Gary A. Eiceman, New Mexico State University

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Abstract

The Analystprofiles Gary Eiceman, member of the Analytical Faculty in the Department of Chemistry & Biochemistry at New Mexico State University and one of the founding members of the International Society for Ion Mobility Spectrometry.

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Born on November 28, 1952 in Reading, Pennsylvania, USA, Gary Eiceman received his BSc (Magna Cum Laude) in Chemistry from West Chester State College, PA, in 1974 followed by a PhD in Chemistry from the University of Colorado in 1978. He spent two years as a Postdoctoral Fellow in the Department of Chemistry at the University of Waterloo in Ontario, Canada before his appointment in 1980 as an Assistant Professor in the Department of Chemistry at New Mexico State University (NMSU) in Las Cruces, New Mexico, USA. In 1984 he was promoted to Associate Professor, and in 1990 he became a full Professor at NMSU. Whilst at NMSU, he has spent sabbaticals as a Senior Research Fellow in the Research Directorate of the US Army Chemical Research Development and Engineering Center in Maryland; at University of Manchester Institute of Science and Technology (UMIST) in Manchester, UK; and more recently, at the Institut für Spektrochemie und Angewandte Spektroskopie (ISAS) in Dortmund, Germany. Since 1983, he has been a regular Visiting Lecturer at the Facultad de Ciencias Quimicas, Universidad Autónoma de Chihuahua in Mexico. He holds eight patents, is a consultant to seven industry and government agencies and is a founding member of the International Society for Ion Mobility Spectrometry. The second edition of his book “Ion Mobility Spectrometry” (published by CRC Press) is scheduled for publication this summer. The core of Dr Eiceman's research program is the exploration of ion–molecule gas phase reactions at ambient pressure in order to develop predictive models of the creation of ion mobility spectra. Secondary interests include the advancement of instrumentation and drift tube technology for IMS and selected applications in environmental venues.What early influences encouraged you to take up science?

I can recall one afternoon when a classmate invited me to a science club in Junior High School (I was about 13 years old). I had not been to the club before and that day we made castings of nickel coins using molten sulfur (tape the edge of a coin so the coin is mid-width on the tape, pour the molten sulfur into the form provided by the tape on one side of the coil, and let the sulfur cool; then pour molten sulfur in the opposite side of the coin; let cool, remove the tape, and gently pry both sulfur castings from the coin). The physical properties of sulfur, the use of crucibles, and the effects of heat on sulfur riveted my imagination. The changes in the sulfur suggested to me that there was much to discover about matter. Long before this, my sister and I as children were allowed during wintertime to throw small amounts of salt into the flames of a wood fire in the fireplace. The rich colours emitted from the salt delighted us and this topic would later reappear with discussions on atomic structure in a high school chemistry class. In that class, I was puzzled by differences in chemical reactivity and intrigued by the possibilities of synthesis. This general interest in nature had developed through walks with my father in the countryside of western Berks County in Pennsylvania. This region was then rural with large sections of undeveloped or uncultivated land. There was much for a boy to explore and discover in the streams, plants, animal life, and seasons. My interest in chemistry waned during and after freshman chemistry and returned to stay with organic chemistry and quantitative analysis in my second year at university.

The second edition of your book, Ion Mobility Spectrometry will be published this summer. How did you get involved in this area?

Though reading was a pleasure and hobby from childhood, my writing skills were weak up to and including my PhD dissertation. I saw that a postdoctoral fellowship with Professor F. W. Karasek of University of Waterloo (Canada) would be beneficial for my writing abilities and for my research interests in environmental measurements and mass spectrometry. Incidental to my interests, Prof. Karasek was also the leading academic exploring ion mobility spectrometry (IMS, then known as plasma chromatography). Virtually all the laboratory funding on IMS in his laboratory came from the Defence Research Establishment of Canada. As a US citizen, I was unable to work on these programs and so my experience with IMS at Waterloo was limited. Though I occasionally listened to discussions on IMS and assisted an MSc student in his thesis work on IMS, my interests were with separations and environmental measurements.

After arriving in Las Cruces in 1980, I understood that gas chromatography had reached maturity and I had little interest in research with other separations methods. I could not envisage a sustained university research program in separations science and began making plans to leave NMSU. At this same time, a faculty member in our College of Agriculture asked me to provide him the analytical methods to detect pesticides continuously in air after an aerial spray application to crops. His requirements included high selectivity to organophosphate compounds, parts per billion detection limits, about a one second response rate, low cost, and hand-portability. The need was immediate and alternative proposals were not acceptable to my new acquaintance; however, no methods in 1980–81 could meet these standards. All this provided a challenge for me at a time when I was looking for a challenge.

