Our research group developed a new material able to retain cadmium, and simultaneously exclude all proteins from biological fluids percolated through it. These biocompatible particles,denominated restricted access carbon nanotubes(RACNTs),were
obtained by the covering of commercial carbon nanotubes(CNTs) with bovine serum albumin(BSA)layers. The BSA molecules were fixed on the CNT surfaces by interconnecting their amine groups, using glutaraldehyde as the cross linker reagent.Thus,when a biological fluid was percolated through a RACNTs'column,in a pH higher than the protein isoelectricpoint,both proteins from the sample and from the BSA layer were negatively charged,causing an electrostatic repulsion,responsible for the protein exclusion. At the sametime,the Cd2þ ions penetrated through the BSA layer,being retained in the CNTs'core. The RACNTs were successfully used as a sorbent in a non-line SPE system toextract Cd2þ directly from untreated human blood serum samples,followed by thermospray flame furnace atomic absorptionspectrometry (TS-FF-AAS)analyses.The samples were analyzed in the
system with out any previous treatment,demonstrating the high efficiency of the sorbent to purify complex matrices.