Matrix-assisted laser sample load

Matrix assisted laser desorption ionization time-of-flight (MALDI-TOE) mass spectrometry was carried out with a PerSeptive Biosystems Voyager-DE-RP MALDl-TOF mass spectrometer. A 337-nm UV nitrogen laser producing 3-ns pulses was used in the reflectron mode. The samples were prepared by mixing 10 pi of a 0.1 M HAc solution of the sample with 20 pi of a solution of 3 mg/1 a-cyano-4-hydroxy cinnamic acid in wafer. One pi of that solution was loaded on the gold-sample plate. 

Mass spectrometry (matrix assisted laser desorption) of the cleavage products was done by dissolving the samples in 0.1% TFA then mixing 1 pi of sample solution with 1 pi internal standard solution (bovine insulin at 0.5 pmole/pl) and 1 pi saturated matrix solution (100 mM sinapinic acid). The mixture was loaded on the probe tip, air dried, and placed in the mass spectrometer. 

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