Chemists Warm to Cold Fusion and Chili in Dallas
"It's incredible what an electrochemist has to do to get an invitation to an ACS meeting." B. Stanley Pons's opening remark to about 7000 chemists, crammed into a sports arena, expressed the excitement and festivity surrounding the ACS spring national meeting in Dallas.
FOCUS For many, the quickly arranged symposium on cold nuclear fusion, starring Pons, was the highlight of the meeting. From the start Pons tantalized the crowd with the apparent simplicity of his discovery. A slide of the experimental setup showed a traditional electrochemical cell clamped over a Rubbermaid dishpan. "Here's our Utah tokamak," joked Pons, alluding to the multimillion-dollar facility in Princeton, NJ, for high-temperature fusion. And, reflecting the difference in scale of the "tokamaks," Pons credited "personal accounts" for funding the novel experiments. Calorimetric measurements provid-
ed the most dramatic evidence for the Utah fusion report and the basis for claims of energy output exceeding input. After electrolyzing D2O for an extended period of time (how long remains a question), enough D + adsorbs onto a now-famous Pd cathode (Pt wire basket anode) to initiate what Pons and collaborator Martin Fleischmann label spontaneous nuclear fusion. The excess enthalpy, according to Pons, can exceed 10 W/cm 3 of electrode. Maintained for more than 120 h, the experiment produces a heat output exceeding 4 MJ/cm 3 of electrode—energy that could only come with a nuclear reaction, according to Pons. Furthermore, the energy output corresponds with something happening in the palladium electrode. Increasing
that electrode's volume or the measured overpotential (the increasingly negative shift in cathode potential as deuterium adsorbs into the electrode) produced more heat. In their initial fusion paper in the Journal of Electroanalytical Chemistry and Interfacial Electrochemistry, Pons and Fleischmann report measuring an overpotential as large as 0.8 eV with Pd. They calculate that to reproduce the same overpotential by just compressing D 2 into the electrode would require a pressure of >10 26 atm (J). Neutrons and tritium are also observed coming off the electrode. However, the low numbers of these nuclear reaction products—neutron count just threefold above background—have fueled skepticism and controversy. "Nuclear physicists are puzzled," said Harold Furth, director of Princeton's Plasma Physics Laboratory, "that the neutrons are down a billion or so." Furth, who also spoke at the symposium, pointed out that in another cold fusion experiment (muon-catalyzed fusion discovered by Brigham Young University physicist Steven Jones, who also reported low levels of cold fusion in
ANALYTICAL CHEMISTRY, VOL. 61, NO. 11, JUNE 1, 1989 · 739 A
FOCUS Pd and Ti pellets) the reactions were identical with high-temperature nuclear reactions. Theoretical chemist K. Birgitta Whaley from the University of California at Berkeley responded that the metal lattice promotes different reaction pathways. She hypothesized that deuterium nuclei overcome their mutual repulsion and fuse because of a phenomenon she called "boson screening," a reference to the statistical quantum mechanical description of nuclei like deuterium with a spin of one. Other hypotheses are being put forth, and, like high-temperature superconductivity, it may be awhile before scientists settle on one theory. According to Furth, we do not need "meditations on how this works," but chemists to perform more experiments. For those repeating the experiments, symposium participants offered some advice. Ernest Yeager of Case Western University warned that "run-of-themill Pd has voids in it." If, as many supporters believe, adsorption into the lattice holds the key, gaps or cracks in the metal could be one reason some groups are struggling to confirm the Utah observations. It was also clear that large electrodes are required. Pons and Fleischmann used Pd cathodes shaped as rods (as much as 10 cm in length and 4 mm in diameter) or sheets (8 X 8 X 0.2 cm). However, they urged caution. A 1 X 1 X 1 cm Pd cube fused and partially vaporized, destroying parts of a fume hood. Yeager also suggested trying other deuterium-adsorbing metals and— given the temperatures reported—alloys with stable lattices as cathodes. Whatever the outcome of the cold fusion experiments, Allen Bard, from the University of Texas at Austin, thanked Pons for "giving the electrochemists a very interesting few weeks and sleepless nights." According to Bard, senior researchers have flocked back into the lab, "behaving like graduate students." The cold fusion symposium was not the only place to learn about electrochemistry. This year's ACS Award for Analytical Chemistry appropriately honored Fred Anson for what longtime collaborator Robert Osteryoung called his "numerous and eclectic contributions in electrochemistry." Anson, from the California Institute of Technology, took the opportunity to discuss recent experiments exploring the binding of ferricyanide by a polyorganosiloxane cation electrolyte. The bound complex deposits on the electrode, offering Anson's group a "simple electroanalytical" technique to study the behavior of varying concentrations
of long-chain polyelectrolyte and different anions. Another view of electrochemistry was presented by the University of Cincinnati's Arthur Hubbard, this year's winner of the ACS Award in Colloid or Surface Chemistry. Hubbard talked about his work coupling techniques like low-energy electron diffraction (LEED), Auger spectroscopy, and electron energy loss spectroscopy (EELS) with surface electrochemical measurements and conversions. "We are willing," said Hubbard, "to go where the data is best gotten." For instance, Hubbard's group has used Auger spectroscopy to calculate packing densities of molecules adsorbed onto a surface. Combining data from the different techniques, they can then determine how molecules orient on a surface. As an example, nicotinic acid (3-pyridinecarboxylic acid) attaches to an electrode surface via just the pyridine nitrogen whereas picolinic acid (2-pyridinecarboxylic acid) binds through the deprotonated carboxylic oxygens and the nitrogen. Hubbard also introduced angle-dependent Auger microscopy (ADAM), a new technique