The RACNTs presented high Pb2þ extraction capacity from human serum samples, without previous sample preparation
steps. It was also confirmed that the metal ions penetrate through the BSA layer, being preferably retained in the CNT core. It was also possible to perform a full and fast protein exclusion in the present system. The RACNTs' column could be used for more than 200 sequential extractions of Pb2þ, without losing the analyte extraction efficiency. The enrichment factor allowed the Pb2þ quantification at the μg L1 level. Other advantages can be pointed out like the low limit of quantification, good precision and accuracy,high analytical frequency, as well as low reagent and sample consumptions. The RACNTs can also be employed in direct extractions of inorganic and/or organic analytes from several and complex samples.