Iron oxide functionalized graphene nano-composite for dispersive solid phase extraction of chemical warfare agents from aqueous samples

• A magnetic nano-composite of graphene was synthesized and characterized.
• Nano-composite was exploited as magnetic dispersive solid phase extraction sorbent.
• Chemical Weapons Convention relevant chemicals were extracted from aqueous samples.
• LOD ranged from 0.11 to 1.29 ng mL−1.

Present study deals with the preparation and evaluation of graphene based magnetic nano-composite for dispersive solid phase extraction of Chemical Weapons Convention (CWC) relevant chemicals from aqueous samples. Nano-composite, Fe3O4@SiO2-G was synthesized by covalently bonding silica coated Fe3O4 onto the graphene sheets. Nerve agents (NA), Sulfur mustard (SM) and their non-toxic environmental markers were the target analytes. Extraction parameters like amount of sorbent, extraction time and desorption conditions were optimized. Dispersion of 20 milligram of sorbent in 200 mL of water sample for 20 min. followed by methanol/chloroform extraction produced average to good recoveries (27–94%) of targeted analytes. Recoveries of real agents exhibited great dependency upon sample pH and ionic strength. Sarin produced maximum recovery under mild acidic conditions (56% at pH 5) while VX demanded alkaline media (83% at pH 9). Salts presence in the aqueous samples was found to be advantageous, raising the recoveries to as high as 94% for SM. Excellent limits of detection (LOD) for sulphur mustard and VX (0.11 ng mL−1 and 0.19 ng mL−1 respectively) proved the utility of the developed method for the off-site analysis of CWC relevant chemicals.