“…Above the CPT, the micellar solution separates into two phases: a small volume surfactant-rich phase that contains the analyte, and an aqueous phase containing a low concentration of surfactant. To date, CPE has been widely applied to the extraction of trace metal ions from various matrices through the formation and pre-concentration of chelates (Labrecque, Whitty-Leveille, & Lariviere, 2013;Silva, Roldan Pdos, & Gine, 2009;Ulusoy, Akcay, Ulusoy, & Gurkan, 2011). There are several reports of CPE as a pre-concentration step for the determination of Se by different spectrometric techniques, including spectrophotometry (Soruraddin, Heydari, Puladvand, & Zahedi, 2011;Wen, Zhang, Li, Fang, & Zhang, 2014), spectrofluorimetry (Güler, Maden, Bakırdere, Yavuz Ataman, & Volkan, 2011), graphite furnace atomic absorption spectrometry(GF-AAS) (Sun, Liu, & Wu, 2013), electrothermal atomic absorption(ET-AAS) (Ghambarian,Yamini,Saleh,Shariati,& Yazdanfar,3 2009; Li, Hu, He, & Xiang, 2008;Sounderajan, Kumar, & Udas, 2010) and electrothermal vaporization inductively coupled plasma mass spectrometry(ETV-ICPMS) (Chen, Hu, & He, 2006;Li et al, 2008).…”