A Novel Automated Online SPE-Coupled CE System for the Analysis of Sulfonamide Antibiotics in Wastewater

A novel automated online SPE-coupled CE system with high precision has been developed, in which a four-port nano-valve served as an interface. With this system, 10 mL of pretreated water sample was introduced to the online SPE column, and the analytes were preconcentrated. After the cleanup step, the analytes were eluted, and a quantitative volume of the elution plug was injected in the capillary by switching the four-port nano-valve for CE separation. The experimental parameters, including the position of the four-port nano-valve, separation conditions, sample loading flow rate, sample volume, elution flow rate and four-port nano-valve switch time were optimized in detail. The effectiveness of the system was demonstrated by the analysis of six sulfonamide antibiotics in water samples. Good linear ranges were obtained with correlation coefficients from 0.9983 to 0.9997. The intra- and inter-day relative standard deviations were below 4.6 and 5.8%, respectively. The limits of detections were in the range of 2.22 to 3.35 ng mL^?1. This proposed method was successfully applied to the analysis of effluent and influent water from a wastewater treatment plant, and the average recoveries of the wastewater samples ranged from 77.3 to 92.0%.