Abstract
A preliminary study on the laser spray and electrospray was made using an orthogonal time-of-flight mass spectrometer. Explosive vaporization and mist formation occurred when an aqueous solution effusing out from the tip of the stainless steel capillary was irradiated from the opposite side of the capillary by a 10.6 μm infrared laser. Little ion signals could be detected when the plume was sampled through the ion sampling orifice. When a high voltage (∼3 kV) was applied to the stainless steel capillary, strong ion signals appeared. The ion intensities were found to be more than one order of magnitude stronger than those obtained by the conventional electrospray for aqueous solutions of arginine and lysozyme. The present method is regarded as the electric-field assisted MALDI in which the LC solvents (water etc.) act as liquid matrices. The laser spray will be a versatile method for the biological mass spectrometry because this method is compatible with the natural solvent, water.
