A Fluorescence-LC Method for the Determination of Sulfonamides in Biological Fluids with Pre-Column Derivatization

A new, sensitive and selective LC method has been developed and validated for the simultaneous determination of eight sulfonamides, in the presence of putrescine as internal standard, after pre-column derivatization with fluorescamine. The derivatives were separated on an Inertsil ODS-3 (250 × 4 mm I.D., 5 μm) column using a 20 min gradient elution with a binary system of methanol–0.05 M acetate buffer (pH 3.4) and fluorescence detection at excitation and emission wavelengths of 406 and 496 nm, respectively. Linearity of derivatization was obtained for concentrations from 1.0 to 300 μg L−1 in standard solutions. The method was applied to the determination of sulfonamides in human serum and urine after solid-phase extraction and subsequent derivatization of the extracts. The detection limits varied from 0.250 to 0.300 μg L−1 in serum and 0.100 to 0.250 μg L−1 in urine samples. The average recoveries ranged from 91.2 to 119.0 and 91.3–117.0 in serum and urine samples, respectively.