A process is provided for capturing or concentrating microorganisms for detection or assay. The process includes providing an adsorption buffer-modified inorganic concentration agent, providing a sample including at least one microorganism strain, and contacting the adsorption buffer-modified inorganic concentration agent with the sample such that at least a portion of the at least one microorganism strain is bound to or captured by the adsorption buffer-modified inorganic concentration agent. The adsorption buffer-modified inorganic concentration agent is prepared by a process including contacting at least one inorganic concentration agent with at least one cation-containing salt solution, so as to wet at least a portion of the inorganic concentration agent, and drying the resulting wet inorganic concentration agent.