Sodium(I)-doped graphitic carbon nitride with appropriate interlayer distance as a highly selective sorbent for strontium(II) prior to its determination by ICP-OES.

Multilayered and porous sodium-doped graphitic carbon nitride (GCN-Na) was prepared and employed to the solid-phase extraction of Sr(II). The sorbent exhibits high adsorption capacity and excellent selectivity for Sr(II). This is due to its small interplanar stacking distance caused by doping with Na(I) which matches the size of Sr(II) better than blank GCN. An original solid-phase extraction method based on GCN-Na coupled with ICP-OES was established for Sr(II), the calibration plots are linear ranging from 0.05-10 mg·kg-1 with the correlation coefficients (R2) above 0.999, the limits of detection are in the range of 0.57-1.52 μg·kg-1 and the preconcentration factor of 80 is achieved using 48 mL sample. It was successfully applied in the extraction and detection of trace Sr(II) in tap water, rice and sea fish. Graphical abstractA multilayer porous sodium(I) doped graphitic carbon nitride nanosheet (GCN-Na) was synthesized and exhibited excellent adsorption capability and selectivity for Sr(II).