As I examined principles that might be helpful in reaching the requirements, I was drawn to gas phase ion molecule reactions and ion characterization at ambient pressure, the essentials of ion mobility spectrometry. Commercial instrumentation for IMS in the early 1980s was comparatively large and not too portable; however, these limitations seemed to me to be technical and not fundamental. In 1982, Herb Hill at Washington State University published an article on a new drift tube design with low memory effects and high speed response; this was further encouragement to continue and studies were begun in 1981 in IMS. We obtained some funding from the Department of Energy, built our first IMS drift tube, and realized that ion-molecule reactions in ambient air controlled response. This was the start of our adventures and fun with ions in gases at ambient pressure.

Plate1 Microfabricated differential mobility spectrometer undergoing development and study at NMSU. This DMS was created by R. A. Miller and E. G. Nazarov, then at NMSU in Prof. Eiceman's team and subsequently developed from funding by Draper Laboratory. This funding was intended to bring technology to a market level and SIONEX (www.sionex.com) has successfully commercialized this technology. Photo compliments of R. A. Miller.

I understand the story began in Cambridge, England, nearly a century ago.…

The systematic study of ions in air and the characterization of ions using mobility in electric fields was pioneered at the Cavendish Laboratory at Cambridge University by Thompson, Rutherford, and others.¹ Investigations by this team, their guests, and others, mostly in the UK, set the foundation for our understanding of atoms and molecules, modern analytical IMS, and even our studies today. A surprising aspect of this early work for me was how quickly the principles of gas phase ion-molecule chemistry and ion physics were explored and understood, all with comparatively primitive instrumentation. Indeed, ions in air or gases had been observed before 1900 from corona discharges, photons, radioactive particles, and X-rays; ion mobilities of ions in air had been measured by Rutherford before 1897. By 1903–05, the mathematics of the mobility of ions in gases was developed and refined to include the concept of ion-molecule interactions. Ion clusters, effects of moisture, and drift tube technology were well-developed within technology constraints by 1928.¹ Another excellent summary can be found in a 1938 monograph by A. M. Tyndall, from Bristol.² The next link to modern IMS was provided by another Englishman, J. E. Lovelock with his recognition that impurities in ambient air would alter ion chemistry in a predictable manner.³ Developments in the US resulted in drift tubes operated at ambient pressure. Parallel developments at Porton Down led eventually to the high level of engineering and technology seen at Graseby Dynamics, now Smiths Detection, in Watford. So, England is where the study of ions in air began and today is home to the leading manufacturer of modern analytical IMS instruments in the world.

“A sleeping giant awakens” has been used to describe the resurgence of interest in ion mobility research. Why did it lie dormant so long?

This may be difficult to answer. I can say that misunderstandings over the basis of response in IMS (and some complications with flows in the early generation of instruments) lead to disappointments with IMS as an analytical technique. I recall Prof. Horning, Baylor College of Medicine, Houston, Texas telling me in the early 1980s that he felt his IMS/mass spectrometer had a promising ion source (⁶³Ni) and a great detector (the mass spectrometer) but the drift tube of the ion mobility spectrometer offered him little value. Thus, he eliminated the drift tube in 1973 and introduced atmospheric pressure ionization mass spectrometry as an analytical technique.

A second part to an answer comes with the two highly successful applications of IMS: military preparedness and commercial aviation security. Both applications were initiated within government agencies and were not substantially driven by the disclosure practices used in university research teams. Consequently, commercial developments in IMS instrumentation were secondary to military or security applications and general purpose IMS analyzers were not readily available for exploration or testing by practitioners or prospective users of IMS. Commercial units were made but were refined and were priced beyond the budget of academics.

Plate2 An early configuration of a gas chromatography-DMS showing prototype drift tube and electronics.

IMS is probably best known to many of us as the technique used to screen our baggage for explosives at airports. What existing and future applications do you think are the most exciting?

I do not know of any analytical technique which is used in such numbers as IMS for on-site chemical measurements and where the analytical result has direct importance for human life or safety. Over 50,000 IMS analyzers (most of these built in the UK) have been deployed within US and UK armed forces and within NATO for chemical weapon detection. This may not have direct relevance for most in the chemical community; however, there are indirect benefits. This includes shared expertise within the instrumentation community and possible extension of such capabilities for non-military instrumentation. A good example of this is the creation by Smiths Detection of a gas chromatography/ion mobility spectrometer for monitoring air quality on the International Space Station.

Apart from wishes or hopes of mine, there are some developments within the world of IMS that may indicate future uses. I believe the miniaturization of instruments and the use of IMS/MS for exploration of bio-molecules may have a near term impact with significance for health and environment.

Tell us about some of your current projects and why you chose to research these areas?

The bulk of our current funding is for the detection of micro-organisms using pyrolysis GC with differential mobility spectrometry. The detection and identification of bacteria using chemical instrumentation has long been an interest of mine and we are enjoying the opportunity to put our full attention to these studies. The field is fairly well-developed in some facets; in other ways, we can bring new analytical capabilities to the measurement challenge with small, comparatively low cost and yet fairly capable detectors (the planar micro-fabricated differential mobility spectrometer).

