Detectable Substances

Theoretically, any molecules that can be ionized are detectable by IMS-based detectors. Researchers have shown that IMS detectors can be used in various applications, such as detecting explosives, illicit drugs, CWAs, and many TICs. It has also found other applications. At present, interest is greatest in instruments that can detect multiple chemicals to minimize the number of devices necessary for an operation. This focus has made IMS detectors desirable because of their nonselective but high identification power attributes. 

The idea is that it may be possible to reduce the false positive alarm rate by using more than one peak to identify a target chemical. The probabiUty of two chemicals generating a common peak is much greater than that of the two chemicals generating two or more common peaks at the same time. Therefore, using more than one peak for identification could drastically reduce the false positive alarm rate. 

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Nowadays all over the world considerable attention is focused on development of chemical sensors for the detection of various organic compounds in solutions and gas phase. One of the possible sensor types for organic compounds in solutions detection is optochemotronic sensor - device of liquid-phase optoelectronics that utilize effect of electrogenerated chemiluminescence. In order to enhance selectivity and broaden the range of detected substances the modification of working electrode of optochemotronic cell with organic films is used. Composition and deposition technique of modifying films considerably influence on electrochemical and physical processes in the sensor. 

Substances which do not exhibit such properties have to be transformed into detectable substances (denvatives) in order to evaluate the TLC separation Such reactions can be performed as universal reactions or selectively on the basis of suitable functional groups Substance-specific derivatization is practically impossible... 

This technique detects substances qualitatively and quantitatively. The chromatogram retention time is compound-specific, and peak-height indicates the concentration of pollutant in the air. Detection systems include flame ionization, thermal conductivity and electron capture. Traditionally gas chromatography is a laboratory analysis but portable versions are now available for field work. Table 9.4 lists conditions for one such portable device. 

Biocatalyst category Substrate Biocatalyst Detected substance Ref. 

List of Electrochemically Detectable Substances The following pages give tables of electrochemically detectable substances (arranged alphabetically) with native electro-activity. 

Table A-1. List of electrochemically detectable substances (continued)... 

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