was
applied for the extraction and preconcentration of various standard solutions of cobalt(II) and the calibration graph was linear in
the range of 2–100 mg L1. The LOD, defined as 3Sb/m (where Sb
and m are the standard deviation of the blank and the slope of the
calibration graph, respectively) , was found to be 0.2 mg L1. The
preconcentration factor that was calculated by dividing the aqueous phase volume in to the final volume of the diluted phase was 50. Repeatability was carried out by spiking blank samples at the concentration of 50.0 mg L1, and the relative standard deviation
(RSD) for ten replicate experiments was 2.2%.