Fig. 4From: Comparing silver and gold nanoislands’ surface plasmon resonance for bisacodyl and its metabolite quantification in human plasmaSEIRA spectra of the mixture number 21 of equal concentrations (120 ng/mL) of BIS and its active metabolite on the surface of AgNPs and nanoparticle-coated coated glass slides. The same concentration of the mixture was measured on the surface of glass slides soaked for 1, 2, 3, and 4 h in solutions of Cit-AgNPs and Cit-AuNPsBack to article page