A fragmentation study of the Rhodamine 610 cation using visible-laser desorption ionization
ABSTRACT The fragmentation of a potential visible matrix-assisted laser desorption ionization: Rhodamine 610 was studied under 532 nm visible irradiation, as a function of anion counter ion. It was found that at a fixed fluence, the chloride salt produced fewer fragments than those formed with ClO(4)(-) or BF(4)(-). Evidence presented suggests that the degree of fragmentation is inversely proportional to the strength of the contact ion pair in the solid state; that is, more energy is deposited into the radical cation which can lead to fragmentation when less energy is required to separate the ion pair. Similar results were found for salts of Rhodamine 6G.
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ABSTRACT: An atmospheric pressure (AP) visible-wavelength MALDI source was developed and coupled to a quadrupole time-of-flight (Q-TOF) mass spectrometer. This instrument employed a pulsed laser emitting light at a wavelength of 532 nm to desorb and ionize samples such as dyes, oligosaccharides, peptides, and synthetic polymers at atmospheric pressure. Ions formed were analyzed by the Q-TOF in both MS and tandem MS (MS/MS) modes. Several visible-wavelength absorbing dyes were successfully utilized and studied as matrices. Among these dyes, nuclear fast red (NFR), rhodamine B isothiocyanate (RITC), and 5(6)-carboxytetramethyl-rhodamine N-succinimidyl ester (TAMRA, SE) are reported as effective visible-wavelength MALDI-MS matrices for the first time. This report demonstrates applicability of visible-wavelength AP MALDI-MS and AP MALDI MS/MS to the detection and structural analysis of dye molecules, biomolecules, and synthetic polymers.International Journal of Mass Spectrometry 04/2012; 315:66–73. DOI:10.1016/j.ijms.2012.03.002 · 2.23 Impact Factor