Determination of cadmium in bread and biscuit samples using ultrasound-assisted temperature-controlled ionic liquid microextraction.

In the present work, a simple and rapid method was proposed for the preconcentration of cadmium using ultrasound-assisted temperature-controlled ionic liquid microextraction (TC-IL-LPME). The dispersion of the ionic liquid (1-Hmim[PF6 ]) in the aqueous phase was performed by heating it in an ultrasonic bath, followed by cooling in an ice bath. After centrifugation, the enriched phase was dissolved in 45% (w/w) nitric acid solution to reduce viscosity, and the cadmium content was measured employing electrothermal atomic absorption spectrometry (ET-AAS). The 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol reagent (Br-PADAP) was used as a complexing agent. Under optimized conditions, the method had a detection limit of 2.0 ng L-1 and an enrichment factor of 24. The accuracy of the method was evaluated through the analysis of the certified reference material of brown bread (BCR-191). The method was applied to the determination of cadmium in samples of bread and biscuit. The limit of detection of the solid samples was 0.10 μg kg-1 . The recovery of cadmium in the samples varied between 93% and 107%. The proposed method is presented as a simple, cheap, ecological and a sensitive alternative for the determination of cadmium in bread and biscuit samples. © 2019 Society of Chemical Industry.