Glucose polarimetry

Polarimetry is extremely useful for monitoring reactions of optically active natural products such as carbohydrates which do not have a useful UV chromophore, and samples for study do not need to be enantiomerically pure. Nevertheless, compared with spectrophotometry, the technique has been applied to relatively few reactions. It was, however, the first technique used for monitoring a chemical reaction by measuring a physical property when Wilhemy investigated the mutarotation of sucrose in acidic solution and established the proportionality between the rate of reaction and the amount of remaining reactant [50]. The study of a similar process, the mutarotation of glucose, served to establish the well-known Bronsted relationship, a fundamental catalysis law in mechanistic organic chemistry. 

Wan QJ, Cote GL, Dixon IB. Dual-wavelength polarimetry for monitoring glucose in the presence of varying birefringence. Journal of Biomedical Optics 2005, 10, 024029. 

Various refinements of starch content analysis have been reported. The methods are based on starch hydrolysis, followed by polarimetry,305 high-pressure liquid chromatography306 or reaction with glucose oxidase/peroxidase.307,308 An iodine reaction can be used to determine the botanical origin of starch.309 The molecular weight distribution is determined by size-exclusion chromatography.310,311... 

The isomerization reaction may be monitored by polarimetry. As the conversion of D-glucose into D-fructose causes a decrease in the specific rotation namely, [a]D25 - 140° (c 0.1, water), polarimetry provides a very sensitive, control technique. 

These two hexoses are in me D series. The absolute configuration of mis asymmetrical carbon does not, however, predict its optical activity assessed by polarimetry. Thus, D-fructose is strongly anticlockwise in water while D-glucose is clockwise. The optical activity of a chiral molecule is determined by experimental measurement. The value depends on bom me molecule s structure and me experimental conditions (temperature, solvent, pH, etc.). 

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). 

Emil Fischer s determination of the structure of glucose was carried out as the nineteenth century ended and the twentieth began. The structure of no other sugar was known at that time, and the spectroscopic techniques that now aid organic analysis were not yet available. All Fischer had was information from chemical transformations, polarimetry, and his own intellect. 

An easy and sensitive method to measure protein denaturation is to use enzymes as the proteinaceous substrate for the test product. An irritant surfactant incubated with the enzyme will lead to a loss of the enzymatic activity of the protein proportional to the level of irritancy of the surface agent. The better known enzyme inhibition test is using sac-charase as the enzyme, measuring by polarimetry the amount of glucose formed from sucrose in the presence and the absence of the detergent [13]. 

Noninvasive techniques include infrared, Raman spectroscopy, polarimetry, l ht scattering, photoacoustic spectroscopy, polarization technique, and impedance. In infiared spectroscopy, absorption or emission data in the region of spectrum are compared to known data for glucose. In Raman spectroscopy, laser light is used to... 

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