Voltammetry and amperometric detection of tetracyclines at multi-wall carbon nanotube modified electrodes.
The voltammetric behaviour and amperometric detection of tetracycline (TC) antibiotics at multi-wall carbon nanotube modified glassy carbon electrodes (MWCNT-GCE) are reported. Cyclic voltammograms of TCs showed enhanced oxidation responses at the MWCNT-GCE with respect to the bare GCE, attributable to the increased active electrode surface area. Hydrodynamic voltammograms obtained by flow-injection with amperometric detection at the MWCNT-GCE led us to select a potential value E(det) = +1.20 V. The repeatability of the amperometric responses was much better than that achieved with bare GCE (RSD ranged from 7 to 12%), with RSD values for i (p) of around 3%, thus demonstrating the antifouling capability of MWCNT modified electrodes. An HPLC method with amperometric electrochemical detection (ED) at the MWCNT-GCE was developed for tetracycline, oxytetracycline (OTC), chlortetracycline and doxycycline (DC). A mobile phase consisting of 18:82 acetonitrile/0.05 mol L(-1) phosphate buffer of pH 2.5 was selected. The limits of detection ranged from 0.09 micromol L(-1) for OTC to 0.44 micromol L(-1) for DC. The possibility to carry out multiresidue analysis is demonstrated. The HPLC-ED/MWCNT-GCE method was applied to the analysis of fish farm pool water and underground well water samples spiked with the four TCs at 2.0 x 10(-7) mol L(-1). Solid-phase extraction was accomplished for the preconcentration of the analytes and clean-up of the samples. Recoveries ranged from 87 +/- 6 to 99 +/- 3%. Under preconcentration conditions, limits of detection in the water samples were between 0.50 and 3.10 ng mL(-1).
Department of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid, 28040 Madrid, Spain.
D
D
Vega
L
L
Agüí
A
A
González-Cortés
P
P
Yáñez-Sedeño
J M
JM
Pingarrón
D000900:Anti-Bacterial Agents / Q000032:analysis*; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D002021:Buffers; D002751:Chlortetracycline / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D004318:Doxycycline / Q000032:analysis; D004563:Electrochemistry; D004566:Electrodes; D005504:Food Analysis / Q000379:methods; D006863:Hydrogen-Ion Concentration; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010084:Oxidation-Reduction; D010118:Oxytetracycline / Q000032:analysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013754:Tetracyclines / Q000032:analysis*; D014867:Water / Q000737:chemistry
D000900:Anti-Bacterial Agents; D002021:Buffers; D037742:Nanotubes, Carbon; D013754:Tetracyclines; D014867:Water; D004318:Doxycycline; D002751:Chlortetracycline; D010118:Oxytetracycline