The adsorption and decomposition of carbon monoxide on Ni(100) and the oxidation of the surface carbide by oxygen

The interaction of carbon monoxide with Ni(100) has been studied by ellipsometry and Auger electron spectroscopy. Bombardment by electrons of a relatively high energy (2500 eV) leads to the disproportionation of the adsorbed CO (2 COad → Cad + CO2g ). The rate of oxidation of this surface carbide is , where hc is the carbon 272 eV Auger peak height, n=0.5 and the apparent activation energy Eact =13.3 kcal/mole. This relation is valid at 200–400°C and at oxygen pressures of 5 × 10−9−8 × 10−7 Torr

Comparison of three analytical methods for the determination of quinolones in pig muscle samples

This work presents a comparison between three analytical methods developed for the simultaneous determination of eight quinolones regulated by the European Union (marbofloxacin, ciprofloxacin, danofloxacin, enrofloxacin, difloxacin, sarafloxacin, oxolinic acid and flumequine) in pig muscle, using liquid chromatography with fluorescence detection (LC-FD), liquid chromatography-mass spectrometry (LC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The procedures involve an extraction of the quinolones from the tissues, a step for clean-up and preconcentration of the analytes by solid-phase extraction and a subsequent liquid chromatographic analysis. The limits of detection of the methods ranged from 0.1 to 2.1 ng g−1 using LC-FD, from 0.3 to 1.8 using LC-MS and from 0.2 to 0.3 using LC-MS/MS, while inter- and intra-day variability was under 15 % in all cases. Most of those data are notably lower than the maximum residue limits established by the European Union for quinolones in pig tissues. The methods have been applied for the determination of quinolones in six different commercial pig muscle samples purchased in different supermarkets located in the city of Granada (south-east Spain)