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Polarimeter/Polarimetry

Polarization is the most common method for the determination of sugar in sugar-containing commodities as well as many foodstuffs. Polarimetry is apphed in sugar analysis based on the fact that the optical rotation of pure sucrose solutions is a linear function of the sucrose concentration of the solution. Saccharimeters are polarimeters in which the scales have been modified to read directiy in percent sucrose based on the normal sugar solution reading 100%. [Pg.9]

In situ polarimetry could be performed using an eight axis SXR polarimeter [87] with multilayer optics mounted immediately behind the experimental chamber. Full determinations of the four Stokes parameters are time consuming. [Pg.301]

The basic experiment consisted of simply treating an l-UNCA with a base and monitoring the formation of the d-UNCA. The most straightforward analysis is accomplished by polarimetry. For example, Boc-Phe-NCA was dissolved in THF at a concentration of 0.33 M, and 1.5 equivalents of TEA were added. The resulting solution was placed in a polarimeter cell and the optical rotation was monitored over time (Figure 1). [Pg.664]

Substances that can rotate the orientation of plane-polarized light are said to have optical activity. Measurement of this change in polarization orientation is called polarimetry, and the measuring instrument is called a polarimeter. [Pg.702]

Polarimeter. An instrument for determining the concentration of optically active compounds in solution by determining the angle of rotation of plane-polarized light passing through the sample. See also Polarimetry,... [Pg.1295]

Chemistry Video Consortium, Practical Laboratory Chemistry, Educational Media Film and Video Ltd, Harrow, Essex, UK - Polarimetry, refractometry and radiochemistry (using a polarimeter, determining the refraetive indiees of liquids, measuring the rates of radioactive processes and measuring gas phase emission spectra). [Pg.248]

The separation of the enantiomorphous crystals of racemic sodium ammonium tartrate by Pasteur in 1848, and his observation that the two forms were optically active in solution, linked the concept of molecular chirality to optical activity [1]. When Emil Fischer began the first serious attempts at asymmetric synthesis in the latter 19th century, the polarimeter was the most reliable tool available to evaluate the results of an enantioselective reaction (by determination of optical purity), and it remained the primary tool for nearly 100 years. Only recently has analytical chemistry brought us to the point where we can say that polarimetry has been superceded as the primary method of analysis in asymmetric synthesis. [Pg.45]

If A < 16, then the optimal matrix inverse is the pseudo-inverse as well. However, in this case only fifteen or less of the Mueller matrix elements can be measured. The corresponding measurement apparatus is called an incom plete Mneller polarimeter. It is worth pointing ont the following advantages of Mneller polarimetry ... [Pg.251]

In practice, all 16 elements very often may not be independent. Some may be zero and some may be identical to others depending on symmetry and other physical properties of the studied object [7,8], A typical example is the deterministic class of objects which have less than seven independent elements. Hence, in measuring all 16 elements of the deterministic Mueller matrix, more than 50% are uni nformative measurements. This problem is relevant to imaging polarimetry, since time and storage requirements are important considerations. The number of independent elements of the Mueller matrix can be taken into account in developing a polarimeter. If one takes only three input polarizations, (4.9) can be stractured in the following way ... [Pg.253]

Polarimetry is a simple and accurate method for determining optically active compounds. A polarimeter is a low cost instrument readily available in many research laboratories. The detector can be integrated into an HPLC system if separation of substrates and products of reaction is required. Invertase ((3-D-fructofurano-side fructohydrolase EC 3.2.1.26), a commodity enzyme widely used in the food industry, can be conveniently assayed by polarimetry (Chen et al. 2000), since the specific optical rotation of the substrate (sucrose) differs from that of the products (fructose plus glucose). [Pg.14]

For a characterization within a series of compounds often polarimetry supersedes CD spectroscopy because the chosen concentration for its measurement is not restricted by a too high absorption. The broad acceptance of the polarimetric standardization of chiral compounds always has been a motivation for improvements of polarimeters. Especially for the daily routine work there is a requirement for instruments with high convenience (see section on Polarimetry and CD detectors in liquid chromatography). [Pg.641]

Polarimetry The determination of sucrose and reducing sugars in fruit and fruit products by polarimetry is an AOAC recommended method. The polarimeter measures the rotation of plane polarized light caused by a solution containing an optically active compound. Separate measurements for the quantification of sucrose and reducing sugars can be made with the Clerget-Hertzfeld double-polarization method. [Pg.1587]

Although preparative gas chromatography will yield enough sample to do spectra, it will not yield enough material to do the polarimetry. Therefore, if you are required to determine the optical rotation of the pure samples, whether or not you perform preparative gas chromatography, your instructor will provide a prefilled polarimeter tube for each sample. [Pg.133]

Polarimetry With the help of the instructor or assistant, obtain the observed optical rotation a of the pure (+)-carvone and (—)-carvone samples. These are provided in prefilled polarimeter tubes. The specific rotation [a]p is calculated from the relationship given in Technique 23, Section 23.2. The concentration c will equal the density of the substances analyzed at 20°C. The values, obtained from actual commercial samples, are 0.9608 g/mL for (+)-carvone and 0.9593 g/mL for (—)-carvone. The literature values for the specific rotations are as follows = +61.7° for (+)-carvone... [Pg.134]

The instructor may ask you to combine your remaining resolved naproxen with other students for determining the rotation of your (S)-naproxen by polarimetry. If so, your instructor will supply instructions. (S)-Naproxen has an observed specific rotation of +66°. The solvent, chloroform, will be used as the solvent, unless you are told otherwise. Calculate the % optical purity (% enantiomeric excess) for your sample and compare the results with the chiral HPLC results. Remember that the sample may only contain about 82% of the (S) enantiomers (Technique 23, Section 23.5) so you will not obtain a value of +66° from the polarimeter. [Pg.547]


See other pages where Polarimeter/Polarimetry is mentioned: [Pg.249]    [Pg.1036]    [Pg.157]    [Pg.223]    [Pg.19]    [Pg.1321]    [Pg.247]    [Pg.110]    [Pg.247]    [Pg.262]    [Pg.283]    [Pg.247]    [Pg.187]    [Pg.388]    [Pg.24]    [Pg.1171]    [Pg.388]    [Pg.388]    [Pg.198]    [Pg.215]    [Pg.4]    [Pg.388]    [Pg.326]    [Pg.387]    [Pg.481]    [Pg.309]    [Pg.181]    [Pg.4730]    [Pg.67]    [Pg.328]   
See also in sourсe #XX -- [ Pg.851 , Pg.851 ]




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