Biomedical subjects

L Angnes

Publications and source records attributed to L Angnes.

4 recordsLinked to original sources

PubMed2001

Amperometric determination of dipyrone in pharmaceutical formulations with a flow cell containing gold electrodes from recordable compact discs.

A simple, rapid, and precise amperometric method for quantification of dipyrone in pharmaceutical formulations is presented. The proposed method permits determinations in the 10(-7) mol L(-1) of the analyte and enables 90 determinations h(-1), employing only 100 microL of sample per determination. This method is based on the direct quantification of dipyrone in many pharmaceutical products, avoiding cumbersome processes such as previous separations, solvent extraction, or sample filtration. This new procedure was applied to commercial pharmaceutical tablets, and the results obtained were in excellent agreement with the ones obtained by the classical iodometric method.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2000

Gold electrodes from recordable CDs

Gold electrodes are widely used in electrochemistry and electroanalytical chemistry. The notable performance when used in stripping analysis of many ionic species and the extraordinary affinity of thio compounds for its surface make these electrodes very suitable for many applications. This paper reports a simple and novel way to construct gold electrodes (CDtrodes) using recordable CDs as the gold source. The nanometer thickness of the gold layer of recordable disks (50-100 nm) favors the construction of band nanoelectrodes with areas as small as 10(-6) cm2. The plane surface can be easily used for the construction of conventional-sized gold electrodes for batch or flow injection analysis or even to obtain electrodes as large as 100 cm2. The low price of commercial recordable CDs allows a "one way use". The evaluation and applicability of these electrodes in the form of nanoelectrodes, in batch and associated with flow cells, are illustrated in this paper.

Journal Article↗

PubMed2000

Gold electrodes from recordable CDs for mercury quantification by flow injection analysis.

The development of a new methodology for the construction of very efficient flow cells for mercury detection by potentiometric stripping analysis, employing the thin gold layer of recordable CDs as working electrode is reported. This new source of electrodes (CDtrodes) show very attractive performance, similar to that obtained with commercial gold electrodes, with superior versatility. The low cost of this new source of "gold electrodes" allows a frequent replacement of the electrode, avoiding cumbersome clean-up treatments. Various experimental parameters have been optimized to yield low detection limits (0.25 ng/mL of mercury for 5 min deposition at 0.3 V) and good precision (standard deviation of 1.9% was obtained for 15 repetitive measurements using 10 ng/mL of mercury). Standard curves were found to be linear over the range of 0.5-100 microg L(-1) of mercury. The flow cells developed were used for the quantification of mercury in oceanic and tap water.

Journal Article↗

PubMed2000

Modified microelectrodes and multivariate calibration for flow injection amperometric simultaneous determination of ascorbic acid, dopamine, epinephrine and dipyrone.

Flow injection amperometric quantification of ascorbic acid (AA), dopamine (DA), epinephrine (EP) and dipyrone (DI) in mixtures (in the microgram g-1 range) was successfully performed by using an array of microelectrodes with units modified by the electrodeposition of different noble metals, together with multivariate calibration analysis. The four groups of microelectrodes utilized included a pure gold electrode and electrodes modified by electrodeposition of platinum, palladium or a mixture of platinum + palladium. The array of microelectrodes was inserted in a flow cell and the amperometric data acquisition was performed with a four-channel potentiostat. The analysis of the resulting signals was carried out by a multivariate calibration method, using a group of 16 standard mixtures selected by a two-level factorial design. The analysis of synthetic samples and pharmaceutical compounds containing AA and DI led to very similar values to those obtained by the classical iodimetric analysis. The average absolute errors (in microgram g-1) calculated for each analyte were 0.3, 0.2, 0.4 and 0.4 for AA, DA, EP and DI, respectively.

Ascorbic Acid↗