Nitrogen doped nano porous graphene as a sorbent for separation and preconcentration trace amounts of Pb, Cd and Cr by Ultrasonic assisted in-syringe dispersive micro solid phase extraction

Nitrogen doped nano porous graphene was used as an efficient sorbent in solid-phase extraction process for simultaneous separation and pre-concentration of metal ions lead (II), cadmium(II), and chromium(III)) in biological samples. Ultrasonic assisted in-syringe dispersive micro solid phase extraction coupled with micro sampling atomic absorption spectrometry was utilized for the determination of metal ions. Nitrogen doped nano porous graphene was synthesized as a nano sorbent by chemical vapour deposition method. Methane and aniline were used as carbon and nitrogen sources. The characterization of sorbent was performed by field emission scanning electron microscope, transmission electron microscopy, atomic force microscope, fourier transform infrared, chemical element analysis and raman analysis. Effective parameters on the extraction efficiency such as pH, sorbent dosage, eluent volume and eluent concentration were optimized by central composite design and desirability function. Experimental results indicate that the optimal conditions for this extraction were pH=6.4, 1.42mg of sorbent, 100L of eluent, and 0.84mol L-1 of eluent concentration. The detection limits are as low as 1.5, 0.3 and 0.9g L-1 for lead, cadmium, and chromium, respectively. The intra-day precisions were 3.6, 4.38 and 2.94 and Inter-day precision were 4.83, 5.26 and 4.52 for lead, cadmium, and chromium, respectively. Method performance was investigated by determination of mentioned heavy metals in complicated biological matrixes such as human plasma, urine and saliva samples with good recoveries.