Optical Rotation—A Reliable Parameter for Authentication of Honey?

Chiral molecules are characterized by a specific rotation angle, the angle through which plane-polarized light is rotated on passing through an enantiomerically enriched solution. Recent developments in methodology allow computation of both the sign and the magnitude of these rotation angles. However, a general strategy for assigning the individual contributions that atoms and functional groups make to the optical rotation angle and, more generally, to the molecular chirality has remained elusive. Here, a method to determine the atomic contributions to the optical rotation angle is reported. This approach links chemical structure with optical rotation angle and provides a quantitative measure of molecular asymmetry propagation from a center, axis, or plane of chirality.

Honeydew honey, due to its higher antibacterial and antioxidant activity in comparison to blossom honeys, is in high demand and of interest to consumers. Although a differentiation of blossom honeys from honeydew honeys by way of electrical conductivity is given in many cases, criteria for a differentiation of individual honeydew honeys, such as spruce, fir, and pine, however did not exist. For this reason, 93 authentic honeydew honeys and 63 non-honeydew honeys [35 blossom and 28 nectar-honeydew (mixed)] from 13 different botanical origins were collected within the framework of the current study, and their electrical conductivity and phenolic and sugar profiles were investigated. Results showed that the higher electrical conductivity (≥0.80 mS/cm), the higher protocatechuic acid content (≥3.5 mg/kg), and the higher percentage of the oligosaccharide content (≥120 mg/g) were suitable parameters for the differentiation of authentic coniferous honeydew honeys from non-honeydew honeys; a differentiation. A differentiation of the spruce, fir, and pine honeydew honeys however could not be reached. Through the analysis of 32 carbohydrates (2 mono-, 7 di-, 10 tri-, and 13 higher oligosaccharides) in only one run by high-performance liquid chromatography equipped with an evaporative light scattering detector, marker substances can now be utilized for the classification of individual honeydew honeys. Sugar marker compounds such as α,α-trehalose, melezitose, theanderose, nystose, or maltotetraose in honeydew honeys in combination with chemometrics highlighted the good capability of sugar profiles to discriminate the honeydew honeys both from the non-honeydew honeys and from each other. All in all, a 96.75% correct classification of all studied 156 honey samples was achieved by sugar marker compounds.

We fabricated a device equipped with a microchannel on a complementary metal oxide semiconductor (CMOS) sensor to observe the optical polarization rotation angle during in situ monitoring. The sensor is based on the integrated wire-grid polarization detection method. The microchannel is fabricated on a Si layer by deep reactive ion etching (DRIE). Using this device, we measured the optical rotation of chiral molecules in a microfluid. This showed that the device is applicable to in situ chiral measurement. Optical rotation angles of the linearly polarized light corresponded to different concentrations of sucrose solution. Sensor output reflecting the temporal concentration change of chiral molecules was also observed. These results clearly demonstrate that the CMOS sensor has the capability of measuring chiral molecules in situ.

Rotatory dispersion in optical activity and a rotary Fourier transform spectrometer

Sugar composition and sugar-related parameters of honeys from the northern Iberian Plateau

Novel biphenyldiylbis(oxazoline) and both racemic and optically active and binaphthyldiylbis(oxazolines) (1−4) have been cationically cyclopolymerized to give polymers that contained pendent heteromacrocyclic metal receptors. The optically active cyclopolymers showed very high specific optical rotations per repeat unit that varied between [α −248° and [α −321° depending upon the solvent. Circular dichroism spectra and optical rotation showed dependence on molecular weight. The cyclopolymers are thermally robust with decomposition temperatures >400 °C and glass transition temperatures (Tg) between 200 and 302 °C. The polymers were reduced with AlH3 to give polymers with pendent nitrogen-containing heteromacrocycles. Dichloromethane solutions of the reduced polymers were used to extract Cu(NO3)2 from aqueous solutions to give complexes whose stoichiometry varied from 3−4 Cu2+ ions per five reduced repeating units. The Cu2+-containing cyclopolymers gave higher Tg (100−180 °C) than obtained for the reduced polymers (72−138 °C) which in turn gave much lower Tg than did the corresponding unreduced polymers.

