Articles and methods involving detection of binding between two or more species using MALDI are generally provided. In some embodiments, a method comprises exposing a first species to a composition comprising a second species, capturing the first species on a self-assembled monolayer, and performing MALDI on the self-assembled monolayer to generate a signal from the second species and a signal from a standard species present in the self-assembled monolayer. A ratio (first ratio) of the signal from the second species to the signal from the standard species may be compared to a cutoff value in order to determine if binding has occurred. This method may allow determination of a relative affinity of the second species for the first species.