Determination of sulfonamides in serum by on-line solid-phase extraction coupled to liquid chromatography with photoinduced fluorescence detection

• On-line SPE coupled to LC with photoinduced fluorescence detection for sulfonamides.
• The anion exchange sorbent for SPE makes compatible the on-line coupling with LC.
• Analysis of 7 sulfonamides in serum previously deproteinized in less than 18 min.
• Relative recoveries between 91.5% and 102.1% with RSD lower tan 10.5%.

An analytical method based on on-line solid-phase extraction coupled to liquid chromatography with photoinduced fluorescence detection has been developed to determine sulfonamides in serum. A home-made setup was used to percolate 3 mL of sample through a solid-phase extraction column. Analytes were retained onto the sorbent by an anion exchange mechanism which ensures an optimum compatibility with the subsequent chromatographic separation using a C-18 column and an on-line photoreactor in order to derivatize sulfonamides, which do not present native fluorescence. The method allowed the determination of 7 sulfonamides in serum samples previously deproteinized in less than 18 min and with limits of detection ranging between 1.8 and 3.6 mg/L. Relative recoveries between 91.5% and 102.1% were obtained with satisfactory precision since relative standard deviations were always below 10.5%.

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