Highly selective determination of trace quantities of mercury in water samples after preconcentration by the cloud-point extraction method

A cloud-point extraction method for preconcentration of ultra-trace quantities of mercury ions as a prior step to its determination by spectrophotometry. The method is based on the cloud-point extraction of mercury in iodide media with Triton X-114. The preconcentrated mercury was then determined spectrophotometrically by measuring the absorbance of the surfactant rich phase at 300 nm and also by cold-vapour atomic absorption spectrometry (CVAAS). Linearity was obeyed in the range of 0.40–40.0 ng mL−1 by CVAAS and in the range of 10.0–400.0 ng mL−1 by spectrophotometry. The detection limit is 3.0 ng mL−1 by spectrophotometry and 0.10 ng mL−1 by CVAAS. The interference effect of several anions and cations was also tested. The method was used to determine mercury in water samples.