Sulfonamides physicochemical methods

If tlie identity of the detected drug residue is still unknown after these tests have been performed, a TLC-bioautography procedure is then applied to isolate and tentatively identify the residues (64, 72). This method is not quantitative and only gives direction to the analyst as to what determinative/confirmatory method of analysis should be used. Following this tentative identification, presumptive positives are then quantified and confirmed by validated physicochemical methods. A TLC method (73) is applied for analyzing presumptive sulfonamide residues, a GC-ECD method (74) followed by a GC-MS NCI method (75) for analyzing chloramphenicol, and LC/UV methods (76,77) for analyzing -lactams and tetracyclines. 

Physicochemical Methods for Sulfonamides and Diaminopyrimidine Potentiators in Edible Animal... 

In subsequent studies attempting to find a correlation of physicochemical properties and antimicrobial activity, other parameters have been employed, such as Hammett O values, electronic distribution calculated by molecular orbital methods, spectral characteristics, and hydrophobicity constants. No new insight on the role of physiochemical properties of the sulfonamides has resulted. Acid dissociation appears to play a predominant role, since it affects aqueous solubiUty, partition coefficient and transport across membranes, protein binding, tubular secretion, and reabsorption in the kidneys. An exhaustive discussion of these studies has been provided (10). 

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