Glow Discharge Mass Spectrometer (GDMS)

The installation of a glow discharge mass spectrometer (GDMS) in September, 1999 at Denver Division of Wyoming Analytical Laboratories, Inc., Golden, Colorado, makes our laboratory one of very few laboratories equipped with both GDMS and a spark source mass spectrograph (SSMS) in the United States. We have upgraded the GDMS with the addition of a radio frequency source (rf-source), adding its capability to the normal DC source, allowing WAL to determine non-conductors or insulators in addition to the normal metals and semi-conductors. Our GDMS is a VG 9000 and has Nier-Johnson reverse ion optic geometry, and has been equipped with the new rf-source. The WAL GDMS is a state of the art solids elemental mass spectrometer for conducting and non-conducting solids.

The GDMS is capable of detection limits of 2 to 5 ppb for most elements at an analysis precision approaching 20%. The advantage of this instrument is in directly analyzing solids rather than trying to obtain aqueous solutions of refractory substances for solution multi-element analytical techniques. This gives the GDMS a huge superiority as an elemental analytical tool.

The GDMS is capable of depth profiling of conductors such as metal foils, metal surfaces, doped and undoped semi-conductors for elemental content vs. depth in the material being analyzed; sputter rates are on the order of 0.1 to 10 microns per minute, which enable a very rapid depth profiling. Pricing structure is dependent upon instrument time and number of elements profiled. Individual elemental analytes in a given matrix will be quoted upon request.

Most inorganic samples are amenable to GDMS for most of the normally occurring 80 elements. Detection limits are approximately 2 to 40 ppb, and the quantifiable concentrations are normally from 0.04 to 1000 ppm. Any concentration over 1000 ppm is normally reported as a weight percent. GDMS analysis for both trace and majors can, with standards, approach +/- 20% of the element present. The pricing structure is quoted upon detection limit basis for the GDMS, because lower detection limits (i.e. ppb range) require considerably longer instrument times.

Glow discharge mass spectrometry can be accomplished in semi-conductors, if a single pin (3mm X 20mm) or flat surface of approximately 31mm in diameter and 1mm thick is submitted. Most raw materials (such as gallium, silicon, aluminum, tungsten, tellurium and molybdenum) and finished semi-conductors (such as CdTe, GaAs, and Si) can be analyzed for trace elements directly by GDMS.

Pricing structure, is again, quoted upon detection limit basis and includes up to 30 elements for the GDMS in semi-conductors, because lower detection limits (i.e. ppb range) require considerably longer instrument times.

Further information about GDMS capabilities is available by contacting the Denver Division for a technical discussion of its advantages in your specific analytical case.