Application of portable tungsten coil electrothermal atomic absorption spectrometer for the determination of trace cobalt after ultrasound-assisted rapidly synergistic cloud point extraction

In this work, ultrasound-assisted rapidly synergistic cloud point extraction (UARS-CPE) was firstly established and combined with a portable tungsten coil electrothermal atomic absorption spectrometer (W-coil ET-AAS) for preconcentration and determination of trace cobalt. As a new instrument, the application of the portable W-coil spectrometer was expanded through the coupling with UARS-CPE, which was accomplished at room temperature rapidly by the effect of ultrasound and revulsant/synergic reagent. The instrumental conditions and influencing factors relevant to UARS-CPE efficiency, such as concentrations of surfactant and chelating agent, volume of revulsant/synergic reagent, pH, and ultrasound extraction time were studied systematically. The coupling improved the analytical performance of the portable spectrometer considerably. Under the optimal conditions, the limit of detection (LOD) for cobalt was 0.30 μg/L, with sensitivity enhancement factor (EF) of 52. In order to validate its application in field analysis, some environmental water samples were field-analyzed with satisfactory results. The established method could be expanded to pre-concentrate and detect many other trace metal ions.