Ultrasound-assisted cloud point extraction for the determination of sulfonamides in honey samples by fluorescence spectrophotometry
An ultrasound-assisted cloud point extraction (UA-CPE) method using nonionic surfactant nonylphenol ethoxylate (NP-7) as the extractant was developed for determination of two sulfonamides (SAs, sulfadiazine sodium and sulfamerazine) in honey samples. The procedure was based on the derivatization SAs in honey with fluorescamine yielding fluorescent complexes, which were extracted into the surfactant-rich phase and analyzed by molecular fluorescence spectrophotometry. The polar of SAs of derivatives was reduced and strong fluorescence was produced at λex = 410 nm. Variable parameters affecting the derivatization and UA-CPE procedure were evaluated and optimized. The calibration graph was linear from 10 to 10 000 ng mL−1 with coefficient of determination more than 0.9991. The limits of detection (LOD) were 0.5 ng mL−1 for sulfadiazine sodium and 5.0 ng mL−1 for sulfamerazine with the relative standard deviations of the method ranging from 2.2% to 4.1%. Recoveries of the compounds on spiked honey samples at fortified level of 1 μg mL−1 were 92.2% for sulfadiazine sodium and 84.1% for sulfamerazine, respectively. Therefore, the developed method is practical and reliable, with potential application to determine the content of SAs in honey samples.