title: Thermodynamic analysis of the thermal stability of sulphonamides in milk using liquid chromatography tandem mass spectrometry detection.
abstract: The present study investigates the kinetics of the degradation of eight sulphonamides in skimmed milk when heated at 60, 70, 80, 90 and 100°C using an LC-MS/MS methodology. To determine the thermal stability of these compounds, the first-order kinetic model was applied and the activation energies, half-lives and degradation percentages were calculated. Application of kinetic equations to the different heat treatments used in dairy processing indicates that sulphonamides are very stable during pasteurisation (63°C; 30 min and 72°C; 15s) as well as UHT sterilisation (140°C; 4s). In contrast, the calculations performed with the kinetic model estimated losses in concentrations between 6.5% (sulfadimethoxine) and 85.1% (sulfamethazine) for the sterilisation at 120°C for 20 min. The existence of thermodynamic compensation was also tested for sulphonamide degradation. Results show that enthalpy and entropy values displayed a good linear relationship, and thermodynamically we can establish that the thermal degradation of sulphonamides in skimmed milk exhibits enthalpy-entropy compensation.
authors.affiliation: Centro Superior de Investigación en Salud Pública, Avenida de Catalunya 21, 46020 Valencia, Spain. roca_marmar@gva.es
authors.forename: M
authors.initials: M
authors.lastname: Roca
authors.forename: R L
authors.initials: RL
authors.lastname: Althaus
authors.forename: M P
authors.initials: MP
authors.lastname: Molina
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry*; D002417:Cattle; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004355:Drug Stability; D005511:Food Handling; D006358:Hot Temperature; D008892:Milk / Q000737:chemistry*; D013449:Sulfonamides / Q000737:chemistry*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D013816:Thermodynamics
chemical_list: D000900:Anti-Bacterial Agents; D013449:Sulfonamides