PLASMA MASS SPECTROMETER

摘要

The invention comprises a mass spectrometer wherein a sample is ionized in a plasma (14), especially an inductively-coupled or microwave-induced plasma. Ions are sampled from the plasma (14) through an orifice (16) in a sampling member (15), a second orifice (37) in a hollow tapered member (19) and a third orifice (53) in a tubular electrode (43). The hollow tapered member (19) comprises a portion (35) both externally and internally tapered with an interior included angle greater than 60 DEG , and preferably a shorter externally tapered portion (38) with an external included angle of less than 60 DEG . A tubular extraction electrode (43), preferably comprising a conical end-portion (47), is disposed within the member (19) for efficiently transmitting the ions into a mass analyzer.