Composite detectors

Analysis of nitroaromatic explosives with microchip electrophoresis using a graphite-epoxy composite detector... 

E. S. Tillman and N. S. Lewis, Mechanism of enhanced sensitivity of linear poly(ethylenimine) - carbon black composite detectors to carboxylic acid vapors , Sensors And Actuators B - Chemical 96, 329 (2003). 

On-line MS detectors for SEC offer great promise for serving simultaneously as an absolute detector, concentration-sensitive detector (i.e., total ion current), and composition detector, especially for oligomers and low-MW polymers. Successful developments in the use of matrix-assisted laser desorption ionization (MALDI) MS for high-MW polymers are extremely encouraging, and on-line MALDI MS should... 

The application of UV spectrophotometers to the analysis of styrene containing copolymers has been extensively reported in the literature. However, hypochromic effects and band shifts which result in deviations from Beer s Law have limited the use of UV detectors as mass or composition detectors in size exclusion chromatography applications. Deviations from Beer s Law for low conversion styrene-acrylonitrile copolymers in tetrahydrofuran have been experimentally investigated and compared with results previously reported in the literature. The behaviour of the extinction coefficient as a function of the copolymer composition is discussed in view of the information obtained from infrared and nuclear magnetic resonance measurements on the same polymers. As a result of this investigation, a quantitative correlation of the extinction coefficients of styrene-acrylonitrile copolymers with the length of the styrene sequences has been obtained which, in turn, allows for the use of UV spectrophotometers as sequence length detectors. 

The army has recently fielded two new systems, the FOX and the Biological Integrated Detection System (BIDS), which are discussed below. Each of these new systems integrates a variety of detectors into a mobile, crew-served system the composite detectors are vastly superior to any individual detector previously available. 

Chromatographic conditions [column, mobile phase composition, detector type or monitoring condition (e.g., wavelength) change]... 

Composite detectors are relatively new developments in gamma-ray spectroscopy. They make possible the tracking of gamma rays inside the detector. The clover detector has fom closely placed germanium crystals arranged like the leaves of a four-leaf clover. The cluster detector has... 

The possibility of constructing composite detectors which combine several individual detectors is open ended. Here, attention is limited to showing why combinations are desirable. In general, the motivation stems from the difference between analyzing small numbers of events directly as opposed to small differences in large numbers. 

If there are hydrocarbons present in the formation that is being drilled, they will show in the cuttings as oil stains, and in the mud as traces of oil or gas. The gas in the mud is continuously monitored by means of a gas detector. This is often a relatively simple device detecting the total combustible gas content. The detector can be supplemented by a gas chromatograph, which analyses the composition of the gas. 

The new instrument introduced for inspection of multi-layer structures from polymeric and composite metals and materials in air-space industry and this is acoustic flaw detector AD-64M. The principle of its operation based on impedance and free vibration methods with further spectral processing of the obtained signal. 

A mixture of methyl paraben, ethyl paraben, propyl paraben, diethyl phthalate, and butyl paraben is separated by HPLC. This experiment emphasizes the development of a mobile-phase composition capable of separating the mixture. A photodiode array detector demonstrates the coelution of the two compounds. 

In one instrument, ions produced from an atmospheric-pressure ion source can be measured. If these are molecular ions, their relative molecular mass is obtained and often their elemental compositions. Fragment ions can be produced by suitable operation of an APCI inlet to obtain a full mass spectrum for each eluting substrate. The system can be used with the effluent from an LC column or with a solution from a static solution supply. When used with an LC column, any detectors generally used with the LC instrument itself can still be included, as with a UV/visible diode array detector sited in front of the mass spectrometer inlet. 

Lead sesquioxide is used as an oxidation catalyst for carbon monoxide ia exhaust gases (44,45) (see Exhaust control), as a catalyst for the preparation of lactams (46) (see Antibiotics, P-lactams), ia the manufacture of high purity diamonds (47) (see Carbon, diamond-natural), ia fireproofing compositions for poly(ethylene terephthalate) plastics (48), ia radiation detectors for x-rays and nuclear particles (49), and ia vulcanization accelerators for neoprene mbber (50). 

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