Enhanced detection

Most sample components analyzed with electrophoretic techniques are invisible to the naked eye. Thus methods have been developed to visualize and quantify separated compounds. These techniques most commonly involve chemically fixing and then staining the compounds in the gel. Other detection techniques can sometimes yield more information, such as detection using antibodies to specific compounds, which gives positive identification of a sample component either by immunoelectrophoretic or blotting techniques, or enhanced detection by combining two different electrophoresis methods in two-dimensional electrophoretic techniques. 

Thermostable pectinesterases (TSPE), operationally defined as activity that survives 5 min at 70°C, contribute most to cloud loss in juices at low temperatures and juice pH (26). The percentage of total activity that is thermostable is highly variable and differs in kinetic properties, (22, 26), ease of solubilization (28, 29), stability to low pH (25) and stability to freeze-thaw cycles (23). Some of the variability in reported total PE and TSPE may be related to limitations of current methods to quantify activity. Any processing treatment or assay condition that increases cell wall breakdown or release PE from a pectin complex would enhance detection of total and TS-PE activity. Commercially, PE is inactivated by pasteurization in a plate heat exchanger or during concentration in the TASTE evaporator. 

In TLC the detection process is static (sepaurations achieved in space rather than time) and free from time constraints, or from interference by the mobile phase, which is removed between the development and detection process. Freedom from time constraints permits the utilization of any variety of techniques to enhance detection sensitivity, which if the methods are nondestructive, nay be applied sequentially. Thus, the detection process in TLC is nore flexible and variable than for HPLC. For optical detection the minimum detectable quantities are similar for both technlqpies with, perhaps, a slight advantage for HPLC. Direct comparisons are difficult because of the differences in detection variables and how these are optimized. Detection in TLC, however, is generally limited to optical detection without the equivalent of refractive... 

Mikhitarian K, Reott S, Hoover L, et al. Enhanced detection of RNA from paraffin-embedded tissue using a panel of truncated gene-specific primers for reverse transcription. BioTechniques 2004 36 474 178. 

Figure 7.21 Dendrimers that are fluorescently labeled as well as biotinylated create enhanced detection reagents for use in (strept)avidin-biotin-based assays. Large complexes containing multiple fluorescent dendrimers can bind to antigens and form a highly sensitive detection system that exceeds the detection capability of fluorescently labeled antibodies.

Microcavity-Enhanced Detection of Atmospheric Trace Gases... 

Two methods of further enhancing detection sensitivity rely on the use of multiple resonators or multiple fiber modes. The first will just be mentioned briefly, because although it is absorption based it uses a frequency shift. When two microresonators have resonances that are coincident in frequency, and the second resonator is brought near to the first resonator, which is in contact with the coupling fiber, the... 

The enhanced evanescent field, as confirmed by the coupling enhancement results noted above, has been shown to significantly enhance detection sensitivity in preliminary experiments using dye in water solution at 800 nm. In addition, a... 

In recent years, rapid advancements in photonic technologies have significantly enhanced the photonic bio/chemical sensor performance, especially in the areas of (1) interaction between the light and analyte, (2) device miniaturization and multiplexing, and (3) fluidic design and integration. This has led to drastic improvements in sensor sensitivity, enhanced detection limit, advanced fluidic handling capability, lower sample consumption, faster detection time, and lower overall detection cost per measurement. 

The polymers used for fluorescence detection discussed thus far have all used either a synthetically linked polymer as the signal transducer for enhanced detection or some type of hybridization of the polymer with a receptor for ligand-receptor binding signaling. One of the most notable aspects of CPs is their ability to act as direct reporters for the detection of small molecules, or for conformational changes and protein aggregates. 

FIAs can be based on steady-state intensity measurements without probe amplification, owing to the sensitivity of detection that is possible with fluorescence instrumentation, which exceeds that of spectrophotometers by two or three orders of magnitude. A sensitive fluorometer has been described for an estradiol assay(36) in which the limit of estradiol detection is 3 x KT11 M. Estradiol antibody labeled with rhodamine B is reacted with estradiol samples. Unreacted labeled antibody is removed with Sepharose-estradiol-casein beads, and the remaining fluorescence is directly proportional to the analyte concentration. The detection limit of rhodamine B on the same fluorometer is 5 x 1(T12 M. This instrument uses a 0.75 mW green helium-neon (HeNe) laser to irradiate the sample from above, at the air-liquid interface, to increase the light path and to decrease surface reflections. The sample compartment has a top-mounted photon trap, and a mirror mounted on the side of the sample compartment opposite the PMT to enhance detection. 

Steffa R.J. and R.M. Atlas. 1988. DNA amplification to enhance detection of genetically engineered bacteria in environmental samples. Appl. Environ. Microbiol. 54 2185-2191. 

There was no mutagenic enhancement detected in the sera of animals implanted with tantalum pellets. ... 

Dilsizian V, Rocco TP, Freedman NM, Leon MB, Bonow RO. Enhanced detection of ischemic but viable myocardium by the reinjection of thalhum after stress-redistribution imaging. N Engl J Med 1990 323 141-146... 

Schlegel TT, Kulecz WB, DePahna JL, et al. Real-time 12-lead high-frequency QRS electrocardiography for enhanced detection of myocardial ischemia and coronary artery disease. Mayo Clin Proc. Mar 2004 79(3) 339-350. 

The need for enhanced detection sensitivity and automation has steadily increased for the separation and analysis of peptides from natural sources or proteolytic digestion of low abundance proteins this is also partly a consequence of the greater usage of combinatorial solid-phase synthetic approaches. Narrow bore (1-2 mm i.d.), microbore (0.5-1.0 mm i.d.), and capillary (100-500 pm i.d.) columns have provided attractive solutions to these problems. 1221 An important attribute of very small particle diameter micropellicular, porous, or nonporous RPC sorbents is that they are ideally suited to such microbore or capillary... 

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