A gas chromatography-quartz crystal microbalance for speciation of sulfur compounds in landfill gas.
A new method, based on separation with gas chromatography and detection with a quartz crystal microbalance, was used for the quantification of ethane-1-thiol, propane-1-thiol, ethyl methyl sulfide, propane-2-thiol, butane-2-thiol and butane-1-thiol. The analytical error, the analysis time and the general analytical performance are identical for gas chromatography-mass spectrometry (GC-MS) and gas chromatography-quartz crystal microbalance (GC-QCM). However, the GC-QCM method constitutes a low cost alternative to GC-MS for monitoring individual sulfur compounds in landfill gas. It is an easily assembled apparatus made with an injection device, a furnace, a column, a crystal cell and a quartz crystal.
Acoustic methods of detection in gas chromatography.
A brief review of the use of acoustic detection methods in GC is presented. While a number of methods (some quite similar) have been developed for use as gas-phase sensors in various applications, this article focuses specifically on those techniques that have been used to detect analytes following their separation by GC. Overall, a number of "active" acoustic methods (which measure analytes through their interaction with a controlled external acoustic wave source) were reportedly used as GC detectors. These include ultrasonic, thickness shear mode, surface acoustic wave (SAW), and flexural plate wave methods. Conversely, "passive" acoustic methods (those that produce an acoustic signal through some chemical reaction with the analyte) have also been used as GC detectors. These include photoacoustic and acoustic flame methods of detection. Of the two major classifications, reports of active methods are far more prevalent. In particular, the usage of SAW techniques with GC is an area of research that has seen accelerated growth in recent years.
Linguistic experts as semantic tour guides
This article examines the phenomenon of linguists testifying as experts on meaning in legal disputes over the interpretation of statutes, contracts, transcripts of tape-recorded conversations, and other important legal texts before courts in the USA. It concludes that there is an important role for linguists in such cases -- the role of the tour guide. It suggests that judges need not be concerned about linguists usurping the traditional roles of the judge and the jury as ultimate interpreters provided that the linguist's testimony is appropriately circumscribed.