Combination of dispersive liquid–liquid microextraction and flame atomic absorption spectrometry for simultaneous preconcentration and determination of manganese and nickel in water and food samples

Abstract

Dispersive liquid–liquid microextraction was developed for the preconcentration and determination of simultaneous manganese and nickel in water and food samples. In this work, an appropriate mixture of ethanol (the disperser solvent) and chloroform (the extraction solvent) was injected rapidly into the aqueous samples containing manganese and nickel. Complex was formed by using 1-(2-pyridylazo) 2-naphtol reagent. The sediment phase was dissolved in 100 µL ethanol and aspirated into the flame atomic absorption spectrometer using a home-made microsample introduction system. Several variables affecting the microextraction efficiency such as pH, concentration of ligand, type and volumes of extraction and disperser solvents were investigated and optimized. Under the optimized conditions and preconcentration of only 10 mL of sample, the enhancement factors of 64.2 and 58.6 and the detection limits of 0.8 and 1.7 µg L−1 were obtained for manganese and nickel, respectively. The relative standard deviations (RSD n = 5) were lower than 4% for both of elements.