Hollow-fiber liquid-phase microextraction combined with capillary electrophoresis for trace analysis of sulfonamide compounds

• A HF-LPME/CE-ED method has been developed for trace analysis of six sulfonamides.
• The LODs (0.033–0.44 ng/mL) were significantly improved by applying HF-LPME.
• The six sulfonamides could be preconcentrated up to 996-fold.
• The sulfonamides in water samples can be directly determined without derivatization.

A hollow-fiber liquid-phase microextraction (HF-LPME) method has been developed for the preconcentration of trace sulfonamides in water samples. Six commonly used sulfonamides including sulfamethazine (SMZ), sulfamerazine (SMR), sulfadiazine (SDZ), sulfadimethoxine (SDM), sulfamethoxazole (SMX), and sulfathiazole (STZ) were determined by CE with electrochemical detection (CE-ED) after microextraction. Several factors that affect extraction efficiency, separation, and detection were investigated. Under the optimum conditions, above sulfonamide compounds could achieve baseline separation within 35 min, exhibiting a linear calibration over three orders of magnitude (r2 ≥ 0.998); the obtained enrichment factors were between 121 (for SDZ) and 996 (for SDM), and the LODs were in the range of 0.033–0.44 ng/mL. The proposed HF-LPME/CE-ED method has been applied for the sensitive analyses of the real-world water samples with recoveries in the range of 75.1–109%.