Evaluation of a hydrogen laser vacuum ultraviolet source for photoionization mass spectrometry of pharmaceuticals

Abstract

A photoionization hydrogen laser time-of-flight mass spectrometer system (H2-TOFMS) has been evaluated for the rapid analysis of drugs of abuse and pharmaceutical agents extracted from prescription tablets and spiked urine samples. The spectra obtained using the H2-TOFMS showed primarily intact molecular ions (M+*) after introduction by a heated probe and irradiation with vacuum ultraviolet (VUV) photons from the laser. Samples analyzed by this technique required only a simple solid-phase extraction step; no chromatographic separation or derivatization was necessary to identify the drugs of abuse or pharmaceutical agents.

Mass spectrometric study of gas-phase chemistry in a hot-wire chemical vapor deposition reactor with tetramethylsilane

“…Maier et al [33] found that silene was stable only under argon matrix isolation at 10 K and it dimerized to 1,3-disilacyclobutane upon thawing of the matrix at 35 K. In a study of thermal decomposition of 1,1-dimethyl-1-silacyclobutane [34], although kinetic evidence supports the existence of an unstable intermediate, 1,1-dimethyl-1-silene, the only products detected are ethene and 1,1,3,3-tetramethyl-1,3-disilacyclobutane. 1,1-Dimethylsilene, an analog of silene, was found to undergo similar dimerization reactions to yield 1,1,3,3-tetramethyl-1,3-disilacyclobutane: (16) Our study of the hot wire decomposition of silacyclobutane [35] also showed that silene (H 2 Si CH 2 ) was produced, supported by the observation of its dimer signal, 1,3-disilacyclobutane. For the pyrolysis of TMS, 1,1,3,3-tetramethyl-1,3-disilacyclobutane (m/z = 144) [24,29] were previously observed as a product from the analysis by gas chromatography (GC) or GC-MS.…”

“…Non-resonant SPI using VUV wavelengths (100 nm ≤ λ ≤ 200 nm) is generally considered to be a soft ionization method [16][17][18]. Efficient ionization of the chemical species of interest can be achieved by this method with little or no fragmentation.…”

Online Analysis of Biomass Pyrolysis Tar by Photoionization Mass Spectrometry

“…In Figure , the available ionization energies (IEs) of biomass vapors are shown as a function of their molecular mass along with the VUV emission profiles of a commonly used light source, and most of them are distributed in the energy range of 7.8–10.0 eV. Some convenient VUV sources, such as a molecular fluorine laser (F 2 laser) and hydrogen laser (H 2 laser), can emit short pulses at 7.87 and 7.75 eV, respectively. , However, these low photon energies are below the IEs of most biomass vapors (see Figure ). Photon energies of VUV light from an Ar- or Kr-excimer lamp and from a Nd:YAG laser (9.0–10.5 eV) well cover the IEs of most biomass vapors .…”

Laser desorption 7.87 eV postionization mass spectrometry of antibiotics in Staphylococcus epidermidis bacterial biofilms

“…[8]. Postionization of laser desorbed neutrals with 7.87 eV photons from a molecular fluorine laser will single photon ionize various low ionization potential compounds including secondary, tertiary, and aromatic amines as well as various fused ring aromatics, tryptophan containing peptides, and pharmaceuticals [9-11]. Selectivity for specific higher ionization potential species can be achieved by derivatizing a molecular analyte with an appropriate chemical tag to lower the ionization potential of the resultant complex below 7.87 eV, thereby permitting postionization with the fluorine laser [12].…”