Another parameter that plays an important role in the EIEB procedure is the concentration of nitric acid in the extraction solution.
In general, the acids prevent hydrolysis of the metallic ions and also convert organic species, metallic solid particles, and oxide species of the analytes into their inorganic forms.
Additionally, acidified samples in the emulsifications procedures give direct correlation between the signal of the analyte in the samples and its signal in aqueous inorganic standards.
When the acidic medium was used, the organic matrix is not destroyed; only element extraction is carried-out (Burguera & Burguera, 2012).
Different inorganic acids are used for emulsion preparation, although nitric acid is preferred in most cases.