A Novel Dispersive Liquid-Liquid Microextraction Method Based on Solidification of Floating Organic Drop for Preconcentration of Pd(II) by Graphite Furnace Atomic Absorption Spectrometry after Complexation by a Thienyl Substituted 1,2-Ethanediamine

Abstract

A novel dispersive liquid-liquid microextraction method based on solidification of floating organic drop (DLLME-SFO) was developed for the preconcentration of ultratrace amounts of palladium (Pd)(II) before its determination by electrothermal atomic absorption spectrometry. Diphenyl ether (m.p. 26°C) was used for the first time as a heavier than water organic solvent in the developed method. Pd was complexed by N,N′-bis(thiophen-2-ylmethylene)ethane-1,2-diamine to be extracted into the dispersed diphenyl ether phase using acetonitril as the disperser solvent. Upon cooling and centrifugation, the organic solvent was sedimented at the bottomn and the aqueous phase was easily decantated. Some factors influencing the extraction efficiency of Pd(II) and its subsequent determination, including extraction and dispersive solvent type and volume, pH of sample solution, concentration of the chelating agent and salting out effect, were studied and optimized both with univariate and multivariate methods. Under the optimized conditions, the calibration graph exhibited linearity over a range of 10 – 120 µg L⁻¹. The enrichment factor was 83.3, the detection limit for Pd (3σ) was 47 ng L⁻¹ and the relative standard deviation was 3.2% (n = 10, 1 ng mL⁻¹). The method was successfully applied to the determination of trace amounts of Pd(II) in water samples.