RESUMEN
A novel electrochemical sensor is described for the determination of ofloxacin (OFL) in environmental water samples. A laser-modified glassy carbon electrode (LGCE) was structured and characterized by scanning electron microscopy, atomic force microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy. The increase in electrochemical activity is due to a moderate increase in the surface roughness and to the presence of functional groups on the LGCE. Under optimal conditions (viz. a pH value of 5.5, a laser power of 1.8 W and an action time of 40 s), the sensor is capable of detecting OFL by differential pulse voltammetry at a working potential of +0.91 V (versus Ag/AgCl). Response is linear from 0.25 to 200 µM for OFL concentration range, and the detection limit is 75 nM (at S/N = 3). Removal of oxygen from samples is not required. The sensor was successfully applied to the determination of OFL in spiked groundwater, tap water and wastewater samples, with apparent recoveries from 94.0 to 108.0% and a relative standard deviation of less than 4.8%." Graphical abstractSchematic representation of a method for determination of ofloxacin (OFL) by differential pulse voltammetry. It is making use of a laser modified glassy carbon electrode (LGCE), which increases the number of active functional groups and the surface area compared to a conventional GCE.
RESUMEN
A hybrid integration of nanoporous gold with silicon nitride waveguide has been realized for surface-enhanced Raman spectroscopy (SERS) at 633-nm wavelength. The SERS signal is excited through 580-nm-thick T-shape suspended waveguides and collected through an objective lens. Raman spectra for different mesa width at either transverse electric (TE) or transverse magnetic (TM) mode are measured and compared. The localized surface plasmon resonance of the nanoporous gold can result in a waveguide and polarization-dependent SERS enhancement. The presented miniaturized SERS chips can work from visible to near-infrared wavelength and a wide application prospect could be expected.