news Isotope trap
Signal of a single trapped 85Kr atom. (Adapted with permission. Copyright 1999 American Association for the Advancement of Science.)
There is much to be learned from a few carefully measured atoms. Z.-T. Lu and colleagues at Argonne National Laboratory introduce atom trap trace analysis (ATTA), a new method for ultrasensitive isotope trace analysis. ATTA, which is based on the laser manipulation of neutral atoms, offers isotope measurements that are free of interference from other isotopes. Therefore, the
3, 2, 1—Blast off! In preparation for the European Space Agency’s Rosetta mission, scheduled for launch in 2003, C. Szopa and co-workers at Université Paris (France) and the Max-Planck-Institut für Aeronomie (Germany) have been contributing to the development of a pyrolysis GC/MS system, which will be used in the cometary sampling and composition (COSAC) experiment. The COSAC experiment is expected to shed light on the origin of the solar system and life on Earth through the in situ analysis of cometary nuclei. The GC subsystem of the COSAC instrument is designed to be used as either a stand-alone gas chromatograph or coupled to a time-of-flight MS system. It contains eight columns, four of which can be operated simultaneously and all of which share a common injector. Detection is performed by miniaturized thermal conductivity detectors. Five of the columns are dedicated to chemical composition analysis, whereas the other three are for chiral analysis. Because the columns will be used under harsh conditions and subjected to unknown and unusual samples, work is currently under way to evaluate the robustness of various stationary phases. The French and German researchers investigated a series of dimethylpolysiloxane (DMPS) stationary phases of increasing percentages (0, 5, 20, 35, and 65) of diphenyl (DP) substituted groups for use in the GC subsystem. DP–DMPS stationary phases were chosen because of the wide range of compounds they are capable of separating and because of their high stability. Weight and gas consumption restrictions imposed on the COSAC experiment limited column lengths to ~10 m and inner diameters to the 0.15–0.25 mm range. Using a four-point experimental calibration in conjunction with modeling software, the researchers successfully predicted retention times for multicomponent chromatograms with