for directly imaging surface structure. In another award address, Christie Enke, this year's ACS Computers in Chemistry Award recipient, outlined his efforts "aiming for an intelligent instrument." Enke, from Michigan State University, talked about MAPS (Methods for Analyzing Patterns in Spectra), the expert computer system his group developed to characterize MS and MS/MS spectra "one has never seen before." Rather than matching fragmentation patterns with a limited library of structures, MAPS, in conjunction with other programs, generates candidate structures based on spectra from a triple quadrupole mass spectrometer. The program, which operates in learning or identification modes, runs through a series of rules to convert spectra into plausible structures (2). Enke has also been exploring ways to interpret GC/MS data. Because the immense amount of data produced by repeatedly scanning the GC output "rapidly fills up a computer," his group is developing ways to selectively collect information. Cornell University's Fred McLafferty, the Frank Field and Joe Franklin Outstanding Achievement in Mass Spectroscopy awardee, also spoke about interpreting MS spectra. McLafferty compared the single dimension of analysis from weighing a precipitate or determining an MS parent peak with the flood of information from high-res-
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FOCUS olution MS and the newer multiple and hyphenated MS techniques. "We need more and more information as the mol ecule gets larger," said McLafferty. However, "if you are going to get 106 pieces of data, it is not certain that it will distinguish isomers. We have never shown these problems to outsiders," McLafferty admitted. To illustrate the point, McLafferty presented a host of spectra showing different fragmenta tion patterns for the same molecule run under slightly different conditions, or slight changes in structure (e.g., a shift of a double bond) producing very dis similar patterns. Fortunately, solutions to these prob lems are now appearing. New tech niques such as tandem MS, ion-mole cule reactions, or photodissociation of fer sophisticated ways to acquire mass data on molecules as large as 100,000 daltons. One of the new MS techniques was discussed by the winner of the ACS Award for Nuclear Chemistry. Ronald Macfarlane, from Texas A & M Univer sity, recounted how 262Cf particle desorption mass spectrometry (PDMS) evolved from a technique to identify short-lived radionuclides produced from nuclear reactions. Spectra from time-of-flight MS revealed a persistent impurity peak in the radionuclide ex periments. Macfarlane determined that the impurity came from a surface collecting radioactive atoms. In tracking down the impurity, Mac farlane discovered that β decay using a source like 252Cf could desorb surface molecules under high vacuum from a matrix. More importantly, the mole cules were ejected with low internal ex citation, allowing Macfarlane to gener ate molecular ions for large, nonvola tile, and fragile molecules such as proteins. Although other desorption techniques, such as fast atom bom bardment, have been developed, Mac farlane says t h a t 252 Cf-PDMS " r e mains as one of the most powerful MS methods, particularly for the analysis of proteins up to 35,000 daltons." Another approach for analyzing large molecules was presented by Pur due University's Fred Régnier, winner of the ACS Award in Chromatography. "In proteins with as many as 500 amino acids, what are the discrimination limits?" asked Régnier. This is an important question for biotechnology firms looking for ways to assess errors—some quite small—that are regularly found in proteins manufactured by genetically engineered organisms. Regnier's group has been investigating how well techniques such as ionexchange and reversed-phase chromatography distinguish these errant pro-
teins. T h e protein's bulky threedimensional shape limits the number of molecular sites that can interact with the chromatographic sorbent. Yet Regnier's group has succeeded in separating proteins that vary by only a methylene group. They find that the interacting site— whether a charged amino acid or a histidine residue—is affected by its local microenvironment (3). For instance, variations in the amino acid that sits 15 À from a histidine on the protein serine protease subtilisin produced significant changes in retention time on an immobilized metal affinity column. In total, the microenvironment covered ~600 À2 of protein surface. Régnier points out that chromatography could deliver in minutes quality assurance information that now takes a full day to collect. By obtaining timely information, manufacturers could correct production problems in midstream. Another problem of the biotechnology industry was tackled by University of Maryland microbiologist Rita Colwell. Speaking at the Division of Environmental Chemistry, Colwell challenged chemists to find new ways to track genetically altered organisms released into the environment, warning that "recall is not possible." Anything released "must be detectable," she said. Analysis is required to answer questions about the organism's persistence in the environment and its gene transferability from altered to wild forms. Pathogenicity, according to Colwell, is "highly unlikely," especially because modified organisms lack the genes to invade a host. Measurements must detect a single gene or 1-2 cells in a given volume. For example, the recently developed polymerase chain reaction (PCR), functioning like a Xerox machine to reproduce multiple copies of a DNA fragment, allows the detection of one gene copy per gram of soil. The full meeting schedule left little time to explore Dallas, so the city came to the meeting. In honor of National Chemistry Week, ACS staged its first chili cook-off inside the city's elegantly restored Union Train Station. Cowboy bandanas, a country western band, and entertainment by local sections added extra zest to the taste testing. From cold fusion to chili, the meeting offered a week of Texas-sized events. Alan R. Newman References (1) Fleischmann, M.; Pons, S.; Hawkins, J. Electroanal. Chem. 1989,261, 301-08. (2) Enke, C. G.; Wade, A. P.; Palmer, P. T.; Hart, K. J. Anal. Chem. 1987,59,1363A1371A. (3) Régnier, F. Science 1987,238,319-23.
