Electrophoresis INDEX

The sensors in this section can also be utilized to detect chemicals in liquid through the bulk solution refractive index change induced by the presence of target chemicals. Since no recognition molecules are used, this type of chemical sensing may usually have low specificity. However, these sensors may perform excellently in conjunction with other technologies such as capillary electrophoresis, mass spectrometer, and liquid chromatography in chemical detection. 

Krattiger B, Bruin GJM, Bruno AE. Hologram-based refractive-index detector for capillary electrophoresis—Separation of metal-ions. Analytical Chemistry 66, 1-8, 1994. 

Deng YZ, Li BC. On-column refractive-index detection based on retroreflected beam interference for capillary electrophoresis. App/ierf Optics 37, 998-1005, 1998. 

An increased IgM index is seen in cerebral lupus erythematosus and in 30-60% of multiple sclerosis patients with a short disease duration (A20, A24, L1). An increase in the IgM index is usually associated with oligoclonal IgM bands on electrophoresis. This indicates an oligoclonal aspect of intrathecally produced IgM. Cerebral IgM production is related to the activity of multiple sclerosis, and the early detection of oligoclonal IgM in patients with acute isolated lesions of the brainstem and spinal cord has more predictive value for the development of multiple sclerosis than does detection of oligoclonal IgG bands (LI). 

The schlieren system of optics is an analytical method that is particularly well suited to following the location of a chemical boundary with time. It is routinely employed in ultracentrifuges and also in electrophoresis experiments, as we see in Chapter 12. Schlieren optics produces an effect that depends on the way the refractive index varies with position, that is, the refractive index gradient rather than on the refractive index itself. Therefore, the schlieren effect is the same at all locations along the axis of sedimentation, except at any place where the refractive index is changing. In such a region, it will produce an optical effect that is proportional to the refractive index gradient. The boundary between two layers is thus per-... 

Spectrophotometry, 42 Absorbance, 42 Infrared, 44 Luminescence, 45 Raman, 48 Fiber Optics, 50 Refractive Index, 52 Piezoelectric Mass Sensors, 53 New Chemistry, 54 Immunochemistry, 54 Polymers and New Materials, 56 Recognition Chemistry, 57 Chromatography and Electrophoresis, 61 Flow Injection Analysis and Continuous Flow Analysis, 63 Robotics, 65 Chemometrics, 68 Communications, 70... 

Significant advances have occurred during the past decade to miniaturize the size of the measurement system in order to make online analysis economically feasible and to reduce the time delays that often are present in analyzers. Recently, chemical sensors have been placed on microchips, even those requiring multiple physical, chemical, and biochemical steps (such as electrophoresis) in the analysis. This device has been called lab-on-a-chip. The measurements of chemical composition can be direct or indirect, the latter case referring to applications where some property of the process stream is measured (such as refractive index) and then related to composition of a particular component. 

Index Entries Recombinant green fluorescent protein GFPuv hydro-phobic interaction chromatography sodium dodecylsulfate polyacrylamide gel electrophoresis three-phase partitioning extraction. 

Fortini AS, Sanders EL, Weinshenker BG, Katzmann JA (2003) Cerebrospinal fluid oligoclonal bands in the diagnosis of multiple sclerosis. Isoelectric focusing with IgG immunoblotting compared with high-resolution agarose gel electrophoresis and cerebrospinal fluid IgG index. Am J Clin Pathol 120 672-675. 

Homoserine elutes from the 60 cm column of a Beckman 120C analyzer just prior to glutamic acid and has a color value 95 % that of leucine (Hofmann 1964). Better separation of homoserine and glutamic acid can be achieved by lowering the pH of the eluting buffer to 3.20 (Ambler 1965) or to 2.80 (Schroeder et al. 1967). Homoserine has a mobility of 1.37 compared to 1.00 for aspartic acid in pH 1.9 electrophoresis. Subject index p. 201... 

The Ma value has been suggested f >- as a convenient index of the mobility of a carbohydrate in zone electrophoresis. The Mg value, which bears a formal resemblance to the Rg value employed in chromatography, is given by... 

With CE, separated analytes are detected and measured as they migrate past an optical detector without prior staining. Optical detection is based on classical methods, such as photometric absorbance, refractive index, and fluorescence (see Chapter 3). These techniques miniaturize and simplify the process of measurement by eliminating several of the steps required in conventional gel electrophoresis. Because the amount of protein measured and the measurement path are both very small, however, special conditions are often used to improve sensitivity. 

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