Use of region II of the a/q stability diagram for fast scanning of a linear quadrupole mass spectrometer

• Published in: Journal of the American Society for Mass Spectrometry Vol. 8; no. 5; pp. 539 - 544
• Main Authors: Grimm, Casey C., Clawson, Richard, Short, Robert T.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01-05-1997; Elsevier Science; Springer Nature B.V
• Subjects: Aliasing; Exact sciences and technology; Gas chromatography; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Ionization; Ions; Mass spectrometers and related techniques; Mass spectrometry; Physics; Power supplies; Quadrupoles; Stability; Time constant; Toluene; Gas chromatography; Peak resolution; Coupled method; Spectral line profile; Mass spectroscopy; Experimental study; Quadrupole spectrometer
• ISSN: 1044-0305; 1879-1123
• DOI: 10.1016/S1044-0305(97)00006-8

For evaluation as a detector for high-speed gas chromatography, a linear quadrupole mass spectrometer was operated in rf only mode by using Region II (
a = 0; 7.514 <
q < 7.580) of the Mathieu
a/q stability diagram. The available power supply and the diameter of the quadrupole rods of the mass spectrometer placed an upper mass limit of ~
m/z 93. Scan rates of 1000 scans/s were obtained with mass spectral peaks resolved over an 80-u range The
m/z 91 and 92 ions produced from the electron ionization of toluene are resolved with an
R
1/2 of 135. A potential difference between the source and the quadruple mass filter of up to 1000 V was used to accelerate ions into the quadrupole. Broadening of mass-to-charge ratio peaks results from the time constant of the signal amplification rather than the small number of rf cycles the ions experience. The expected loss of sensitivity relative to Region I is observed, and the problem of mass aliasing is discussed.