Biomedical subjects

Anastasios Economou

Publications and source records attributed to Anastasios Economou.

3 recordsLinked to original sources

PubMed2004

A study of Nafion-coated bismuth-film electrodes for the determination of trace metals by anodic stripping voltammetry.

This work reports on the fabrication, characterization and applications of Nafion-coated bismuth-film electrodes (NCBFE's) for the determination of trace metals by anodic stripping voltammetry (ASV). A NCBFE was typically prepared by first applying a 5 microl drop of a 1% Nafion solution onto the surface of a glassy-carbon rotating-disk electrode. After evaporation of the solvent, the Bi film was plated on the electrode in situ(i.e. by spiking the sample with 1000 microg l(-1) of Bi(iii) and simultaneous electrolytic deposition of the metal ions and bismuth film on the electrode surface at -1.4 V) or ex-situ(i.e. by electrolytic deposition of the bismuth film in a separate solution containing 1000 microg l(-1) of Bi(iii), followed by the ASV measurement step in the sample solution). Various fabrication and operational parameters were thoroughly investigated and discussed in terms of their effect on the ASV signals. It was found that this voltammetric sensor was suitable for the determination of metals at trace levels by square-wave ASV (SWASV) due to its multi-element detection potential, improved analytical sensitivity, high resistance to surfactants, low cost, ease of fabrication, robustness, speed of analysis and low toxicity (as compared to traditional mercury electrodes). In the presence of 4 mg l(-1) of Triton X-100, the NCBFE afforded a 10-fold peak height enhancement for the Pb peak and a 14-fold enhancement for the Cd peak over a bare BFE while the determination of Zn was feasible only on the NCBFE. The limits of detection (at a signal-to-noise ratio of 3) were 0.1 microg l(-1) for Cd and Pb and 0.4 microg l(-1) for Zn for a deposition time of 10 min. Finally, the electrode was applied to different real samples (tap-water, urine and wine) for the analysis of trace metals with satisfactory results.

Bismuth↗

PubMed2004

Automated sample preparation based on the sequential injection principle. Solid-phase extraction on a molecularly imprinted polymer coupled on-line to high-performance liquid chromatography.

A molecularly imprinted polymer (MIP) prepared using caffeine, as a template, was validated as a selective sorbent for solid-phase extraction (SPE), within an automated on-line sample preparation method. The polymer produced was packed in a polypropylene cartridge, which was incorporated in a flow system prior to the HPLC analytical instrumentation. The principle of sequential injection was utilised for a rapid automated and efficient SPE procedure on the MIP. Samples, buffers, washing and elution solvents were introduced to the extraction cartridge via a peristaltic pump and a multi-position valve, both controlled by appropriate software developed in-house. The method was optimised in terms of flow rates, extraction time and volume. After extraction, the final eluent from the extraction cartridge was directed to the injection loop and was subsequently analysed on HPLC. The overall set-up facilitated unattended operation, operation and improved both mixing fluidics and method development flexibility. This system may be readily built in the laboratory and can be further used as an automated platform for on-line sample preparation.

Automation↗

PubMed2004

Rapid spectrofluorimetric determination of lisinopril in pharmaceutical tablets using sequential injection analysis.

The present work reports for the first time a simple and rapid method for the spectrofluorimetric determination of lisinopril (LSP) in pharmaceutical formulations using sequential injection analysis (SIA). The method is based on reaction of LSP with o-phthalaldehyde (OPA) in the presence of 2-mercaptoethanol (borate buffer medium, pH=10.6). The emission of the derivative is monitored at 455 nm upon excitation at 346 nm. The various chemical and physical conditions that affected the reaction were studied. The calibration curve was linear in the range 0.3-10.0 mg L(-1) LSP, at a sampling rate of 60 injections h(-1). Consumption of OPA reagent was significantly reduced compared with conventional flow injection (FI) systems, because only 50 microL of OPA was consumed per run. The method was found to be adequately precise ( s(r)=2% at 5 mg L(-1) LSP, n=10) and the 3 sigma detection limit was 0.1 mg L(-1). The method was successfully applied to the analysis of two pharmaceutical formulations containing LSP. The results obtained were in good agreement with those obtained by use of high-performance liquid chromatography (HPLC), because the mean relative error, e(r), was <1.8%.

Calibration↗