Determination of Trace Mercury in Water Samples by Cloud Point Extraction Coupled with Atomic Fluorescence Spectrometry

A simple, rapid and efficient sample preconcentration method of ultrasonic assisted cloud point extraction ( CPE ) coupled with atomic fluorescence spectrometry ( AFS ) was developed for the determination of trace mercury in water samples. In this method, Thio-Michler’s ketone was used as a chelating agent and Triton X-114 was used as a surfactant to enrich trace mercury in the surfactant phase. Before AFS analysis, tributyl phosphate was added as an antifoam. Under the optimal extraction conditions, such as pH, the amount of chelating agent and surfactant, the detection limit of the method is 0.003 μg/L, the relative standard deviation is 4.2–8.6% and standard recovery rate is 85–106%. The results show that ultrasonic assisted CPE-AFS can be applied to the determination of trace mercury in clean water samples, such as surface water and tap water, with lower detection limit, good accuracy and precision and can meet the requirements of higher sensitivity for sample analysis.