Wavelength Dependence of Soft Infrared Laser Desorption and Ionization

Little, Mark W.; Laboy, Jorge L.; Murray, Kermit K.

doi:10.1021/jp063154v

Cited by 41 publications

(37 citation statements)

References 24 publications

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“…At IR laser fluences greater than 15 kJ/m 2 , the tissue was completely ablated. The presence of a lower energy threshold is consistent with the previous finding on thin insulin film IR ablation [41]. The loss of signal at high fluence can be explained either by large particle production or by thermal degradation of the biomolecules.…”

Section: Resultssupporting

confidence: 91%

Laser Ablation with Vacuum Capture for MALDI Mass Spectrometry of Tissue

Donnarumma

Cao

Murray

2015

J. Am. Soc. Mass Spectrom.

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Abstract. We have developed a laser ablation sampling technique for matrix-assisted laser desorption ionization (MALDI) mass spectrometry and tandem mass spectrometry (MS/MS) analyses of in-situ digested tissue proteins. Infrared laser ablation was used to remove biomolecules from tissue sections for collection by vacuum capture and analysis by MALDI. Ablation and transfer of compounds from tissue removes biomolecules from the tissue and allows further analysis of the collected material to facilitate their identification. Laser ablated material was captured in a vacuum aspirated pipette-tip packed with C18 stationary phase and the captured material was dissolved, eluted, and analyzed by MALDI. Rat brain and lung tissue sections 10 μm thick were processed by in-situ trypsin digestion after lipid and salt removal. The tryptic peptides were ablated with a focused mid-infrared laser, vacuum captured, and eluted with an acetonitrile/ water mixture. Eluted components were deposited on a MALDI target and mixed with matrix for mass spectrometry analysis. Initial experiments were conducted with peptide and protein standards for evaluation of transfer efficiency: a transfer efficiency of 16% was obtained using seven different standards. Laser ablation vacuum capture was applied to freshly digested tissue sections and compared with sections processed with conventional MALDI imaging. A greater signal intensity and lower background was observed in comparison with the conventional MALDI analysis. Tandem time-of-flight MALDI mass spectrometry was used for compound identification in the tissue.

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Section: Resultssupporting

confidence: 91%

Laser Ablation with Vacuum Capture for MALDI Mass Spectrometry of Tissue

Donnarumma

Cao

Murray

2015

J. Am. Soc. Mass Spectrom.

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“…The wavelength was set at 2.94 μm to overlap with the OH stretch absorption of the analyte [28] and the repetition rate was 2 Hz. The laser was directed at the target at a 45º angle and was focused onto the target with a 250 mm focal length lens and the spot size of the laser beam at the capillary tip was approximately 200 μm×300 μm as determined with laser burn paper.…”

Section: Methodsmentioning

confidence: 99%

Infrared Laser Ablation Sample Transfer for MALDI and Electrospray

Park

Murray

2011

J. Am. Soc. Mass Spectrom.

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We have used an infrared laser to ablate materials under ambient conditions that were captured in solvent droplets. The droplets were either deposited on a MALDI target for off-line analysis by MALDI time-of-flight mass spectrometry or flow-injected into a nanoelectrospray source of an ion trap mass spectrometer. An infrared optical parametric oscillator (OPO) laser system at 2.94 μm wavelength and approximately 1 mJ pulse energy was focused onto samples for ablation at atmospheric pressure. The ablated material was captured in a solvent droplet 1-2 mm in diameter that was suspended from a silica capillary a few millimeters above the sample target. Once the sample was transferred to the droplet by ablation, the droplet was deposited on a MALDI target. A saturated matrix solution was added to the deposited sample, or in some cases, the suspended capture droplet contained the matrix. Peptide and protein standards were used to assess the effects of the number of IR laser ablation shots, sample to droplet distance, capture droplet size, droplet solvent, and laser pulse energy. Droplet collected samples were also injected into a nanoelectrospray source of an ion trap mass spectrometer with a 500 nL injection loop. It is estimated that pmol quantities of material were transferred to the droplet with an efficiency of approximately 1%. The direct analysis of biological fluids for off-line MALDI and electrospray was demonstrated with blood, milk, and egg. The implications of this IR ablation sample transfer approach for ambient imaging are discussed.

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“…Since plume velocities of the order of 10 5 cm s -1 were measured in this work, it should be possible, after 10 -20 µs has elapsed, to achieve a target that is predominantly analyte. Alternatively, a matrix free desorption technique [11] using infrared laser radiation may be employed in which a surface such as graphite or silicon absorbs the laser energy leading to desorption of the molecules.…”

Section: Introductionmentioning

confidence: 99%

Formation of gas phase macromolecular targets by laser desorption from surfaces

Merrigan¹,

Hunniford²,

Timson³

et al. 2008

J. Phys.: Conf. Ser.

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Abstract. To study biomolecular fragmentation induced by low energy ions, electrons, photons and radicals requires the production of a characterised gas phase target. Previous studies have used thermally evaporated DNA or RNA bases however this technique cannot be applied to a wide range of biomolecules because of fragmentation or decomposition. The technique described here involves the use of IR laser desorption for the production of the target in conjunction with time of flight mass spectrometry for analysis of molecular fragmentation. Characterisation of the targets will be carried out by fluorescent dye tagging and laser induced fluorescence imaging of the target spatial density profiles.

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Wavelength Dependence of Soft Infrared Laser Desorption and Ionization

Cited by 41 publications

References 24 publications

Laser Ablation with Vacuum Capture for MALDI Mass Spectrometry of Tissue

Laser Ablation with Vacuum Capture for MALDI Mass Spectrometry of Tissue

Infrared Laser Ablation Sample Transfer for MALDI and Electrospray

Formation of gas phase macromolecular targets by laser desorption from surfaces

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