Cephalosporins are antibiotics with the same fundamental structural as penicillin. They are used to treatment of infections caused by Geram-positive and Geram-negetive bacteria. In this work, dispersive liquid- liquid microextraction coupled with high performance liquid chromatography-diode array detector (HPLC-DAD) were applied for the extraction and determination of cephalosporins (cefazolin, cefotaxime andceftizoxime) in water samples. For the microextraction, extraction solvent (chloroform) was injected into a 10 mL glass tube with conical bottom containing aqueous solution of hexa decyl-trimethyl-ammonium bromide and cephalosporins. After centrifugation, the sedimented phase was complectely transferred to another tube with conical bottom using a 100 ?L syringe. 25 ?L water was added into the sedimented phase and finaly 20 ?L of the solution was injected into the HPLC. In order to obtain optimum conditions of the microextraction, several parameters affecting on the microextraction such as: surfactant type, extraction solvent type, percentage of surfactant, pH , sedimented phase volume, salt addition and time of the extraction were studied. Under optimum conditions for microextraction (extracting solvent, chloroform? amount of surfactant, in 0.1mM? sedimented phase volume, 34 ?L? pH, 4? without salt addition). Enrichment factors and limit of detections (LODs) were ranged 3.3-7.5 and 24-27?g/L, respectively. The proposed method was used for analysis of rael samples such as zayandeh rood (Esfahan) river water, human wastewater, industrial wastewater and wastewater effluent of folad mobarake steel complex.
