Sputter-Coated Metal Screening for Small Molecule Analysis and High-Spatial Resolution Imaging in Laser Desorption Ionization Mass Spectrometry

rMSIcleanup: an open-source tool for matrix-related peak annotation in mass spectrometry imaging and its application to silver-assisted laser desorption/ionization

“…true negatives) located in mass ranges with no signal. We propose this validation strategy as a novel alternative to more common validation approaches such as chemical standards [6] or expert annotation [11,35]. This study adds to previous work [6,14,17,29,38] and further demonstrates the potentiality of AgLDI MS imaging, a thriving technology known for its reduced background signals in spatial metabolomics that is strongly complemented by our annotation algorithm as it further removes the influence of the matrix.…”

“…Dataset 12 contains 60 identifications by MS/MS [14]. Dataset 13 contains 4 metabolites identified by MS/MS and a total of 10 tentatively identified formulae based on exact mass [6]. Dataset 14 contains 10 metabolites identified by MS/MS and 6 tentatively identified formulae based on exact mass [6].…”

“…Nanomaterials or metal layer deposition methods, for instance, dramatically reduce the number of signals related to the LDI promoting material in the low m/z range. Some examples are graphene oxide, silicon or metals such as gold, platinum or silver [5][6][7][8]. Nevertheless, even when these alternatives are used and the number of peaks related to the LDI promoting material is reduced, there is still a need to annotate them in order to reduce spectral complexity and distinguish exogenous from endogenous compounds, especially in untargeted applications.…”

“…In order to validate and optimize the proposed method, we opted for a well-understood LDI promoting material such as silver. The use of silver nanolayers for MSI (AgLDI MSI) has been steadily growing in recent years [6,[12][13][14][15][16][17]. The characteristic isotopic pattern of silver ( 107 Ag and 109 Ag , 51.84% and 48.16% abundance, respectively), as well as its well-known ionization and adduct formation allow to define a list of possible and not-possible silver-related peaks of a typical AgLDI MSI experiment.…”

Potential of triacylglycerol profiles in latent fingerprints to reveal individual diet, exercise, or health information for forensic evidence

“…The TM Sprayer method included 8 passes at 30 C with a ow rate of 0.03 mL min À1 and a linear velocity of 1200 mm min À1 . The gold sputter coating was done at 40 mA for 10 seconds ($2.8 nm thickness) 25 on a 108 Auto Sputter Coater (Ted Pella Inc. Redding, CA). The combination of spraying sodium acetate and sputter coating with gold was modied from a previously reported method.…”