Fluorescence chemiluminescence

As it was indicated above, the main optical interrogation methods include absorbance, reflectance, fluorescence, chemiluminescence (CL), or electrogenerated chemiluminescence (ECL)9,41"42. 

Urdea, M.S., Warner, B.D., Running, J.A., Stempien, M., Clyne, J., and Horn, T. (1988) A comparison of non-radioactive hybridization assay methods using fluorescent, chemiluminescent and enzyme-labeled synthetic oligodeoxyribonucleotide probes. Nucleic Acids Res. 16, 4937-4956. 

DPA) in dimethylphthalate at about 70°, yields a relatively strong blue Umax =435 nm) chemiluminescence the quantum yield is about 7% that of luminol 64>. The emission spectrum matches that of DPA fluorescence so that the available excitation energy is more than 70 kcal/mole. Energy transfer was observed on other fluorescers, e.g. rubrene and fluorescein. The mechansim of the phthaloyl peroxide/fluorescer chemiluminescence reaction very probably involves radicals. Luminol also chemiluminesces when heated with phthaloyl peroxide but only in the presence of base, which suggests another mechanism. The products of phthaloyl peroxide thermolysis are carbon dioxide, benzoic acid, phthalic anhydride, o-phenyl benzoic acid and some other compounds 65>66>. It is not yet known which of them is the key intermediate which transfers its excitation energy to the fluorescer. 

The non-radioactive labeling utilizes fluorescence, chemiluminescence, or biotin/avidin interactions. Capillary electrophoresis with laser-induced fluorescence was first employed in PAL by Miller et al. [51]. Gilbert and Rando recently reported several biotin-containing heterobifunctional reagents and used them successfully [18] (Fig. 5). 

From a general point of view, a chemical sensor is a device capable of continuously monitoring the concentration of an analyte. The two main classes are electrochemical sensors and optical chemical sensors. The latter are based on the measurement of changes in an optical quantity refractive index, light scattering, reflectance, absorbance, fluorescence, chemiluminescence, etc. For remote sensing, an optical fiber is used, and the optical sensor is then called an optode because of... 

Finally, we must point out that nowadays the widely extended RILAs are basically used for MIP characterization purposes. In a general way, the use of RILAs has been reduced drastically in the last few years. The literature shows that they have been replaced by other tracers with fluorescence, chemiluminescence or absorbance detection often combined with labeled enzymes. Simplicity in their use, easy access to these techniques, and the lack of radioactive compounds are the main reasons for such substitution. 

The transducers most commonly employed in biosensors are (a) Electrochemical amperometric, potentiometric and impedimetric (b) Optical vibrational (IR, Raman), luminescence (fluorescence, chemiluminescence) (c) Integrated optics (surface plasmon resonance (SPR), interferometery) and (d) Mechanical surface acoustic wave (SAW) and quartz crystal microbalance (QCM) [4,12]. 

Method of detection Fluorescence Chemiluminescence Fluorescence Change in pH... 

Other techniques to be investigated for analyzing effects of oxidation on fatty derivatives include monitoring PV, conjugated dienes, anisidine value, and carbonyls. Spectroscopic methods include electron spin resonance, infrared, fluorescence, chemiluminescence, and NMR (Shahidi and Wanasundara, 1998). 

Note A spectrofluorimeter is quite different from a luminometer (which measures chemiluminescence), and it is important not to confuse the two. Unlike fluorescence, chemiluminescence relies on a chemical reaction between, for example, firefly luciferase and luciferin and molecules in the sample. For measures of chemiluminescence, molecules promoted to an excited state as a result of the reaction return to the ground state with emission of light, which can be measured. 

Figure 1.1 A schematic diagram of the unified plasmon/fluorophore description. Fluorophores induce surface plasmons in metals and energy is effectively transferred in a non-radiative fashion. This interaction of excited states with surface plasmons leads to a wealth of new fluorescence, chemiluminescence and phosphorescence phenomena and technologies we describe as a Unified Description.

