Supramolecular solvent-based microextraction method for cobalt traces in food samples with optimization Plackett–Burman and central composite experimental design

Abstract

A new microextraction method based on formation of supramolecular solvent (Ss) was developed by using of chemometric optimization method for cobalt determination with microsampling flame atomic absorption spectrometry (MS-FAAS). 1-Decanol/THF was used to obtain supramolecular solvent, which ensure the formation of micelles in the nano and molecular size and to transfer the diethyldithiocarbamate (DDTC)–cobalt(II) complex from the aqueous phase to the extraction phase media. The optimization strategy was carried out by using of Plackett–Burman Design (PBD) and Central-Composite Design (CCD). Statistically significant parameters such as pH, the volume of ligand (DDTC), the volume of supramolecular solvent (1-decanol/THF) and centrifugation time were investigated by using of Plackett–Burman design. Central-composite design was used to determine optimal condition of these parameters. The optimum experimental conditions obtained were pH 6, 125 μL of 1-decanol, 450 μL of THF, 300 μL of DDTC (0.1%, w/v) and 8 min of centrifugation time. The relative standard deviation (RSD), limit of detection (LOD), limit of quantitation (LOQ) and preconcentration factor (PF) were 1.51% (n = 8, 94–98%), 1.89 μg L⁻¹, 6.32 μg L⁻¹ and 30 respectively. The method were applied to the certified reference materials of TMDA 53.3 water, TMDA 64.2 water, SPS-WW2 waste water, Oriental Basma Tobacco Leaves (INCT-OBTL-5) and scallion (salad onion), (NCS ZC73033) to validation. The microextraction method was also successfully applied to determine cobalt concentrations by microsampling FAAS in water, cereal, powdered beverage and fruit samples.