Laser desorption mass spectroscopy

Thermal electrocyclizations of perhalogenated 1,3-butadienes yield perhalogenated cyclobutenes which can be solvolysed to 3,4-dihydroxy-3-cydobutene-l,2-dione ( squaric acid") and its derivatives (G. Maahs, 1966 H. Knorr, 1978 A.H. Schmidt, 1978). Double CO extrusion from fused cyclobutenediones has been used to produce cycloalkynes, e.g., benzyne from benzocyclobutenedione by irradiation in an argon matrix (O.L. Chapman, 1973) and cyc/o-Ci8, cyclo-Cn, etc. by laser desorption mass spectroscopy of appropriate precursors (see section 4.9.8). 

The first of two stays of the senior author at Iowa State University was supported by a contract between Ae United Nations Industrial Development Organization and Ae National Chemical Laboratory, administered in the United States by the Carl Duisberg Society, Inc. This work was also supported by the Engineering Research Institute of Iowa State University. The authors thank Ron Niece, Cynthia Wadsworth, Nick Strickland, and Tony Grabski of the University of Wisconsin Biotechnology Center for providing confirmation of the amino acid sequence, and Brian Chait and Ron Beavis of Rockefeller University for attempting matrix-assisted laser desorption mass spectroscopy on Ac enzyme. This article is N(X Communication No. 4950. 

Laser desorption mass spectroscopy LDMS Photons Ions... 

Tseng, K., Liu, J., Lebrilla, C. B., Collins, S. D. and Smith, R. L. Fabrication and design of open microchannels for capillary electrophoresis separations and matrix-assisted laser/desorption mass spectroscopy analysis. Proc SPIE Int Soc Opt Eng, 3606, 137, 1999. 

In 1981 Barber and Liu and coworkers [1,2] independently introduced the concept of employing matrix-assisted desorption/ionization where the absorption of the matrix is chosen to coincide with the wavelength of the employed laser to assist in the volatilization of materials. In 1988 Tanaka, Hillenkamp and coworkers [3,4] employed the laser as the energy source giving birth to matrix-assisted laser/ desorption mass spectroscopy (MALDI MS). 

Parker, J.E., Johnson, C.A.F., John, R, Smith, G.P., Herod, A.A., Stokes, B.J., Kandiyoti, R. (1993) Identification of large molecular mass material in high temperature coal tars and pitches by laser desorption mass spectroscopy. Fuel, 72,1381-1391. 

It is also common for pol3rmeric compoimds to form surface regions with compositions different from the bulk material, by selective diffusion of components. This process is termed blooming when the surface component is solid, and bleeding if it is liquid. Sulfur and fatty acid blooms can inhibit adhesion in rubber laminates (3). Laser desorption mass spectroscopy has been employed to identify surface species on vulcanized rubber (4). X-ray scattering methods for the study of polymer surfaces and interfaces have been reviewed (5). Other surface analysis techniques commonly used with polymers include attenuated total reflectance (6-8), electron microprobe (9), Auger electron spectroscopy (10), x-ray photoelectron spectroscopy (11), and scanning probe microscopic methods (12). Overviews on polymer surface analysis have been published (13,14). 

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