Fluorimetric Determination of Trace Sulfonamides in Milk Samples

Abstract

A precise and reliable fluorimetric method for the determination of four sulfonamide antibiotics (sulfadiazine, sulfaguanidine, sulfamethoxazole, sulfamethazine) in milk samples has been developed. Sulfonamide in presence of o-phthalaldehyde produces an isoindole derivative, which can produce strong fluorescence. N-butanol was used for the extraction of the derivative to bring down the detection limit largely. Optimum conditions for the determination of sulfonamides were also investigated. Fluorimetric detection was carried out at l_ex of 295 nm and l_em of 425 nm. Linear ranges for sulfonamides determination were 5-500 mg/L. The developed method is practical and can be successfully applied to determine the content of sulfonamides residues in milk samples with satisfactory results.