Polarimetric Detection Research Articles

Enantiomerization during HPLC on an optically active sorbent. Deconvolution of experimental chromatograms

The enantiomers of 1,3,7-trimethylbenzo[c]phenanthrene, a chiral helicene hydrocarbon, are separated on triacetyl-cellulose but interconvert during HPLC. Column temperatures were between 2 and 22°C and linear velocities between 0.3 and 1.2 mm s−1. Simultaneous photometric and polarimetric detection resulted in deconvoluted experimental chromatograms, showing the relative concentration of each of the enantiomers as aseparate function of the retention volume. The use of deconvoluted chromatograms for determining rate constants of enantiomerization is discussed. It is of interest that the rate constant at 22.3°C in solution, i.e. in the absence of a sorbent, has been obtained by an independent method: stopped-flow monitoring of racemization after HPLC on triacetylcellulose.

Studies of target detection algorithms that use polarimetric radar data

Algorithms are described which make use of polarimetric radar information in the detection and discrimination of targets in a ground clutter background. The optimal polarimetric detector (OPD) is derived. This algorithm processes the complete polarization scattering matrix (PSM) and provides the best possible detection performance from polarimetric radar data. Also derived is the best linear polarimetric detector, the polarimetric matched filter (PMF), and the structure of this detector is related to simple polarimetric target types. New polarimetric target and clutter models are described and used to predict the performance of the OPD and the PME. The performance of these algorithms is compared with that of simpler detectors that use only amplitude information to detect targets. The ability to discriminate between target types by exploring differences in polarimetric properties is discussed. >

Polarimetric detection in high-performance liquid chromatography.

Chiroptical detection for HPLC is particularly useful as a selective detection method for chiral molecules, and in enantiomeric purity determination with partial chiral separation or without chiral separation. The recent development of laser-based polarimeters with microdegree sensitivity has increased the applicability of optical rotation detection in HPLC. The detection limit of these instruments is submicrogram on-column for many chiral compounds in analytical HPLC. A variety of applications of the selective detection of optically active molecules are reviewed. The use of polarimetric detection with partial chiral separation is considered, both as an aid to method development and for enantiomeric purity determination. Finally applications to enantiomeric purity determination without chiral separation are reviewed, with the dual use of nonchirally selective and chiroptical detectors to determine the total amount and optical purity of the analyte. Determinations of chiral purity for samples of high enantiomeric excess are described, which with laser-based instrumentation may give accuracies of better than +/- 1% with sample loadings of 50 micrograms on an achiral column. Applications to the study of enantioselective reactions are also considered, with determination of enantiomeric excess in near-racemates to better than +/- 0.1%.

Improvements in the qualitative and quantitative study of erythromycins using laser-based polarimetric detection

A technique in which liquid chromatographic separation is combined with laser-based polarimetric detection is described for the study of erythromycin and its analogs. The polarimetric system, owing to the inherent selectivity of the technique, can provide unique advantages, particularly when the measurement must be made in a complicated matrix. Individual specific rotations have been measured for the three erythromycin analogs A, B and C and for the derivative erythromycin ethylsuccinate (EES). The results suggest that specific rotation may be used to identify closely related erythromycin species in studies of their fate and location in physiological pathways. The detection limit for the technique is 12 ng for erythromycin and 10 ng for EES. The distinct advantages of this technique, in terms of both sensitivity and selectivity, are demonstrated by the determination of erythromycin in milk and EES in a pharmaceutical preparation.

Chiroptical detection. Novel possibilities of its application to enantiomers

Polarimetric and/or circular dichroic detection of enantiomers after liquid chromatography on optically active sorberts has been used for the following purposes: determination of enantiomeric purity in spite of peak overlap, investigation of enantiomerization during chromatography, monitoring of racemizations and recording of circular dichrograms without preparative enrichment of enantiomers. Novel examples for all applications are give. The general prospects for chiroptical detection are discussed.

Separation and identification of enantiomers by high-performance liquid chromatography with a chiral column and a polarimetric detector as applied to deltamethrin

Separation and identification of enantiomers by high-performance liquid chromatography with a chiral column and a polarimetric detector as applied to deltamethrin

Detectors for liquid chromatography

Refractive Index Detector Absorption Detectors for High-Performance Liquid Chromatography FTIR Detection Indirect Absorbance Detectors Fluorometric Detection Polarimetric Detectors Detection Based on Electrical and Electrochemical Measurements Mass Spectrometry as an On-Line Detector for HPLC Miscellaneous Methods Index.

Improvements in Detectabilities in Polarimeters Using High-Frequency Modulation

The change in the plane of polarization of light can be an important experimental parameter in many spectroscopic determinations, as in, for example, polarization spectroscopy and the Raman-induced Kerr effect. Also, polarimetric detection, in conjunction with high-performance liquid chromatography (HPLC), has been used to investigate sugars in urine, cholesterol in blood, and the chiral components of fossil fuels. Recent work has demonstrated the utility of converting the very selective polarimetric detector to a universal one. Additionally, the same system can be used to simultaneously detect analyte absorptions with excellent sensitivity.

Improved noninvasive ‘fibredyne’ highway based on polarimetric detection of strain in polarisation-maintaining fibres

The letter reports a novel configuration of a noninvasive fibredyne highway, which has greatly improved optical efficiency, no need for a separate reference fibre and freedom from polarisation fading. Using a compensated polarimetric configuration, it can be used with semiconductor laser sources of relatively short coherence length. A received carrier/noise ratio of 55 dB has been achieved at 10 MHz with a 30 kHz bandwidth.

Spectrophotometric and polarimetric detectors in liquid chromatography for the determination of enantiomer ratios in complex mixtures

Spectrophotometric and polarimetric detectors in liquid chromatography for the determination of enantiomer ratios in complex mixtures

Liquid chromatography of sugars on silica-based stationary phases

A review is given of sugar analysis by liquid chromatography using silica columns. Aspects covered are column materials and preparation, chemically and physically modified amine columns, octadecy- and unmodified silica columns; eluent composition and elution mechanisms for the different types of columns used; detection methods, RI and UV detectors, visible lights, fluorescence, moving-wire, polarimetric and mass detection; and sample preparation and origin of samples.

Determination of the relative amounts of the b and c components of neomycin by ion-exclusion chromatography using refractometric detection

Refractometric detection can be used as a convenient alternative to ninhydrin colorimetric or polarimetric detection in ion-exclusion chromatography of neomycin. The determination of the relative amounts of neomycin B and C using different detection methods is examined. The use of a resin of smaller granulometry and a medium-pressure chromatographic apparatus reduces the analysis time to less than 25 min.

Polarimetric Detection Method of Lunar Luminescence.

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Polarimetric Detection Method of Lunar Luminescence. Gehrels, T. Abstract Luminescence was detected photometrically and it was independently confirmed by polarization measurements. Three lunar regions were observed in April 1959 and again in November 1963; (Il-I2)/(Ii+I2) differed systematically. Assuming the luminescence is not polarized it subtracts out in (I, -12) but not in (11+12). In 1956/59 the lunar surface was 10-20% brighter than in 1963 November/1964 January. The effect is fairly constant from day ~o day, with a few notable exceptions, while it presumably depends on the solar cycle (Gehrels, T., Coffeen, T., and Owings, D., unpublished). Publication: The Astronomical Journal Pub Date: 1964 DOI: 10.1086/109394 Bibcode: 1964AJ.....69Q.542G full text sources ADS |