simultaneous determination of 2-nitrophenol and 4-nitrophenol in pharmaceutical industrial wastewater by electromembrane extraction coupled with hplc-uv analysis

Background: in the present study, an electromembrane extraction (eme) followed by a simple high performance liquid chromatography with ultraviolet detection (hplc-uv) was developed and validated for simultaneous determination of 2-nitrophenol (2-np) and 4-nitrophenol (4-np) in pharmaceutical industrial wastewater sample. main parameters of electromembrane extraction were evaluated and optimized. methods: 1-octanol was immobilized in the pores of a polypropylene hollow fiber as supported liquid membrane. as a driving force, a 100 volt electrical voltage was applied to transfer the analytes from the sample solution (ph, 7.5) through the supported liquid membrane into an acceptor solution (ph, 12). results: the best enrichment factors were obtained 36 and 72 for 2-np and 4-np, respectively after 15 minutes of extraction. the effect of carbon nanotube, as a solid nano-sorbent on eme efficiency, was also evaluated. the proposed method provided the linearity in the range of 10-1000 ng/ml for 2-np (r²> 0.9997) and 4-np (r²> 0.9999) with repeatability range (% rsd) between 2.6-10.3 % (n = 3). the limit of detection was 3 ng/ml and the limit of quantitation was 10 ng/ml. conclusion: finally, the method was applied for the determination of 2-np and 4-np in industrial wastewater samples with relative recoveries in the range between 67–76 %. eme improved the sensitivity of hplc-uv for the determination of trace concentrations of these analytes.