|
Original Date: 11/03/1996
Revision Date: 01/18/2007
Best Practice : Mass Spectrometer Improvements
Mass spectrometry remains one of the most widely-used analytical techniques. Oak Ridge National Laboratory (ORNL) has maintained a long history in fundamental and applied mass spectrometry since the 1940s. Recognized as a world leader, ORNL continues to improve upon this technology.
Every two to four weeks, gas chromatograph/mass spectrometer (GC/MS) systems are typically calibrated by disassembling and cleaning the system. In addition, many organic compounds are subjected to thermal and catalytic breakdown in conventional GC/MS systems. ORNL designed a double-oven injection system for use with GC/MS systems which reduces the amount of calibrating and cleaning required by the system. The new design also operates the ion source at less than 80°C which prevents thermal and catalytic breakdowns and increases detection limits by 10 to 100-fold. Installed over five years ago, ORNL’s system regularly scores 100% on the initial attempt against the EPA’s Contract Laboratory Practices, Performance Evaluation Testing, and Proficiency Analytical Testing calibration test samples. In addition, the system can be run for 2,000 to 3,000 hours (six months to a year) without requiring cleaning which decreases non-productive labor and instrument downtime.
To prevent the detection of drugs, illegal drug users devise ways of adulterating their body fluids. ORNL developed mass spectrometers which can defeat these adulterations by analyzing body fluids through a direct sampling method. This method reduces analysis turnaround time from five hours (or more) to less than three minutes. Although ORNL concentrated on the detection of THC-COOH (marijuana) in urine samples, future developments will allow other types of drugs to be detected. In addition, ORNL uses solid phase membrane extraction (SPME) for the direct extraction of organic compounds (contaminants, explosives, drugs, organic solvents) from the air as well as body fluids. SPME, in combination with GC/MS, creates a very powerful and fast analytic technique.
Other technology developed by ORNL include:
Ion trap mass spectrometers to rapidly analyze water, soil, and airborne contaminants.
Small and micro mass spectrometers to study exhaust manifold gases from diesel and gasoline engines. Estimated total system cost is less than $5,000.
Air-sampling mass spectrometers with a Townsend Discharge chemical ionization source which is not affected by O2 and H2O.
Sensor mass spectrometers which use low voltage electron impact, instead of an inlet separation device, to directly monitor air.
Quadrupole and magnetic-sector, mass-analyzer mass spectrometers with ion sources that function in the 10-3 Torr region and produce excellent quantitative results between 10-8 and 10-3 Torr.
For more information see the
Point of Contact for this survey.
|
