Sorbent B: Different carbon nanomaterials such as active charcoal,
graphite, carbon nanotubes, and graphene, have been successfully
used in many research fields [19–21]. Nanoporous carbon particles
with very high surface area can be prepared by simple carbonisation
of monodispersed ZIF–8 crystals [17,18]. From N2 adsorption–
desorption isotherms, the surface area of the usedNPC particleswas calculated
to be around 1250 m2 g−1. In order to obtain the functional
groups necessary for analyte retention, this sorbentwas oxidised as Sorbent
A