Abstract
Electrospray sample deposition was explored for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). In this method, nanoliter volumes of matrix/analyte mixture were electrosprayed from a high voltage biased (1-2 kV) fused-silica capillary onto a grounded MALDI plate mounted 100-500 μm from the capillary outlet. Electrospray deposition with these conditions produced sample spots 200-300 μm in diameter thus matching the laser spot size. Varying spray voltage and distance resulted in different crystal sizes and volatilization rates for α-cyano-4-hydroxycinnamic acid matrix. Best results were obtained when the sample was deposited as wet droplets as opposed to deposition as dried solid. Under 'wet-spray' conditions, 2-4 μm diameter crystals were formed and detection limits for several neuropeptides were 0.7-25 amol. Samples could be pre-concentrated on the plate by spraying continuously and allowing sample to evaporate in a small spot. Sample volumes as large as 580 nL were deposited yielding a detection limit of 35 pM for neurotensin 1-11. Electrospray sample deposition yielded similar results when using atmospheric pressure-MALDI coupled with a quadrupole ion trap mass spectrometer, except that the sensitivity was ∼seven-fold worse.
Original language | English (US) |
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Pages (from-to) | 1193-1200 |
Number of pages | 8 |
Journal | Rapid Communications in Mass Spectrometry |
Volume | 18 |
Issue number | 11 |
DOIs | |
State | Published - 2004 |
ASJC Scopus subject areas
- Analytical Chemistry
- Spectroscopy
- Organic Chemistry