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

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 mu L of 1-decanol, 450 mu L of THF, 300 mL 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 mu g L-1, 6.32 mu g 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.