Carbonate sensor

S. Makarychev-Mikhailov, A. Legin, J. Mortensen, S. Levitchev, and Y. VLASOV, Potentiometric and theoretical studies of the carbonate sensors based on 3-bromo-4-hexyl-5-nitrotrifluoroacetophenone. Analyst 129, 213-218 (2004). 

Because of their high heat capacity, only few of the thermometers described in Chapter 9 can be used as sensors for detectors. Resistance (carbon) sensors were used for the first time in a cryogenic detector by Boyle and Rogers [12] in 1959. The carbon bolometer had a lot of advantages over the existing infrared detectors [13]. It was easy to build, inexpensive and of moderate heat capacity due to the low operating temperature. 

In case of ethanol, the sensitivity of the sensor to ethanol-contained air is about 1/S of that of methanol. Because the SA molecular sieve is designed for the separation of the molecular size of methanol, ethane and propane or smaller, the SA molecular sieve coated sensor gives much less sensitivity with ethanol contained air. Unlike other solid particle coated sensor, such as activated carbon sensor, the molecular sieve coated sensor has selectivity to the molecular size of detecting material. The outcome presented in Fig. 3 indicates that the sensor coated with SA molecular sieve satisfactorily discern methanol vapor from bigger molecules, but it does not separate from small molecules. When 4 A molecular sieve coated sensor is implemented to detect methanol, the same result of measuring ethanol with S A molecular sieve sensor is yielded as shown in Fig. 4. In other... 

Electrodes with covalently bound enzyme usually have a high functional stability. Bourdillon et al. (1982) observed 75% of the initial GOD activity after 30 days of intermittent use of a GOD-carbon sensor. When the enzyme was in continuous contact with glucose, autoinactivation caused an activity decay of 75% within 6 h. 

PHYSICOCHEMICAL PROPERTIES OE sp CARBON MATERIALS RELEVANT TO CARBON SENSORS... 

Evidently, this is another example of the extremely high selectivities that resnlt when the ionophores are very selective and the transfer of interfering ions into the sensing membrane is disfavored by the extremely low polarity and polarizability of fluorous phases (for other examples, see H+ sensors in Section 4.2 and the carbonate sensors in Section 4.5). Such high selectivities are also the key to low detection limits, and indeed Ag+.II has been used to demonstrate a detection limit for Ag" " of 4.1 ppt, which is the lowest detection limit obtained so far for an ionophore-based Ag+ ISE. 

L. D. Chen, D. Mandal, G. Pozzi, et al. Highly selective carbonate sensors with perfluorinated matrixes. Pittsburgh Conference of Analytical Chemistry, March 2011. Atlanta, GI, USA. 

Kalcher K, Svancara I, Metelka R, Vytfas K, Walcarius A (2006) Heterogeneous electrochemical carbon sensors. In Grimes CA, Dickey EC, Pishko MV (eds) Encyclopedia of sensors, vol IV. American Scientific Publisher, Stevenson Ranch, pp 283 29... 

The deterrnination of impurities in the hehum-group gases is also accompHshed by physical analytical methods and by conventional techniques for measuring the impurity in question (93), eg, galvanic sensors for oxygen, nondispersive infrared analysis for carbon dioxide, and electrolytic hygrometers for water. 

Ion-selective electrodes can also become sensors (qv) for gases such as carbon dioxide (qv), ammonia (qv), and hydrogen sulfide by isolating the gas in buffered solutions protected from the sample atmosphere by gas-permeable membranes. Typically, pH glass electrodes are used, but electrodes selective to carbonate or sulfide may be more selective. 

Mounting electrodes in a bioreactor is costly, and there is an additional contamination risk for sensitive cell cultures. Some other sensors of prac ticai importance are those for dissolved oxygen and for dissolved carbon dioxide. The analysis of gas exiting from a bioreactor with an infrared unit that detects carbon dioxide or a paramagnetic unit that detects oxygen (after carbon dioxide removal) has been replaced by mass spec trophotometry. Gas chromatographic procedures coupled with a mass spectrophotometer will detect 1 the volatile components. 

In this work, simple (single-use) biosensors with a layer double stranded (ds) calf thymus DNA attached to the surface of screen-printed carbon electrode assembly have been prepared. The sensor efficiency was significantly improved using nanostructured films like carbon nanotubes, hydroxyapatite and montmorillonite in the polyvinylalcohol matrix. 

Due to the very flexible synthetic approach, imprinted layers are highly suitable for sensor measurements in complex mixtures Sensor coatings consisting of a carbonic-acid-imprinted sol-gel material e.g. incorporate oxidative degradation products from engine oil leading to a chemical lubricant sensor. 

Carbonate ionophore I [ETH 6010] (heptyl 4-trifluoroacetylbenzoate) [129476-47-7] M 316.3, b 170°/0.02 Torr, d 0.909. Purified by flash chromatography (2g of reagent with 30g of Silica Gel 60) and eluted with EtOAc/hexane (1 19). The fractions that absorbed at 260nm were pooled, evapd and dried at room temp (10.3 Torr). The oily residue was distd in a bubbled-tube apparatus (170°/0.02 Torr). Its IR (CHCI3) had peaks at 1720, 1280, 940cm and its sol in tetrahydrofuran is 50mg/0.5mL. It is a lipophilic neutral ionophore selective for carbonate as well as being an optical humidity sensor. [Anal Chim Acta 233 41 1990.]... 

Afterburn Control. Afterburn is the term for carbon monoxide burning downstream of the regenerator this causes an increase in temperature upstream of the expander. Temperature sensors in the gas stream cause the brake to energize. This provides sufficient resisting torque to prevent acceleration until the afterburn is brought under control by water or steam injection. 

Maintenance "indicators" are available to help facility staff determine when routine maintenance is required. For example, air filters are often neglected (sometimes due to reasons such as difficult access) and fail to receive maintenance at proper intervals. Installation of an inexpensive manometer, an instrument used to monitor the pressure loss across a filter bank, can give an immediate indication of filter condition without having to open the unit to visually observe the actual filter. Computerized systems are available that can prompt staff to carry out maintenance activities at the proper intervals. Some of these programs can be connected to building equipment so that a signal is transmitted to staff if a piece of equipment malfunctions. Individual areas can be monitored for temperature, air movement, humidity, and carbon dioxide, and new sensors are constantly entering the market. 

Carbon monoxide and carbon dioxide can be measured using the FTIR techniques (Fourier transform infrared techniques see the later section on the Fourier transform infrared analyzer). Electrochemical cells have also been used to measure CO, and miniaturized optical sensors are available for CO 2 monitoring. 

Applicability of Semiconductor Gas Sensors Research into the applications of this type of sensor has mainly been concerned with measuring carbon monoxide concentration in flue gases. Tests show that sensors follow the concentration of carbon monoxide in the flue gas. Improvement in sensor performance has resulted with the introduction of a catalytic additive (palladium or... 

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