Temperature controller for thermal ionization mass spectrometry

Abstract

We describe the use of a simple voltage stabilizer that controls the filament temperature (Tf) in the ion source of a thermal ionization mass spectrometer. The filament voltage (Vf) is measured by means of a separate pair of wires connected inside of the ion source in parallel to the wires supplying power. It has been demonstrated that Vf is directly proportional to Tf in a wide range of filament temperature. The Tf value is solely controlled by the reference voltage (Vr) that can be manually selected from a voltage divider or by means of a computer. Digital signals from the computer in the form of a series of pulses are transmitted opto-electronically and subsequently converted to analog signals. The temperature controller described here was successfully applied for analysis of potassium concentration by the isotope dilution method. Copyright © 2001 John Wiley & Sons, Ltd.