We continue a low level of activity in instrument design and study. We are exploring for the first time molecular modelling and comparison of computed cross sections of ions and experimentally derived mobility coefficients. These last two projects are being made in spare time and without funding. Our work on gas phase ion chemistry is experimentally dormant though we continue to mine experimental results from the past five years. Updates can be found at http://www.chemistry.nmsu/eiceman_research/projects.html.

Plate3 Results from GC-DMS analysis of a vapor mixture of chlorcarbons. The left plot is a topographic display of retention time versus compensation voltage for the DMS. Compensation voltages are characteristic of a substance for specific field strength for the separation field. A unique advantage of the DMS is that positive and negative ions are characterized simultaneously in a single drift tube. A topographic plot for negative ions is shown in the center frame. A reconstructed gas chromatogram is shown in the right frame.

What is your finest moment?

My work is so thoroughly interwoven with post-doctoral fellows, visiting scientists to my laboratory, graduate students, former students-now colleagues, and friends in the UK, Germany and Israel that I hesitate to speak of my finest moment. All fine moments are diffuse and shared as their contributions are so significant. Moreover, there have been so many rich times of discovery and friendship I cannot choose. Some accomplishments have included the development and testing of a comprehensive model for understanding the origins of mobility spectra, the book on IMS, and our recent work with micro-fabricated differential mobility spectrometers. These are all confluences of personalities and capabilities from nations around the world resulting in fun and excitement over instrumentation and ions. There is no false humility in saying that these were team efforts with strong reliance upon others.

Whilst at NMSU you have taken sabbaticals in the UK and in Germany. In your opinion what are the differences between the US, UK and German research environments?

My times in England and Germany have been comparatively recent adventures while I have been on sabbatical leaves and during summers. I believe my experiences are too narrow a sampling of the research environments to offer any helpful comparisons. We have found warm friendships in both Manchester and Dortmund within the scientific and general communities. I have seen valuable features in each institution where I have been. In the instance of my two senior colleagues in Dortmund and Manchester, I seem to carry by comparison a low overhead in administration.

What do you think are the three most important factors for a young scientist to be successful within a cross-disciplinary multi-cultural research team?

Sense of adventure and fun: When exploration in chemistry or science is seen as an adventure and a pleasure, complications and challenges of institutions, paperwork, and cultural differences fade in significance. As I worked in Germany, I am sure I created daily an unknown word in German. This and other syntax errors, never mind cultural blunders, made for lots of laughter for all and only slightly hindered our progress in the laboratory. Here at NMSU, we enjoy both the discoveries in the laboratory and the discoveries of stories and background of our co-workers. I regularly marvel at those who leave homes and families thousands of miles away to study in the middle of the high Chihuahuan Desert.

Humility: We can speak with accuracy or clarity about such a small part of our world and humility is valuable to carry into the design of experiments and discussions on meaning of results. This is not to say we should have weak or unpersuasive arguments for our ideas, but that we should not hesitate to tell what we do not know. My goal is to allow postdoctoral fellows and graduate students as much freedom as possible in exploring an idea after some initial guidance; they may bring to a project ideas and thoughts far better than mine and we benefit from such contributions; my contribution is usually discipline in designing a course of study and general direction. Particularly when working across cultures, I have found that pride is corrosive and humility is helpful in relationships with colleagues.

Endurance: I am sorry to say we once needed more than five years to measure correctly the enthalpy of a O–H⋯Cl⁻ bond for substituted phenols and a gas phase chloride ion by collision induced dissociation with tandem mass spectrometry. We were new at such measurements and we made mistakes, often. However, we eventually completed the studies and now understand some of the variables in negative ion molecule chemistry at ambient pressure.⁴ This same endurance is needed in relationships when personalities and cultural differences require special attention.

For more on research in the Eiceman group visit http://www.chemistry.nmsu.edu/eiceman_research/

Plate4 Photograph of the Eiceman group in Fall 2003 in the plaza in front of the chemistry building at main campus in Las Cruces, NM.

References

1. J. J. Thomson; G. P. Rutherford, Conduction of Electricity Through Gases, University Press, Cambridge, 1928.
2. A. M. Tyndall, Cambridge Physical Tracts, ed. M. L. E. Oliphant and J. A. Ratcliffe, University Press, Cambridge, 1938.
3. J. E. Lovelock, in Electron Capture, ed. A. Zlatkis and C. F. Poole, Elsevier, NY, 1981, pp. 13–26.
4. G. A. Eiceman, J. A. Bergloff and K. Karpas, J. Am. Mass Spectrom., 1999, 10, 1157–1165.

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