1P-39 PDF
高圧過熱エレクトロスプレーイオン化法
Heating the ESI ion source is a common practice, either to improve the desolvation of charged droplet, or to induce the conformation change of protein under different thermal activation. However, for API ESI, the heating of sample solution under atmospheric pressure is limited by the standard boiling point of the solution.
Here, we report a new ion ESI ion source, in which the solution flowing through the emitter capillary was heated beyond its standard boiling point under super atmospheric pressure. The operation of the present ion source was based on our previous high pressure ESI sources where the gas pressure in the ion source chamber was pressurized with air or nitrogen to more than 1 atm. Conducting the ESI under a high pressure condition is beneficial for the aqueous solution because the corona or arc discharge that disturbs the electrospray can be effectively eliminated. Much like the concept of the pressure cooker, the boiling point of liquid increases when it is under pressure and that allows the temperature of the solution to be further increased beyond its standard boiling point. For example, the solvent (water) under 1 atm is completely vaporized when the emitter temperature exceeds 100 C. However, when the ion source is pressurized to 11 atm, the electrospray remains stable even at 180 C.