Carbon dioxide sensors detection

Electrocatalytic groups such as porphyrins and phthalocyanines that act as supramolecular hosts for different metals and mimic the active sites of various proteins are commonly used in amperometric sensors [66,67]. A biomimetic sensor based on an artificial enzyme or synzyme has been demonstrated [68]. The artificial enzyme used in this study was a synthetic polymer (quaternised polyethyleneimine containing 10% primary amines) which decarboxylated oxaloacetate. The product carbon dioxide was detected potentiometrically via a gas membrane electrode. 

Desai, R.R., Lakshminarayana, D., Ratel, R.B. and Ranchal, C.J. (2005), Indinm ses-quitelluride (In2Te3) thin film gas sensor for detection of carbon dioxide . Sensors and Actuators B Chemical, 107,2,523-7. 

Ishihara T, Kometani K, Mizuhara Y, Takita Y (1991a) Mixed oxide capacitor of CuO-BaSnOj as a sensor for CO detection over a wide range of concentration. Chem Lett 20(10) 1711-1714 Ishihara T, Kometani K, Hashida M, Takita Y (1991b) Application of mixed oxide capacitor to the selective carbon dioxide sensor. I. Measurement of carbon dioxide sensing characteristics. J Electrochem Soc 138 173-176 Ishihara T, Kometani K, Mizuhara Y, Takita Y (1992) Application of a mixed oxide capacitor to the selective carbon dioxide sensor. II. COj sensing characteristics of a CuO-based oxide capacitor. J Electrochem Soc 139 2881-2885... 

Ridgway ST (2004) Optical coatings for CHARA reflective optics. CHARA Technical Report No. 911, October 2004 Riris H, Carlisle CB, Carr LW, Cooper DE, MartineUi RU, Menna RJ (1994) Design of an open path near-infiured diode laser sensor application to oxygen, water, and carbon dioxide vapor detection. Appl Opt 33 7059-7066 Rouessac F, Rouessac A (2007) Chemical analysis modem instrumentation methods and techniques. Wiley, Chichester... 

Dansby-Sparks RN, Jin J, Mechery SJ et al (2010) Fluorescent-dye-doped sol—gel sensor for highly sensitive carbon dioxide gas detection below atmospheric concentrations. Anal Chem 82 593-600... 

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infrared unit that detects carbon dioxide or a paramagnetic unit that detects oxygen (after carbon dioxide removal) has been replaced by mass spec trophotometry.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. 

Mabbit, Allen, and Andrew Parker. Methane, and Carbon Dioxide Detection Using LED Sources. Sensor Rev. 16 (1996), pp. 38-41. 

Because of the role these algae play in the oceans biological productivity and their impacts on climate due to the removal of carbon dioxide, satellite sensors have been employed to measure the chlorophyll a contents in oceans, lakes, and seas to indicate the distribution and abundance of biomass production in these water bodies. Detection is set at the specific reflectance and absorption wavelengths of the light from the upper layer of the ocean where photosynthesis occurs. 

Many different types of sensory receptors are located throughout the body. These receptors monitor the status of the internal environment or that of the surroundings. Sensory receptors are sensitive to specific types of stimuli and measure the value of a physiological variable. For example, arterial baroreceptors measure blood pressure and chemoreceptors measure the oxygen and carbon dioxide content of the blood. The information detected by these sensors then travels by way of afferent neuronal pathways to the central nervous system (CNS). The CNS is the integrative portion of the nervous system and consists of the (1) brain and the (2) spinal cord. 

Clinical chemistry, particularly the determination of the biologically relevant electrolytes in physiological fluids, remains the key area of ISEs application [15], as billions of routine measurements with ISEs are performed each year all over the world [16], The concentration ranges for the most important physiological ions detectable in blood fluids with polymeric ISEs are shown in Table 4.1. Sensors for pH and for ionized calcium, potassium and sodium are approved by the International Federation of Clinical Chemistry (IFCC) and implemented into commercially available clinical analyzers [17], Moreover, magnesium, lithium, and chloride ions are also widely detected by corresponding ISEs in blood liquids, urine, hemodialysis solutions, and elsewhere. Sensors for the determination of physiologically relevant polyions (heparin and protamine), dissolved carbon dioxide, phosphates, and other blood analytes, intensively studied over the years, are on their way to replace less reliable and/or awkward analytical procedures for blood analysis (see below). 

