Cloud point-dispersive liquid-liquid microextraction for preconcentration and determination of mercury in wastewater samples by methylsulfanyl thiophenol material

A efficient method based on 4-methylsulfanyl thiophenol (MSTP, C7H8S2) and ionic liquid ([BMIM][PF6]) was used for mercury (Hg) separation and preconcentration from wastewater of petrochemical industries. The 0.01 mile molar of MSTP, 80 mg of [BMIM][PF6] was diluted with 0.2 mL of ethanol (Et 98%). The mixture was injected to 10 mL of wastewater samples, shacked by ultrasonic bath for 5.0 min and cloudy solution was achieved by ionic liquid micelles at pH=7.0. The mercury ions was complexed with MSTP and extracted on micelles (IL/Et) by cloud point dispersive liquidliquid microextraction (CP-DLLME) at 50oC before determined by cold vapor atomic absorption spectrometry (CV-AAS). The favorite extraction for mercury with low LOD (15 ng L-1) and good linear rages (0.05- 6.2 μg L-1) was achieved (RSD<5%). The main parameters such as, pH, sample volumes, amount of MSTP, amount of IL and ultra-sonic time were optimized. The method validated by spiking samples and certified reference material (CRM, NIST) in water sample.