Tables D-1 and D-2 provide a summary review of the chemical detection and monitoring technologies and devices discussed below. The technique requires only a few nanomoles of analyte to determine characteristic information on structure and molecular weight. Mass spectrometry is useful both for determining chemical and structural information about molecules and for quantifying the concentration of atoms or molecules in a sample. A sample is introduced into the instrument, a charge is imparted to the molecules in the sample, and the resultant ions are separated by the mass analyzer component. Mass spectrometers use the difference in mass-to-charge ratio of ionized atoms or molecules to separate them from each other. Spectroscopy is the use of the absorption, emission, or scattering of electromagnetic radiation by atoms or molecules (or atomic or molecular ions) to qualitatively or quantitatively detect atoms or molecules (Scimedia, 1999). Many detection technologies are based on spectrometry, the spectrum of mass or energy in the sampling device (Barker, 1999 Scimedia, 1999). A sensor is a device that produces a measurable response to a change in a physical condition, such as temperature or thermal conductivity, or to a change in chemical concentration (Cattrall, 1997 Janata, 1989 Taylor and Shultz, 1996). Distinguishing attributes include chemical reactions that cause color changes the mass-to-charge ratio of the molecule absorption and scattering of electromagnetic energy, particularly in the infrared to microwave region reactions that cause unique emissions, such as chemiluminescence physical separation electrochemical interactions and reactions with enzymes. Separation and detection technologies make use of the attributes of a chemical that distinguish it from other chemical compounds and make it detectable by sensors (NRC, 1991).
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