Word: chromatographer
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With failure following failure the doctors have now turned to toxicological testing. For that they use a gas chromatograph, which heats a specimen until it vaporizes. When a bright light is shone through the vapor and passed through a prism, it yields a distinctive spectrum. Yet further tests will be run with an atomic spectrometer, which searches for deadly heavy metals like mercury and lead. A shotgun approach like this, says Sencer, should disclose whether "there are chemicals you would not expect to find in human tissue." If such chemicals can be found, the detectives may have their solution...
...tiny laboratories are housed in 1-ft. cubes and weigh only 30 lbs. apiece. Each is crammed with 140,000 electronic components-including 122,000 transistors-40 thermostats, three tiny ovens, bottled radioactive gases, one pocket-sized chromatograph (used to identify the chemical component of the substance under study) and a small xenon lamp that can simulate sunshine. Costing $16.9 million each, the labs can perform three different life-detection experiments without any human help...
Golden Tube. The target of the chromatographic detective work performed by the bomb sniffer is the vapor from a chemical called ethylene glycol dinitrate (EGDN), one of the principal components of emissions given off by dynamite. With the aid of a small internal fan, the detector samples air in the vicinity of a suspect object and passes the vapors over a modern equivalent of Tsvett's limestone-a rough gold-plated copper surface that has a special affinity for EGDN. As the molecules adhere to it, their concentration increases. The special surface is then heated...
Segregated Compounds. To prepare a bacterial chromatogram, Scientists Alexander and Gould use a pure strain of bacteria, allow them to grow for several hours in a nutrient solution, then extract the metabolic products that have been excreted. These are injected into a chromatograph, where they are converted by heat into gaseous form and fed into a column containing a packing material and an organic liquid such as Carbowax-a chemical that has a different attraction for the molecules of each chemical compound. Thus every compound that passes through the column is slowed to a degree...
...varying speeds, the compounds that constitute the metabolic products are segregated. As each compound emerges-in order of its speed through the column-it is sensed by an ionization detector and recorded on a graph as a distinct peak. Within minutes, all of the compounds have passed through the chromatograph, each forming its own peak on the graph. Since the metabolic products of each strain of bacteria contain different chem ical compounds, each chromatogram forms an easily identifiable profile...