While compendial standards are available for some monographed article impurities, it may be difficult at times to obtain pure standards of impurities. Manufacturers of pharmaceuticals function as a potential source for obtaining reference standards of impurities, which may be synthesis precursors, process intermediates, or degradation products. The characterization and evaluation of these impurities reference standards should be constant with their intended use. In many cases, analytical procedures are developed and validated, where the response of an impurity is compared to that of the new drug substance itself. Response factor evaluation of impurities at the chosen detection wavelength is necessary to determine if a correction factor is needed (when the responses differ). Potentiometric detection, fluorescence/ chemiluminescence detection, and refractive index detection are some examples of detection modes available for compounds that may not be suitable for UV detection. 

Schulman JM, Schuhnan SG. Phosphorescence, fluorescence, chemiluminescence in clinical chemistry. In Meyers RA, ed. Encyclopedia of analytical chemistry Applications, theory, and instrumentation. New York John Wiley Sons, 2000 1570-82. 

Methods in which some property related to substrate concentration (such as absorbance, fluorescence, chemiluminescence, etc.) is measured at two fixed times during the course of the reaction are known as two-point kinetic methods. They are theoreticahy the most accurate for the enzymatic determination of substrates. However, these methods are technically more demanding than equifibrium methods and all the factors that affect reaction rate, such as pH, temperature, and amount of enzyme, must be kept constant from one assay to the next, as must the timing of the two measurements. These conditions can readily be achieved in automatic analyzers. A reference solution of the analyte (substrate) must be used for calibration. To ensure first-order reaction conditions, the substrate concentration must be low compared to the K, (i.e., in the order of less than 0.2 X K, . Enzymes with high K , values are therefore preferred for kinetic analysis to give a wider usable range of substrate concentration. 

A) Fluorescence/Chemiluminescence Techniques. Lipid hydroperoxides can be reacted with chemiluminescent indicators such as luminol or diphenyl-l-pyrenylphosphine post-HPLC , which allows separation and identification of phospholipid and cholesterol ester peroxides . This technique is applicable to both conjugated and non-conjugated lipids, however it tends to involve a relatively long delay between injection and final fluorescent analysis, and it probably provides inaccurate assessments of total levels of peroxide . ... 

Flavor compounds, detection of 938 Flavyhum salts 1029 Floating peroxyl radical theory 889 Fluorescence/chemiluminescence techniques, in measurement of antioxidant efficiency 853, 854... 

Depending on the excitation method used, luminescence techniques are divided into photoluminescence excited by photons, cathodoluminescence generated under the action of cathode rays, X-ray luminescence excited by X-rays, candoluminescence generated under the action of heat, and sonoluminescence excited by ultrasound. Emission generated under the action of a stream of ions from alkali metals in vaccum is called ionoluminescence radiation which atoms emit on optical excitation in plasma is known as atomic fluorescence chemiluminescence is the emission of radiation generated by the energy of chemical reactions, it does not require an external excitation source. The excitation source needed in each particular case is chosen on the basis of this classification. 

Abstract Optical detection continues to dominate detection methods in microfluidics due to its noninvasive nature, easy coupling, rapid response, and high sensitivity. In this review, we summarize two aspects of recent developments in optical detection methods on microfluidic chips. The first aspect is free-space (off-chip) detection on the microchip, in which the conventional absorption, fluorescence, chemiluminescence, surface plasmon resonance, and surface enhanced Raman spectroscopies are involved. The second aspect is the optofluidic (inside-chip) detection. Various miniaturized optical components integrated on the microfluidic chip, such as waveguide, microlens, laser, and detectors are outlined. 

Pyrolysis kinetics, including Toluene carrier tech Very low pressure pyrolysis (VLPP) Concentration of atoms, free radicals and molecules vs. time at different temperatures, using various detecting techniques, such as GC, HPLC, MS, FT-IR, UV/VIS, EPR, NMR, resonance fluorescence, chemiluminescence, and so on Species in gas and solution phase 1950SZW (1) 1973GOL/SPO (2) 1979ROS/KIN (3) 1982MCM/GOL... 

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