Comparison of Cu, Ag, and Au Ions as Ionization Agents of Volatile Organic Compounds at Subatmospheric Pressure.

Ionization of volatile organic compounds (VOCs) by coinage metal ions (Cu, Ag, and Au) generated by laser desorption and ionization (LDI) of a metal nanolayer in subatmospheric conditions is explored. The study was performed in a commercial subatmospheric dual MALDI/ESI ion source. Five compounds representing different VOC classes were chosen for a detailed study of the metal ionization mechanism: ethanol, acetone, acetic acid, xylene, and cyclohexane.

Detection of Single Ag Nanoparticles Using Laser Desorption/Ionization Mass Spectrometry.

The detection of a single entity (molecule, cell, particle, etc.) was always a challenging subject. Here we demonstrate the detection of single Ag nanoparticles (NPs) using subatmospheric pressure laser desorption/ionization mass spectrometry (LDI MS).

Fate of Gold Nanoparticles in Laser Desorption/Ionization Mass Spectrometry: Toward the Imaging of Individual Nanoparticles.

This study focuses on mapping the spatial distribution of Au nanoparticles (NPs) by laser desorption/ionization mass spectrometry imaging (LDI MSI). Laser interaction with NPs and associated phenomena, such as change of shape, melting, migration, and release of Au ions, are explored at the single particle level. Arrays of dried droplets containing low numbers of spatially segregated NPs were reproducibly prepared by automated drop-on-demand piezo-dispensing and analyzed by LDI MSI using an ultrahigh resolution orbital trapping instrument.

Infrared Laser Desorption of Intact Nanoparticles for Digital Tissue Imaging.

We report a new technique for the digital mapping of biomarkers in tissues based on desorption and counting intact gold nanoparticle (Au NP) tags using infrared laser ablation single-particle inductively coupled plasma mass spectrometry (IR LA SP ICP MS). In contrast to conventional UV laser ablation, Au NPs are not disintegrated during the desorption process due to their low absorption at 2940 nm. A mass spectrometer detects up to 83% of Au NPs.

Metal Oxide Laser Ionization Mass Spectrometry Imaging of Fatty Acids and Their Double Bond Positional Isomers.

We present a novel combination of a metal oxide laser ionization mass spectrometry imaging (MOLI MSI) technique with off-line lipid derivatization by ozone for the detection of fatty acids (FA) and their carbon-carbon double bond (C═C) positional isomers in biological tissues. MOLI MSI experiments were realized with CeO and TiO nanopowders using a vacuum matrix-assisted laser desorption/ionization time-of-flight (MALDI TOF) mass spectrometer in the negative mode. The catalytic properties of these metal oxides allow FA cleavage from phospholipids under UV laser irradiation.

Mass Spectrometry Imaging Techniques Enabling Visualization of Lipid Isomers in Biological Tissues.

This Feature focuses on a review of recent developments in mass spectrometry imaging (MSI) of lipid isomers in biological tissues. The tandem MS techniques utilizing online and offline chemical derivatization procedures, ion activation techniques such as ozone-induced dissociation (OzID), ultraviolet photodissociation (UVPD), or electron-induced dissociation (EID), and other techniques such as coupling of ion mobility with MSI are discussed. The importance of resolving lipid isomers in diseases is highlighted.

Metal Ionization in Sub-atmospheric Pressure MALDI Interface: A New Tool for Mass Spectrometry of Volatile Organic Compounds.

A novel approach for the analysis of volatile organic compounds (VOCs) based on chemical ionization by Au ions has been proposed. The ionization is carried out in a commercially available dual sub-atmospheric pressure MALDI/ESI interface without any modifications. The Au ions are generated by laser ablation of a gold nanolayer with the MALDI laser, and VOCs are infused via the ESI capillary.

Gas-aggregated Ag nanoparticles for detection of small molecules using LDI MS.

Several reports demonstrate that silver nanomaterials can serve as surface-assisted laser desorption ionization mass spectrometry (SALDI MS) substrates for low molecular weight analytes. Substrate with tailored silver nanostructures, primarily representing the upmost layer of the bulk, i.e.

Formation of aluminium, aluminium nitride and nitrogen clusters via laser ablation of nano aluminium nitride. Laser Desorption Ionisation and Matrix-Assisted Laser Desorption Ionisation Time-of-Flight Mass Spectrometry.

Laser Desorption Ionisation (LDI) and Matrix-Assisted Laser Desorption Ionisation (MALDI) Time-of-Flight Mass Spectrometry (TOFMS) were used to study the pulsed laser ablation of aluminium nitride (AlN) nano powder. The formation of Al(m)(+) (m=1-3), N(n)(+) (n=4, 5), AlN(n)(+) (n=1-5, 19, 21), Al(m)N(+) (m=2-3), Al(3)N(2)(+), Al(9)N(n)(+) (n=5, 7, 9, 11 and 15), Al(11)N(n)(+) (n=4, 6, 10, 12, 19, 21, 23, and 25), and Al(13)N(n)(+) (n=25, 31, 32, 33, 34, 35, and 36) clusters was detected in positive ion mode. Similarly, Al(m)(-) (m=1-3), AlN(n)(-) (n=1-3, 5), Al(m)N(-) (n=2, 3), Al(2)N(n)(-) (n=2-4, 28, 30), N(n)(-) (n=2, 3), Al(4)N(7)(-) Al(8)N(n)(-) (n=1-6), and Al(13)N(n)(-) (n=9, 18, 20, 22, 24, 26, 28, 33, 35, 37, 39, 41 and 43) clusters were observed in negative ion mode.