Reflectance measurements provided an excellent means for building an ammonium ion sensor involving immobilization of a colorimetric acid-base indicator in the flow-cell depicted schematically in Fig. 3.38.C. The cell was furnished with a microporous PTFE membrane supported on the inner surface of the light window. The detection limit achieved was found to depend on the constant of the immobilized acid-base indicator used it was lO M for /7-Xylenol Blue (pAT, = 2.0). The response time was related to the ammonium ion concentration and ranged from 1 to 60 min. The sensor remained stable for over 6 months and was used to determine the analyte in real samples consisting of purified waste water, which was taken from a tank where the water was collected for release into the mimicipal waste water treatment plant. Since no significant interference fi-om acid compounds such as carbon dioxide or acetic acid was encountered, the sensor proved to be applicable to real samples after pH adjustment. The ammonium concentrations provided by the sensor were consistent with those obtained by ion chromatography, a spectrophotometric assay and an ammonia-selective electrode [269]. 

The analytes typically determined by using this type of sensor are those usually addressed by gas-diffiision systems, viz. ammonia (or ammonium ion), carbon dioxide (or carbonates) and oxygen. The detection system used is most frequently photometric, fluorimetric or potentiometric, and can be integrated with or connected to the sensing microzone. The description below is based on the two choices shown in Fig. 5.4. 

One could immobilize the urease layer on top of a Severinghaus electrode for CO2 or NH3 (Section 6.3.2) and use the device as an enzymatic-potentiometric gas sensor. The primary disadvantage of such an arrangement would be its slow response time. A more direct way is through the detection of the ionic species resulting from the hydrolysis of ammonia and carbon dioxide. 

Ruthenium complexes with mixed bipyridyl ligands, immobilized inside a Nation film, may also be used as pH-sensitive sensor layers [90]. A completely different approach for a ratiometric imaging of pH sensor foils was developed for diagenetic studies of marine sediments, using the dual fluorescence excitation ratio of the pH-sensitive fluorophore 8-hydroxypyrene-l,3,6-trisulfonic acid (HPTS) [91]. Commonly used dual fluorophors with different absorption and emission maxima in the protonated and basic form for ratiometric measurements are the naphthofluorescein and seminaphthofluorescein derivates (SNARF and SNAFL) [92], It should be noted that ammonia or carbon dioxide can also be detected by some of these pH-sensitive materials [55,93]. 

In a few cases, small optical infrared absorption monitors have been integrated into electronic nose sensors [11], mostly for detection of the carbon dioxide evolution from cells. The 3000-4000 nm filters are normally used. 

All of the aforementioned biosensors are designed for a standard stirred-tank bioreactor they will not work with smaller-scale vessels such as shake flasks. Small noninvasive sensors have been developed to measure D.O. and pC02 inside shake and T-flasks40,41 A D.O. or pC02 detecting patch is placed in the flask, and this patch contains an oxygen or carbon dioxide luminescent dye. The color shifts of these dyes are detected using an external fluorometer. 

There are various potential applications of photophysical phenomena in analytical chemistry. The relatively short lifetimes of most excited states, however, is a serious drawback to the construction of practical devices but studies which focus on finding ways to extend triplet lifetimes have now been described by Harriman et al. Kneas et al. have examined new types of luminescent sensor on polymer supports, and both Neurauter et al. and Marazuela et al. have designed sensors based on the ruthenium(II) polypyridine complex for the detection of carbon dioxide. A system, based on the formation of twisted intramolecular charge transfer states, has been devised for measuring the molecular weight of polymeric matrices (Al-Hassan et a/.), and the chemical reactivity at the interface of self-assembled monolayers has been assessed using fluorescence spectroscopy (Fox et al). 

An H" ISE may be designed to detect gaseous carbon dioxide when it is isolated from the test solution by a second membrane. Operation of the sensor is based on the reaction... 

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