tradeoff between sensitivity and fiber length, but there are tricks to overcome the problems. Hieftje explains: "All we have to do is have the fiber go in a continuous loop back to the instrument. We send a pulse alternately into both ends of the fiberr These could actually be at opposite ends of a long linear fiber. Because we are sending pulses into both ends of thefiberin an alternating fashion, we actually need to collect the signal from about only half the fiber at a time. With modifications, this technology could be used in very long fibers." The dependence on the evanescent wave has positive and negative ramifications on the sensor. "On the one hand, it limits the range of species that you can detect to those that have a reasonable diffusion coefficient in the polysiloxane," says Hieftje. "However, you don't have to worry about the interferences that would plague conventional sensors. In some sensing applications, we worry very much about ionic species. Polysiloxane, being a very hydrophobic material, completely excludes ionic species only neutral things get in [the sensing region]. Interferences that would otherwise be caused by ionic species are completely absent in this kind of sensor." The continuous sensor has several advantages over a comparable array of point sensors. An important advantage is cost. "If we want to have a few hundred meters of sensing fiber, all we have to do is soak the few hundred meters on its original spool— first in the swelling solvent then in the reagent bath," says Hieftje. "The reagent is incorporated in the wholefiber.The whole process is done at once rather than having to make 50 or 100 sensors." A second advantage is that there's no need to multiplex the signal from many sensors. The third advantage of the continuous sensor is just that—it provides truly continuous sensing. Hieftje cites a chemical plant and hazardous waste site as examples of where that characteristic might be valuable. "You could build afiberthat would go all the way around the chemical plant that sets off an alarm whenever the toxic agent happens to be sensed. We know exactly where the material exists." The future of the OTOF sensors research is uncertain. "We actually bootlegged this whole thing," says Hieftje. "Radislav [Potyrailo] got interested in it, and so did I. We did all this work without any funding. The next step is going to be dependent on which agency funds us first." Celia Henry
NEWS FROM PITTCON The staff ofAnalytical Chemistry reports from new Orleans, LA.
Beckman hopes to create protocol standard Tired of waiting for the instrument industry to agree on protocols for communication between instruments? So—it appears—is Beckman Instruments, whose Sagian division is offering to make the programming code for its new ROME (routed open modular environment) software available to interested instrument or software suppliers and system integrators—in effect creating a de facto standard. ROME allows software modules for the specific functions of laboratory automation systems to be coordinated through messages sent via a router. Through a "system registry", the connections can be deffned wiihout reprogramming. Beckman hopes that ROME will become a standard architecture for lab automation systems. Speaking at a press conference at Pittcon Chris Neary strategic marketing manager for biorobotics said that Beckman hopes to release the module development kit by this summer
sored by the National Science Foundation and NIST, was scheduled for the weekend following Pittcon and preceding the meeting of the American Institute of Chemical Engineers, to promote interactions between the two groups.
Big plans for 50th Next year marks the 50th year of Pittcon, and organizers are planning a major celebration at the meeting in Orlando, FL According to Tom Conti, next year's Piitcon president, the exhibit of "antique" instruments first displayed at the 45th annual meeting in Chicago will make a return appearance. .n addition, there are tentative plans for a halfday session looking back at the history of analytical chemistry and Pittcon. Finally, Pittcon has reserved Disney World on Wednesday evening for convention goers. Anyone with a Pittcon badge wiil get into the famed park for free, and family members will be charged a reduced price. Dates for next year's meeting are March 7-12.
NEWS FROM ABRF ’98
Building a roadmap for industry How to make chemical measurement more powerful and more useful? These are the questions being asked by one of the six task groups that are working toward the implementation of the recommendations in "Technology Vision 2020: The U.S. Chemical Industry", a report released in 1996. Members of the task group on chemical measurements presented some of the group's findings at a workshop at Pittcon. In the report, the committee recognized six broad areas that industry, academia, and government collaboratively need to emphasize for the U.S. chemical industry to maintain an advantage. Under the broad category of "enabling technologies", they recognized the need for advances in chemical measurements, which the task group has further divided into seven specific "technology bundles", including measurements for process control, chemical imaging, species-specific analyses, and interface characterization. In addition, a meeting held the weekend after Pittcon focused on the technology bundle dealing with process measurement and control. The meeting, jointly spon-
Celia Henry reports from San Diego, CA.
Edman and MS go hand in hand A scan of the research literature might lead one to believe that sequencing of proteins by Edman degradation is a relic of the past. However, results from a study by die protein sequencing committee of the Association of Biomolecular Resource Facilities show that a gulf exists between the state of the art and routine protein analysis. Fifty-three facilities participated in the blind study, in which they were asked to determine die amino acid sequence of a 2.8 pmol sample of 17--esidue pepttde. Only six facilities attempted to use MS as a sequencing metiiod (postsource decay or MS/ MS), and only one of those used MS as the sole sequencing technique. The most successful facilities used a combination of Edman sequencing and mass spectrometric determination of the peptide mass. The committee also found a negative correlation between the age of an automated protein sequencer and the number of residues a facility was able to assign accurately.
Analytical Chemistry News & Features, May 1, 1998 3 1 1 A
