New mass spectrometry systems expand analytical horizons.
Palmer, a senior research scientist with Johnson Controls World Services Inc., Moffett Field, Calif., recently operated Hitachi's 3DQ (Three Dimensional Quadrupole) GC/MS system onboard a NASA DC-8 aircraft, flying at altitudes up to 40,000 ft, to directly monitor airborne pollutants.
The 3DQ, a 1994 R&D 100 Award winner, is an ion trap mass spectrometer that utilizes Filtered Noise Field Waveform technology to increase its sensitivity and selectivity.
This technology could allow scientists to achieve significantly lower detection limits in complex matrices such as air, sludge, mixed wastes, urine, hair, and blood by expelling nontarget ions during the ion formation period.
Applications include environmental, pharmaceutical, forensic, and general analytical analysis. The instrument also can perform multi-stage MS, assuring positive compound identification.
"There were no problems with the instrument's turbomolecular pumping system, even during heavy air turbulence," says Palmer. "Overall, the unit operated very satisfactorily, and we were able to acquire real-time data."
The 3DQ system grew out of a strategic alliance between Hitachi Instruments Inc., San Jose, Calif., and Teledyne Electronic Technologies, Mountain View, Calif., that combined engineering strengths and high-quality manufacturing expertise from both companies.
Other new MS products offer further analytical opportunities.
The DI-50 Direct Insertion Probe from Shimadzu Scientific Instruments Inc., Columbia, Md., provides liquids or solids with direct access to the benchtop GC/MS's ion chamber. With the sample in place, the probe tip can be heated to 3508 C by the instrument's temperature program.
"We recently developed an enzyme-catalyzed process to clean up water contaminated with phenolic-type compounds," says John Wiencek, a chemical engineering professor at Rutgers-The State Univ., Piscataway, N.J. "High-molecular weight oligomers are formed with these phenols, and we are studying the kinetics of the reaction."
Since the high molecular weights prohibit initial separation by GC, the resulting materials are placed on the Shimadzu probe for direct insertion to the MS unit. "This technique has helped us greatly by providing important structural information about these compounds," says Wiencek.
Finnigan MAT, San Jose, Calif., has improved its TSQ 7000 triple-stage and SSQ 7000 single-stage quadrupole mass spectrometers by including longer quadrupole mass analyzers to provide higher resolution, and adding a new hybrid turbomolecular pumping system for faster pumpdown and low baseline operating pressures.
"In addition to confirming synthetic compounds and material purity, we use our TSQ 7000 to screen natural product extractions," says Sharon Steele, a research associate with PathoGenesis, Corp., a Seattle-based drug development firm.
Steele is currently screening plant extracts and cellular substances, looking for bio-active drug leads. Additionally, she expects to soon be involved in a comprehensive drug metabolism study.
Bradley Ackermann, a mass spectrometrist at the Marion Merrell Dow Research Institute, Cincinnati, points out another important SSQ 7000 application. "Our pharmacologists are very interested in lipid profiles in the body--everything from cholesterol to fatty acids--and how they change in response to various drugs. With this GC/MS system, we now can provide these scientists with the essential analytical information they seek."
Varian Instruments, Palo Alto, Calif., has made a Saturn 4D MS/MS option available to provide its benchtop GC/MS products with enhanced sensitivity and specificity when targeting analytes in complex matrices, such as pesticide residues in food products and drug metabolites in biological fluids.
This technique is made possible through the incorporation of Varian's so-called Wave; Board into the electronics, enabling MS/MS to be performed in a single chamber of the ion trap, where ions are manipulated in the fourth dimension, time, rather than in space.
The API IIIPlus LC/MS/MS system from the Perkin-Elmer Corp., Norwalk, Conn., is an atmospheric pressure ionization (API) mass spectrometer with a host of applications.
"In biotech research today, it's important to be able to look directly at a protein and compare its mass with the mass predicted from DNA sequencing," says Kenneth Walsh, the biochemistry department chair at the Univ. of Washington, Seattle.
Actually, these mass values never quite agree, explains Walsh, because proteins undergo a variety of modifications.
"The API system helps us detect these modifications," says Walsh.
For example, a phosphate group attached to a protein can act as a control switch, regulating some biological event, says Walsh. "Since this group is now easier to identify, the system becomes a very powerful research tool in understanding the protein's function."
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|Publication:||R & D|
|Date:||Aug 1, 1994|
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