On-line flow-injection liquid-phase microextraction and spectrophotometric determination of traces of copper(II) with trithia-9-crown-3 as complexing agent.

A novel on-line flow-injection liquid-phase microextraction (FI-LPME) and spectrophotometric determination of the Cu(2+) ion using trithia-9-crown-3 (TT9C3) as a sensitive and selective charge transfer complexing agent was developed. After phase segmentation by pulsating motions of a peristaltic pump, the phase separation takes place by the aid of gravitation forces. The optimum values of the pH (= 5 of phosphate buffer) and ionic strength (5 mM Na2SO4) of the solution, amount of ligand (2.0 × 10(-3) mol L(-1)), nature of the counter ion (10 mM SDS), volume of the organic solvent (150 μL), coil length (3 m) and extraction time (2 min) for an efficient extraction were determined. The calibration curve was found to be linear over a concentration range of 0.008 - 4.2 μg mL(-1) (R(2) = 0.9985) with a limit of detection of 0.37 ng mL(-1). The enrichment factor and relative standard deviation (n = 7) were 16 and 5.7%, respectively. Finally, the proposed method was applied to the determination of copper(II) as an impurity in the several commercial metallic salts.