Influence of chloride ion on sers of humic substances adsorbed on silver sols

The SER spectra of humic substances in neutral pH and low concentrations typically found in natural environment could be conveniently observed while a laser-reduced silver colloid made from AgNO3 was used. However, their SER signals were weaken and then scavenged as a small amount of KCl was progressively added. Therefore, it was suggested that a desalted procedure was helpful for trace detection of humic substances in real environment by SER spectroscopy while silver sols were used for the substrates.