A simple preconcentration method for highly sensitive determination of Pb in bee products by magnetic ionic liquid dispersive liquid-liquid microextraction and electrothermal atomic absorption spectrometry

Abstract

A highly efficient preconcentration method based on the dispersive liquid-liquid microextraction technique (DLLME), that incorporated a magnetic ionic liquid (MIL) as extractant and electrothermal atomic absorption spectrometry (ETAAS) detection, was developed to determine Pb at ultra-trace levels in different bee products. Initially, the analyte was chelated with 1,5-diphenylcarbazide in 2 mol L-1 HCl and extracted by 150 μL of trihexyl(tetradecyl)phosphonium tetrachloromanganate (II) ([P6,6,6,14]2MnCl4). Subsequently, the extractant phase was separated by a magnet and an aliquot was injected into the graphite furnace of ETAAS. Phase separation was possible without a centrifugation step by using a MIL, thus reducing the analysis time and simplifying the proposed method. Under optimal experimental conditions, an extraction efficiency of 97% and a sensitivity enhancement factor of 107 were obtained. A detection limit (LOD) of 3 ng L-1 with a relative standard deviation of 3.6% (at 100 ng L-1 Pb, n = 10) and a linear range of 10-3000 ng L-1 were obtained. This work reports the first application of the MIL [P6,6,6,14]2MnCl4 along with the DLLME technique for the determination of Pb at trace levels in different bee products, such as honey, mead, honey vinegar and honey beer.