The evaluation of the potential of nanoparticles (NP) for adsorbing biomolecules and use of control approaches are important for accurate presentation of in vitro analytical data. In this study, seven types of NP including carbon black (CB), cerium dioxide (CeO2), copper oxide (CuO), indium trioxide (In2O3), nickel oxide (NiO), silicon dioxide (SiO2), and titanium dioxide (TiO2) were used for determining the adsorption ability of interleukin-8 (IL-8) under either (1) a cell-free condition where NP were incubated with supernatant of A549 cells, or (2) a cell-based condition, where cells were treated with NP. Under the cell-free condition, CB and TiO2 NP showed a high adsorption affinity for IL-8 in supernatants of both lipopolysaccharide (LPS)-stimulated and unstimulated A549 cells. In contrast, SiO2 and In2O3 NP displayed a relatively low adsorption affinity. Further, IL-8 adsorption was markedly reduced when NP were predispersed in fetal bovine serum. The results obtained under cell-based conditions using both stimulated and unstimulated cells were consistent with those of the cell-free condition. Data indicate that adsorption of IL-8 onto NP surface is variable depending on type of NP, preparation method of NP, and cellular inflammatory state. Thus, the cell-free adsorption assay may be utilized for reliable interpretation of data produced by in vitro cell-based methodology.