However, the effect of
the pH or salt concentration of the soaking solution
upon the ability of each SPR to detect latent
fingerprints has never been investigated. In this
study, various types of surface samples soaked in
each different solution (tap water, weak acid, weak
base, and various concentrations of sodium chloride),
which represents water from some of the different
available sources, was used to evaluate the effect on
latent fingerprint detection by SPR.