to minimize protein absorption and to provide a positive electroosmotic flow. This design handled small volumes of protein solutions, which yielded mass How low can they go? Innovative technolo18 gies based on molecular characterization and spectra for < 10" mol of protein and tandem mass spectra for 10"17 mol at a imaging have succeeded in following biochemical events at the cellular and subcellar resolving power of « 60,000. The "soft" electrospray ionization generated a mullevels, especially when looking at targeted tiplicity of molecular ion charge states. compounds. However, these technologies The researchers succeeded in sepaare not as successful at finding and characterizing unknown biomolecules in a single cell. rating and collecting mass spectral data on attomole amounts of a mixture of boFred McLafferty and co-workers at Cornell vine ubiquitin, bovine carbonic anhyUniversity combined three key analytical techniques—CE, electrospray ionization with drase II (CA), and equine cytochrome c. an ultralow flow rate of 1-4 nL/min, and FT- They also analyzed a crude blood isolate MS—to develop a system capable of charac- and collected data on the ~7 amol of human CA in the sample. The human CA terizing attomole amounts of biomolecules. spectrum showed peaks for the adducIn their setup, the Cornell scientists tion of phosphate, but there was little coupled electrospray ionization directly sodium and no other proteins were deto small-bore CE. The capillary column tected. Finally, they used data from a tanwas derivatized with a silane compound dem MS study of ~ 9 amol of injected bovine CA to identify the biomolecule from a protein database. (SciTotal ion electropherogram of a mixture of 7± 2 amol of human CA from ence, 1996, a crude blood isolate (left) and the MS of the deconvoluted isotopic 273,1199regions (right). (Adapted with permission from the American Association 1202)
Attomole protein characterization
for the Advancement of Science.)
files. R C. Alkire and colleagues at the University of Illinois at Urbana-Champaign investigated using ion-selective pH microelectrodes to measure hydroxide ion conStudies of corroding surfaces require techcentrationfieldsgenerated by the electroniques that directly probe electrochemical chemical reduction of oxygen on 10- and activity and chemical composition with 25-um Pt disk electrodes. high spatial resolution. Scanning electrochemical microscopy has yielded such inDouble-barreled microelectrode sensors formation, and recently ion-selective micro- with atipdiameter of ~5 to 7 urn were electrodes have also been used as scanning mounted on a scanning system; the subsesensors to provide ion concentration proquent data were compared with predictions based on the diffusion equation. The largest difference between experimental and theoretical hydroxide concentrations was found at the disk centers, measuring pH 0.18 and pH 0.07 for the 10- and 25-um disks, respectively. The microsensors also verified the buildup of hydroxide ion that occurs on Al3Fe intermetallic inclusions that were galvanically coupled to an Hydroxide ion-concentration distribution along the aluminum alloy in 0.6 M NaCl. x-y direction of a 25-pm Pt disk measured with a (J. Electrochem. Soc. 1996, 5-pm sensor. (Adapted with permission from the 143, L174-76) Electrochemical Society.)
Support your local pH
GOVERNMENT
DOE funds user facilities Four synchrotron facilities and five other national laboratory facilities got a boost from awards announced recently by the Department of Energy. The $28.3 million in grants, which were awarded under a Presidential Science Facilities Initiative, will fund 45 projects at 22 universities and eight national laboratories. In a cost-sharing measure, the universities and other agencies will contribute an additional $29 million. The fiscal-year 1996 appropriation is $12.4 million. A large portion of the funds will be used for instrumentation and beamline upgrades of synchrotron facilities at Brookhaven National Laboratory, Stanford Synchrotron Radiation Laboratory, Lawrence Berkeley National Laboratory, and Argonne National Laboratory. Further information is available at http://www.er.doe.gov./production/ bes/bes.html.
NIST brochures A series of brochures that offer quick access to important information on NIST's standard reference materials has been prepared by the institute. Brochures are available on agriculture and food, analyzed gases, ceramics and glasses, environmental inorganics, environmental organics, ferrous and nonferrous metals, health, industrial hygiene, ion activity, optical properties, metrology, polymers, powder diffraction, semiconductors, and spectrometries. These brochures are available from the SRM Program, 204 Engineering Mechanics Bldg., NIST, Gaithersburg, MD 20899-0001; (301) 975-6776; e-mail: srminfo® enh.nist.gov.
Fundamental constants grants The NIST Precision Measurement Grants program is accepting proposals from faculty members at U.S. colleges or universities for two research grants for fiscal 1998 for determining fundamental constants, investigating related physical phenomena, or developing new fundamental measurement methods. Each grant is $50,000 for one year and may be renewed for up to two additional years. For information, contact Barry Taylor, C229 Radiation Physics Bldg., NIST, Gaithersburg, MD 208990001 (301-975-4220).
Analytical Chemistry News & Features, November 1, 1996 6 5 5 A