This study presented a straightforward method for detecting the adulteration of natural bee honey with consumable artificial honey and bee syrups. The approach, based on measuring alkali and alkaline earth metal content, revealed that adulterated honey samples had lower K, Rb, Mg, and Ca levels and elevated Na content. A novel and cost-effective method, solution cathode glow discharge optical emission spectrometry (SCGD OES), was developed for elemental analysis. The method's trueness was confirmed through ICP OES and ICP MS measurements. SCGD OES featured excellent measurement precision (<1%) with low limits of detection, i.e., 0.005, 0.007, 0.015, 0.2, and 20μgL-1 for Na, K, Rb, Mg, and Ca, respectively. It surpassed commercial techniques with lower costs, straightforward sample preparation (no acid digestion needed), and a simplified setup. The average detection threshold for adulteration was 21%, 13%, and 12% for rapeseed, goldenrod, and honeydew honey, respectively.

We report a new, to the best of our knowledge, measurement method of optical rotatory dispersion (ORD) based on a polarization axis finder (PAF) and digital image processing. The collimated quasi-monochromatic light is output by a monochromator and passes through a polarizer and the chiral samples, and a PAF is employed to modulate the light beam spatially to form an "hourglass" intensity pattern, which is utilized to determine the polarization direction of linearly polarized light. After being recorded by a digital camera, the modulated patterns with and without samples are analyzed by our specially designed digital image processing program to calculate the optical rotation (OR) angle of the chiral substance at a certain wavelength, and the ORD curve can be obtained by fitting a series of OR angles with different wavelengths. The ORD curves of two standard quartz plates with opposite chirality and a glucose solution with different concentrations are measured experimentally, and the fitted coefficients and measurement results agree well with their theoretical values, which indicates that the presented method is an effective and accurate way to determine the ORD of chiral substances conveniently.

Saturation d'activite optique par lumiere laser intense

It has been demonstrated that using two-mode squeezed vacuum state for phase estimation can break the Heisenberg limit. Our results reveal that the two-mode squeezed vacuum state is also applied to the optical rotation angle measurement. In our scheme, the resolution and sensitivity of the optical rotation angle signal are the same as the case of phase estimation. For the parameter estimation, phase or rotation angle, we discuss the influences of several imperfect factors on the resolution and sensitivity. First, the effect that the upper limit of photon-number resolving has on the maximum amount of available quantum Fisher information has been analyzed. Then, we have also studied the impacts of both the transmission efficiency in the transmission process and the detection efficiency on the detection results. Finally, conditions where all of the above imperfect elements are taken into account at the same time have also been explored. Additionally, other imperfect factors such as squeezing efficiency and dark counts are briefly discussed.

An instrument for measuring low optical rotation angle

Studies on the conformational transformations of l-arginine molecule in aqueous solution with temperature changing by circular dichroism spectroscopy and optical rotations

Adulteration identification of some fungal polysaccharides with SEM, XRD, IR and optical rotation: A primary approach

In order to correct the errors present in our recent study (Savaryn V. et al.Ukr.J. Phys.Opt. 13 (2012) 82), we have rederived the main phenomenological relations describing the changes in optical anisotropy of crystalline disks loaded along their diameters.Basing on the analysis of these relations, we have developed an improved technique for determining the piezooptic coefficients 44  , 55  and 66 for the crystals of almost all of the point symmetry groups.The technique is based on studying the spatial distributions of optical birefringence and optical indicatrix rotation angle induced along the chords and diameters of a crystalline disk compressed along its diameter.

Three different chiroptical spectroscopic methods, namely, optical rotation, electronic circular dichroism (ECD), and vibrational circular dichroism (VCD) have been evaluated for studying the aggregation of sodium dodecylsulfate (SDS), an achiral surfactant, using garcinia acid disodium salt (GADNa) as a chiral probe. The specific rotation and ECD of GADNa are found to be altered by the aggregation of SDS, suggesting for the first time that achiral surfactants can be characterized with chiroptical spectroscopy using appropriate chiral probes. In addition, a chiral compound, fluorenyl methyloxy carbonyl l-leucine sodium salt (FLNa) is found for the first time to behave as a surfactant in water, with 205 Å(2) surface area per molecule at the air-water interface, critical micelle concentration (CMC) of 0.18 M, and Gibbs energy of micellization of -14 kJ/mol. The specific rotation of FLNa in water is found to increase with concentration beyond CMC, suggesting the formation of chiral aggregates. Different conformations of FLNa amenable to micellization have been identified using quantum chemical conformational analysis and their specific rotations calculated. The formation of lamellar aggregates of FLNa in water is suggested to be the cause for increase in specific rotation with concentration beyond CMC.