Silver nanoparticles were modified with 1-octadecanethiol (1-ODT)/4-amino thiophenol (4-AMP) and 1-ODT/1-thioglycerol (1-TG) to prepare Ag@ODT/AMP and Ag@ODT/TG, respectively . The materials were used in microextraction as a pseudo-stationary phase via single-drop microextraction (SDME). They can extract proteins and peptides e.g., insulin, ubiquitin, cytochrome c, cysteine, homocysteine, and lysozyme. The separated proteins can be detected after extraction using MALDI-MS. The method can be used for the analysis of real samples e.g., urine and milk . Silver ferrite iron oxide nanoparticles (AgFeO2 NPs) were reported for biothiols separation . AgFeO2 and AgFeO2 modified chitosan (AgFeO2@CTS NPs) can be used for the separation of biological thiols e.g., sulfamethizole, thiabendazole, dithiothreitol, and glutathione before the analysis using MALDI-MS and surface assisted laser desorption/ionization mass spectrometry (SALDI-MS) .