche

Publications and source records attributed to G J Patriarche.

At least 19 recordsLinked to original sources
PubMed1991

New modified polymeric electrodes selective to local anaesthetic compounds.

New polymeric electrodes responding to the cationic forms of tetracaine (TC), lidocaine (LD), and procaine (PC) were constructed by incorporating their ion-pair complexes (the salts of TC, LD and PC with phosphotungstic acid) into ethylene-vinyl acetate (E/VAC) copolymer. Other ion pairing agents investigated were silicotungstate and tetraphenylborate. The phosphotungstic acid resulted in the best linear and Nernstian response. A 1:1 (v/v) mixture of dioctyl phthalate (DOP) and nitrobenzene (NB) was used as plasticizer. The electrodes exhibited linear response over the concentration ranges 10(-2)-5.6 x 10(-6), 10(-2)-2.5 x 10(-5) and 10(-2)-1.8 x 10(-5) M of TC, LD and PC, respectively. pH did not affect the electrode performances within the ranges 2.7-6.3, 2.6-6.7 and 2.8-7.5 for the three electrodes, respectively. Interferences are negligible for many organic base and alkali metal cations. Cations of similar structure interfere with LD and PC, but not appreciably with TC. Direct potentiometry was used to determine these compounds in pharmaceutical preparations with accurate results.

Electrodes↗
PubMed1989

Adsorptive stripping voltammetry applied to drug analysis: a powerful tool.

A brief review of the principles and instrumentation of adsorptive stripping voltammetry is presented and the advantages of the method are described. As for many highly sensitive techniques applied to the analysis of complex media, severe interferences may occur. Different approaches can be used to circumvent these problems, exemplified by several applications in biological fluids. The application of modified electrodes to enhance selectivity is discussed.

Adsorption↗
PubMed1989

Applications in drug analysis of carbon paste electrodes modified by fatty acids.

The oxidation of promethazine as a model compound has been studied by adsorptive stripping voltammetry at carbon paste electrodes (CPE). A modification of the carbon paste matrix with fatty acids allows greater preconcentration of the molecule at the electrode surface. Several fatty acids of different chain length have been tested. The modification of the CPE with lauric acid has been successfully applied in the quantitative analysis of promethazine in standard serum samples. The influence of several parameters affecting the accumulation step has been investigated such as: pH, ionic strength, interfering ions, paste composition. The detection limit in phosphate buffer at pH 9.0 (tacc = 5 min) has been found to be 1 x 10(-10) M.

Carbon↗
PubMed1988

Electrochemical behaviour of cis-platin at carbon paste and platinum electrodes.

The electrochemical behaviour of a platinum(II) anti-tumour drug (cis-platin) has been investigated at the platinised platinum and carbon paste electrodes using cyclic voltammetry. Measurements performed in neutral aqueous media at the platinised platinum electrode as a function of free chloride ions have enabled the nature of oxidised species to be established and the sensitive determination of the molecule within the range of concentration 1 x 10(-3) - 1 x 10(-5) M to be realised. Use of the carbon paste electrode offers interesting insights into the redox stability of the molecule and allows the hydrolytic degradation of cis-platin to be followed as a function of time.

Journal Article↗
PubMed1987

Redox behaviour of anti-tumor platinum (II) compounds (carboplatin) at solid electrodes.

The electroactivity of a cytostatic complex of platinum (II) possessing no halide ligand (carboplatin) has been studied in aqueous media using platinum and carbon paste electrodes. Cyclic voltammetry has been conducted in order to elucidate the redox behaviour of carboplatin as a function of chloride concentration. Reduction was not observed although oxidation was detected. The nature of the compounds formed during the electro-oxidation was directly related to free chloride ions. At the carbon paste electrode, the reduction of the oxidized species occurred in two steps with the formation of cis-platinum structures and a subsequent electrodeposition of platinum particles. The surface modification step at the carbon paste electrode has demonstrated electrocatalytic properties of the electrode towards platinum (II) complexes possessing halide ligands in their structures. Electrodeposition of platinum ions at a platinum electrode surface as well as a judicious choice of working parameters allows quantitative determinations in the concentration range 3 x 10(-4) - 1 x 10(-5) M.

Journal Article↗
PubMed1986

New trends on modified electrodes: applications to drug analysis.

It is shown that activity in the area of chemically modified electrodes continues at a high level. This topic is increasing in popularity with a large research field on the incorporation of electroactive groups into a variety of conductive films. These developments are also directed towards catalyzing bioselective and biospecific reactions. Significant developments in the field of ion-selective electrodes have occurred and some exciting advances in all areas of these sensors are reported, albeit briefly.

Journal Article↗
PubMed1983

[Not Available].

The analysis of pharmacologically active compounds using electrochemical techniques with modified electrodes is reviewed. Several physical and chemical methods for the immobilization of materials on to electrodes are available, and the resulting surfaces can be examined microscopically . Examples of these procedures and their analytical applications are given.

English Abstract↗