Velocity Distributions for a Laser-Vaporized, Anthracene-Labeled Nucleotide

Abstract

We report the laser vaporization and multiphoton ionization of two anthracene-labeled molecules, W(6-hydroxyhexyl)-3-(9-anthryl)propionamide and an anthracene-linked deoxythymine monophosphate. Laser vaporization of the anthracene-containing molecules was performed by directing a high-intensity pulse (30-300 mJ/cm2, 2.5 ns) of 532 nm laser light into a thin film of rhodamine 6G (Rh 6G) containing nanomolar quantities of the sample. Resonance-enhanced multiphoton ionization was used to selectively ionize the anthracene moiety in each molecule after vaporization. The So-SI transition of the anthracene molecule at 361 nm was used to excite the molecules, and ionization from this intermediate state was achieved using a 308 nm photon. The ionized products were detected and analyzed by mass spectrometry. The time-ofarrival measurements for the laser-vaporized molecules correspond to a bimodal velocity distribution, composed of a thermal component and a hyperthermal component showing substantial translational energy cooling. The distributions for the anthracene-labeled molecules reveal lower most probable velocities than those for the Rh 6G. A photochemical laser ejection model is proposed to account for the energetic nonthermal velocity distributions measured.

New derivatization strategies for the ultrasensitive analysis of non-aromatic analytes with APLI-TOF-MS

“…This approach is also used for other ionization techniques in mass spectrometry to enhance or enable ionization [9,28,29]. The earlier presented APLI labels from our group are based on anthracene and are connected via a spacer to an anchor group which can be coupled to several functional groups.…”

“…NHS esters (4) are also used for the derivatization of amines. This derivatization is performed under mild conditions and is prone to the presence of water; in fact, it is used for labeling analytes in aqueous solutions [24,29]. Figure 5 shows the analysis of propylamine (250 nM) labeled with 3.…”

Vacuum ultraviolet photoionization of carbohydrates and nucleotides

“…A motor attached to the front of a Jordan Co. pulse valve rotates and translates the drum so that fresh sample powder is gently desorbed by each 532 nm laser pulse. [19][20][21][22][23] In particular, use of the R6G matrix has been demonstrated [18][19][20][21][22] to be a very effective approach for desorbing and vaporizing molecules without fragmentation. The desorbed sample is carried to the ionization region of a time of flight (TOF) mass spectrometer using supersonic expansion of He gas (40 psi backing pressure), and is collimated by a skimmer with the aperture diameter of 1 mm.…”

“…By studying carbohydrates and nucleotides separately, one can, in principle, determine the component of DNA and RNA that is responsible for nucleic acid radiation sensitivity and ensuing damage. Chemically modified nucleotides have previously been generated 18 in the gas phase through laser desorption; however, to the best of our knowledge, the current study involves the first experiment in which unlabeled, isolated nucleotides are prepared in the gas phase through a similar technique. Density functional theory calculations are also employed for analysis of experimental findings.…”

7.87 eV laser desorption postionization mass spectrometry of adsorbed and covalently bound bisphenol a diglycidyl methacrylate

“…Previous work demonstrated that aromatic tagging can be used to facilitate resonant multiphoton ionization of analytes whose underivatized counterparts cannot be similarly detected [27][28][29][30]. Several of the authors previously used a similar strategy to show that aromatic tagging of molecular analytes lowers the overall IP of the tagged molecular complex, allowing 7.87 eV SPI [26,[31][32][33].…”