news
bly intermediates or mass spectrometricderived species.” More Q-TOF work is ahead.
Searching for new ionization sources There was a lot of talk about new ionization sources at the 15th International Mass Spectrometry Conference in August. That shouldn’t come as too much of a surprise, based on the growing popularity of LC/MS. At a workshop on new trends in instrumentation for MS, Andries Bruins of the University of Groningen (The Netherlands) emphasized the need for new ionization sources for LC/MS, especially for the analysis of apolar compounds. Atmospheric pressure ionization (API)based sources began gaining popularity several years ago, when commercial mass spectrometers capable of switching between electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) became available. Today, they are the most widely used LC/MS interfaces.
ESI involves ionizing molecules in the liquid phase, whereas APCI is based on ionization in the gas phase. In APCI, the sample is evaporated and reacted with ions generated by a corona discharge electrode. Moderately polar samples with low ionization energies can be ionized by electron transfer reactions in the APCI source. Although APCI can be used for less polar molecules, there is still a need for new ionization sources to handle nonpolar compounds, said Bruins. In particular, drug companies are looking for ways to analyze steroids and birth control pills, he said. Atmospheric pressure photoionization (APPI) has the potential to help with less polar compounds. APPI differs from APCI, in that instead of using a corona discharge, 10.0 eV photons are used to initiate sample ionization. According to Bruins, either radical cations or protonated molecules can be formed in APPI; however, the generation of protonated molecules has been found to be more efficient.
APPI has the ability to ionize moderately polar to polar compounds, with 5–10 times the sensitivity of APCI. Bruins showed that APPI was 5 times more sensitive than APCI in an LC/ MS/MS assay of testosterone in bodily fluids. Although it will likely be useful to pharmaceutical companies, APPI is not yet suitable for nonpolar compounds. “We still need more ionization sources for LC/MS,” concluded Bruins. A member of the audience representing a pharmaceutical company suggested an alternative solution. “Forgo the use of LC. We need to change the mindset of pharmaceutical companies to use other separations, such as GC.” In contrast, a few leading mass spectrometrists advocated eliminating separations altogether and injecting samples directly into a mass spectrometer. There are many paths pharmaceutical companies can take, but as long as LC/MS continues growing at double-digit growth rates, we will likely continue seeing the development of new ionization sources.
University, and Roland Hirsch of the U. S. Department of Energy will serve as councilors; Michelle Buchannan of Oak Ridge National Laboratory, Mark Wightman of the University of North Carolina–Chapel Hill, Karen B. Sentell of Ciba Vision, and Thea Barbarakis of Bayer will serve as alternate councilors, respectively.
scopy and Microinstrumentation Group in the Chemical and Analytical Sciences Division at Oak Ridge National Laboratory, received his Ph.D. from Indiana University. Ramsey’s research interests include microfabricated chemical instrumentation, ultrasensitive laser-based detection techniques, nonlinear spectroscopies, and real-time chemical characterization of aerosol particles. D. Jed Harrison received his Ph.D. from the Massachusetts Institute of Technology. Harrison’s research interests include the application of microfabrication methods and micromachining technologies to analytical systems and chemical sensors. He is currently the chair of the Micro-TAS steering committee.
PEOPLE 2000–01 DAC Officers Bruce Chase (top photo) of DuPont began a one-year term as chair of the ACS Division of Analytical Chemistry. Catherine Fenselau (bottom photo) will replace Chase as chair-elect. John Richardson of Shippensburg University will remain the division secretary, and Carolyn Ribes will remain the treasurer. Charles Wilkins of the University of Arkansas, Sally Stafford of HewlettPackard, Isiah Warner of Louisiana State
CE Award J. Michael Ramsey and D. Jed Harrison jointly received the Frederick Conference on Capillary Electrophoresis Award for outstanding achievements in the field of CE. The awards were given at the 11th Annual Conference, October 16–18. J. Michael Ramsey, corporate research fellow and leader of the Laser Spectro-
N O V E M B E R 1 , 2 0 0 0 / A N A LY T I C A L C H E M I S T R Y
685 A
