Mass spectrometer

A mass spectrometer comprising:

• sample supplying means for supplying a sample solution, the sample solution including a solvent, ions, and a solute, the solute being a sample to be analyzed;
• ion converting means, disposed after the sample supplying means, for converting the ions in the sample solution into gaseous ions;
• sample ionizing means, disposed after the ion converting means, for ionizing the sample in the sample solution, thereby producing sample ions;
• mass analyzing means for analyzing masses of the sample ions produced by the sample ionizing means;
• and
• ion blocking means for preventing the gaseous ions produced by the ion converting means from reaching the sample ionizing means, thereby preventing the mass analyzing means from analyzing masses of the gaseous ions produced by the ion converting means;
• wherein the ion blocking means prevents the gaseous ions produced by the ion converting means from reaching the sample ionizing means by deflecting the gaseous ions with an electric field.