Thiamphenicol Drug Residue [KLH]

The binary solid liquid phase equilibrium for 4-(methylsulfonyl)benzaldehyde in methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, acetone, acetonitrile, toluene, and acetic acid were studied experimentally within the temperatures range from (283.15 to 318.15) K under 101.3 kPa by using a static equilibrium method. With the increase in temperature, the solubility of 4-(methylsulfonyl)benzaldehyde in these solvents increased. The solubility values from high to low obeyed the following order in different solvents: acetone > acetonitrile > acetic acid > methanol > ethanol > toluene > 1-butanol > 1-propanol > 2-propanol. The modified Apelblat equation, lambda h equation, Wilson model, and nonrandom two liquid model were employed to correlate the experimental solubility of 4-(methylsulfonyl)benzaldehyde in the nine solvents. The calculated solubility with the modified Apelblat equation provided better agreement than those with the other three models. Generally, the regressed results by the four thermodynamic models could be acceptable for 4-(methylsulfonyl)benzaldehyde in the studied solvents. The acquired solubility data could provide a theoretical basis for the purification of crude 4-(methylsulfonyl)benzaldehyde.

Heat stability of amphenicols and the relationship between structural degradation and antimicrobial activity after heating has not been well investigated. Florfenicol (FF), thiamphenicol (TAP), and chloramphenicol (CAP) were heated at 100 degrees C in water, salt water, soybean sauce and chicken meat for up to 2 h. Degradation and antimicrobial activity of the compounds was evaluated using capillary electrophoresis (CE) with UV-DAD spectrometry, minimum inhibitory concentration (MIC) assay, and gas chromatography with electron impact ionization mass spectrometry (GC-EI-MS). Heat stability of amphenicols in matrices was ranked as water >= salt water > soybean sauce > meat, suggesting that heat degradation of amphenicols was accelerated in soybean sauce and was not protected in meat. Heat stability by drug and matrices was ranked as FF > TAP = CAP in water, FF = TAP > CAP in salt water, TAP >= FF = CAP in soybean sauce, and TAP >= FF = CAP in meat, indicating differential heat stability of amphenicols among the 3 drugs and in different matrices. In accordance with the less than 20% degradation, the MIC against Escherichia colt and Staphylococcus aureus did not change after 2 h heating in water. A 5-min heating of amphenicols in water by microwave oven generated comparable percentage degradation to boiling in water bath for 30 min to 1 h. Both CE and GC-MS analysis showed that heating of FF produced TAP but not FF amine as one of its breakdown products. In conclusion, despite close similarity in structure; amphenicols exhibited differential behavior toward heating degradation in solutions and protein matrices. Although higher degradations of amphenicols were observed in soybean sauce and meat, heating treatment may generate product with antimicrobial activity (FF to TAP), therefore, heating of amphenicol residues in food cannot always be assumed safe. (C) 2010 Elsevier B.V. All rights reserved,