| 摘要 |
PURPOSE:To prevent any blocking of the fine hole of a counter electrode as well as any stagnation of the surplus gas by curving the pointed end of a corona-discharge needle electrode in ?-like form and causing the counter electrode to have a conical skimmer-like shape. CONSTITUTION:When making an ion source for an atmospheric pressure ionization mass spectrometer by using a corona discharge needle electrode 7 and a counter electrode 3 having a fine hole 4, an end portion (of about 3mm. length) of the needle electrode 7 is curved in ?-like form so that the pointed end is perpendicular to the counter electrode 4. In addition, the counter electrode 3 has a skimmer-like shape (the slope of the cone is adjusted to around 30 deg.). Accordingly, even when the sample contained in the solution is introduced after being atomized, large particles of the vapor once bump against the needle electrode 7 before being divided into small particles. Consequently, blocking of the hole 4 is suppressed and it is possible for the surplus gas which has not been sampled to escape outside the outlet 2 after traveling along the wall of the counter electrode 3. |
