Indicators reagents

In each of the following pairs of compounds choose which one will react faster with the indicated reagent and wnte a chemical equation for the faster reaction... 

Choose which member in each of the following pairs reacts faster or has the more favor able equihbnum constant for reaction with the indicated reagent Explain your reasoning... 

Fluorescence Immunoassay. Basic FIA follows the same formats and approaches as EIA. The difference Hes in the indicator a fluotophote is used instead of an enzyme. This allows direct quantification of the indicatot—antibody—antigen complex, or free indicator-reagent, without the need for a substrate. 

B. Self-indicating reagents. This is well illustrated by potassium permanganate, one drop of which will impart a visible pink coloration to several hundred millilitres of solution, even in the presence of slightly coloured ions, such as iron(III). The colours of cerium(IV) sulphate and of iodine solutions have also been employed in the detection of end points, but the colour change is not so marked as for potassium permanganate here, however, sensitive internal... 

Indicate reagents and approximate reaction conditions that could be used to effect the following transformations. More than one step may be required. 

Indicate reagents or short reaction sequences that could accomplish the synthesis of the target on the left from the starting material on the right. 

Scheme 9.8 The synthesis of methyl pentamannoside 2. The numerals indicate reagents used in the synthetic sequence (1) trimethylsilyl triflate, methylene chloride, 4 A molecular sieves (2) DBU, methanol. The final deprotection conditions shown in Scheme 9.7 were employed.

E Atherton, JL Holder, MMeldal, RC Sheppard, RM Valerio. 3,4-Dihydro-4-oxo-l,2,3-benzotriazin-3-yl esters of fluorenylmethoxycarbonyl amino acids as self-indicating reagents for solid phase peptide synthesis. J Chem Soc Perkin Trans 1 2887, 1988. 

Exercise 16-46 Propose a possible synthesis of each of the following compounds from the indicated reagents and conditions where specified. Assume that any additional needed reagents are available. Reactions from other parts of Section 16-9 may be used. 

The principle approach to immunoassay is illustrated in Figure 1, which shows a basic sandwich immunoassay. In this type of assay, an antibody to the analyte to be measured is immobilized onto a solid surface, such as a bead or a plastic (microtiter) plate. The test sample suspected of containing the analyte is mixed with the antibody beads or placed in the plastic plate, resulting in the formation of the antibody—analyte complex. A second antibody which carries an indicator reagent is then added to the mixture. This indicator may be a radioisotope, for RIA an enzyme, for EIA or a fluorophore, for fluorescence immunoassay (FIA). The antibody-indicator binds to the first antibody—analyte complex, free second antibody-indicator is washed away, and the two-antibody—analyte complex is quantified using a method compatible with the indicator reagent, such as quantifying radioactivity or enzyme-mediated color formation (see Automated instrumentation, clinical chemistry). 

To 100-mL sample, add 1 mL acidified indicator reagent. The solution should become greenish-blue. If the color is pure blue, the pH is above 3.8, while a light green color indicates a pH less than 2. The pH adjustment is very crucial in this analysis. Titrate the sample with 0.0141 ArHg(N03)2. Prior to the end point, the solution turns blue at the end point, the color becomes purple. Perform a blank titration using distilled water. 

E. Ross, J. Kothe, R. Naumann, W. Fischer, W.-D. Mayer, G. Wieland, E. J. Newman, C. M. Wilson, Indicator Reagents , Ullmann s Encyclopedia of Industrial Chemistry, 6th ed., Electronic Release, Wiley-VCH, Weinheim, 2002. 

Fiber-optic sensors based on controlled-release polymers provide sustained release of indicating reagents over long periods. This technique allows irreversible chemistries to be used in the design of sensors for continuous measurements. The sensor reported in this paper is based on a fluorescence energy transfer immunoassay. The sensor was cycled through different concentrations of antigen continuously for 30 hours. 

Roman numerals indicate reagents required for experiments in the text of that chapter. Reagents required for experiments in questions at the end of a preparation are indicated by the letter Q and number of the preparation. Reagents used in a preparation are designated by the letter P and number of the preparation. 

Arrange the compounds in each set in order of reactivity toward the indicated reagent. Give the structure and name of the product expected from the compound you select as the most reactive in each set. 

Indicator reactions that are chemical in nature may be introduced either into the mobile phase or at the end of the column by the method of postcolumn reagent addition. Postcolumn addition of reagents dilutes the column eluent, so that, when possible, the addition of indicator reagents to the mobile phase is preferable. 

Use Dyes, especially sulfur colors picric acid, pi-cramic acid, preservation of lumber, manufacture of the photographic developer diaminophenol hydrochloride, explosives manufacture indicator, reagent for potassium and ammonium ions. 

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