These experiments were carried out to develop a novel, simple, and rapid method to determine urinary sulfonamides using fluorescamine by spectrofluorometry. To get optimal conditions for the sulfonamide-fluorescamine reaction, sulfonamides such as sulfamethazine, sulfamerazine, sulfadimethoxine and sulfamonomethoxine, dissolved in buffers with various pH ranges were reacted with various concentrations of fluorescamine. and then, the fluorescence intensity and stability of the fluorophore were measured. To eliminate the interfering substances in urine, the fluorophore in buffers and urine with a definite pH range was extracted with some organic solvents. After then the fluorescence intensity was measured in organic and aquous phases.
The results obtained were summarized as follows:
1. The maximal fluorescence of sulfonamides was presented in acidic state, pH 4.5∼5.0, at 30 minutes after reaction.
2. The optimal concentration ratio of sulfamethazine and ffuorescamine was more than 1 : 40 in mole.
3. In pH 4.0, the intensity was maximal but was time-dependent, whereas in pH 8.0, the intensity was time-independent.
4. Sulfamethazine-fluorescamine conjugate could be dissolved in some of organic solvents in acidic state such as chloroform, n-butanol, and ethylacetate.
5. Sulfamethazine-flnorescamine conjugate in swine urine coule be extracted with ethylacetate in acidic state, pH 4.0∼5.0.
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