Detection of high

Provide oxygen analyzer with activation of inert gas addition on detection of high oxygen concentration... 

Provide automatic or manual introduction of quench fluid on detection of high local temperature... 

Shutdown/depressure reactor upon detection of high temperature... 

Provide isolation on detection of high flow, low pressure, or external leak... 

Metal Detection (MD) MD measures instrument responses to deposits of ferrous and nonferrous metals up to 10 to 20 ft deep. Detection of high-density deposits in shallow depths. Good inexpensive preliminary survey tool. Background conductivities greater than 40 millimhos/meter impairs results. Wet clay soils impair resluts. 

Various methods of analysis exert different thermal stress on a material (Table 6.39). Direct heating in the inlet of a mass spectrometer in order to obtain a mass spectrum of the total pyrolysate is an example of thermochemical analysis. Mass spectrometry has been used quite extensively as a means of obtaining accurate information regarding breakdown products produced upon pyrolysis of polymers. Low residence times allow detection of high masses. 

Vaidyanathan, S. Winder, C. L. Wade, S. C. Kell, D. B. Goodacre, R. Sample preparation in matrix-assisted laser desorption/ionization mass spectrometry of whole bacterial cells and the detection of high mass (>20kDa) proteins. Rapid Comm. Mass Spectrom. 2002,16,1276-1286. 

Electrospray ionization (ESI) is ideally suited as a detection technique for the online interfacing of liquid-phase separations (HPLC and CE) to MS, because it facilitates the transfer of analytes from the liquid phase of the HPLC or CE column to the gas phase of the MS. Also, it allows the detection of high molecular weight species, such as peptides. Three interface designs have been developed in the past 18 years for coupling CE with MS. The first CE-MS interface, coaxial sheath flow, was introduced by Smith and his group in 1987 (Olivares et al., 1987) and was improved upon in later work (Smith et al., 1988). Coaxial sheath flow is formed using two concentric metal capillaries, whereby the CE terminus and the makeup flow line are inserted into the... 

There are few models with automatic test capability. Testing is usually limited to hand held devices only 2 meters (7 ft.) from the detector or directly on the lens test unit. It can be ineffective if ice forms on the lens. It is sensitive to modulated emissions from hot black body sources. Most of the detectors have fixed sensitivities. The standard being under five seconds to a petroleum fire of 0.1 square meter (1.08 sq. ft.) located 20 meters (66 ft.) from the device. Response times increase as the distance increases. It cannot be used in locations where the ambient temperatures could reach up to 75 °C (167 °F). It is resistant to contaminants that could affect a UV detector. Its response is dependent on fires possessing a flicker characteristic so that detection of high pressure gas flames may be difficult. 

This method allows for the simultaneous detection of highly volatile (e.g. dioxane), volatile (e.g. polyaromatic hydrocarbons) and non-volatile (e.g. polystyrene) substances. The sensitivity of the method depends of course on the detector(s) used. In the gas chromatography-mass spectrometry mode most compounds could be readily detected in the low part-per-million range. 

In addition to the basic control loops, all processes have instrumentation that (1) sounds alarms to alert the operator to any abnormal or unsafe condition, and (2) shuts down the process if unsafe conditions are detected or equipment fails. For example, if a compressor motor overloads and the electrical control system on the motor shuts down the motor, the rest of the process will usually have to be shut down immediately. This type of instrumentation is called an interlock. It either shuts a control valve completely or drives the control valve wide open. Other examples of conditions that can interlock a process down include failure of a feed or reflux pump, detection of high pressure or temperature in a vessel, and indication of high or low liquid level in a tank or column base. Interlocks are usually achieved by pressure, mechanical, or electrical switches. They can be included in the computer software in a computer control system, but they are usually hard-wired for reliability and redundancy. 

These semiautomated systems of analyzing and characterizing small samples are vital to the natural product organic chemist and biochemist for the detection of highly active substances in extremely low concentrations in living organisms. A typical example is in the field of pheromones which includes insect sex attractants that differ quite markedly in many insects. Their concentration has often been found in the 10 —10 grange. 

Tag K, Kwong AWK, Lehmann M, Chan C, Renneberg R, Riedel K, Kimze G (2000) Fast detection of high-molecular substances in wastewater based on an enzymatic hydrolysis combined with the Arxula BOD sensor system. J Appl Chem Biotechnol 75 1080-1082... 

Domenech A, Torres FJ, Ruiz de Sola E, Alarcon J (2006) Electrochemical detection of high oxidation states of chromium(lV and V) in chromium-doped cassiterite and tin-sphene ceramic pigmenting systems. Eur J Inorg Chem 638-648. 

Wang, Y., Liu, D., Wyss, D. F. (2004) Competition STD NMR for the detection of high-affinity ligands and NMR-based screening. Magn Reson Chem 42, 485—489. 

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