Temperature-programmed desorption as a tool for quantification of protein adsorption capacity in micro- and nanoporous materials

The protein adsorption capacity of porous sorbents is generally obtained by measuring the concentration of proteins desorbed from the materials after treatment by a detergent, or by measuring the decrease of protein concentration in the solution. These methods have some drawbacks and often lead to a low precision in the determination of the adsorption capacities. We describe in this paper a new method that allows to directly quantify the amount of proteins adsorbed on porous materials. This method is based on the quantitative analysis by mass spectrometry of some low mass gaseous species which evolve from the biomolecules during the heat treatment of a temperature-programmed desorption analysis (TPD-MS). The method has been applied to bovine serum albumin and cytochrome C adsorbed on an activated carbon. The adsorption uptake of the proteins on the carbon material could be measured by this direct analysis. A comparison with the depletion method was done, it shows that the two methods are complementary. The depletion method allows a determination of the total adsorption capacity, while the TPD-MS method focus on irreversible capacity.