Enhanced Polarimetric Detection in HPLC Using a Refractive Index Equalizer

Maystre, F.; Bruno, Alfredo E.; Kuehner, Christian.; Widmer, Hans

doi:10.1021/ac00090a014

Cited by 8 publications

(8 citation statements)

References 8 publications

(1 reference statement)

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“…Fluid RI changes are often a major source of interference in the measurement of optical activity. ,, In our initial qualitative observations of the CPD, the position and relative spacing of the high-frequency fringes are found to be insensitive to small RI changes. To prove this observation, we mapped the fringes upon injecting solutions of from 0.01% to 0.07% glycerol into the capillary.…”

Section: Resultsmentioning

confidence: 76%

“…Although this technique is powerful, Tran and co-workers employed a somewhat complex optical configuration that is not well suited to miniaturization or flow cell volume reduction. In another effort to improve polarimetric detection capabilities, Mayster and co-workers coupled a refractive index detector to a conventional polarimeter for “equalization” and performance enhancement. A standard flow cell with a volume of 40 μL is employed in this “two-for-one” detector configuration.…”

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confidence: 99%

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Polarimetry in Capillary Dimensions

Bornhop

Hankins

1996

Anal. Chem.

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Microinterferometeric backscatter is employed to detect optically active molecules in capillary tubes. The capillary polarimetric detector (CPD) is based on the interaction between a polarized laser beam and a capillary tube. The simple optical configuration employs a He−Ne laser, a glass polarizing plate, a fused silica tube, and a CCD-based laser beam analyzer. Side illumination of the capillary produces a 360° fan of scattered light that contains two sets of high-contrast interference fringes. These light and dark spots are viewed on a flat plane in the direct backscatter configuration. It is shown that the modulation depth for the high-frequency component is sensitive to the polarization plane for the illumination source and facilitates the quantitative determination of optical activity for a fluid contained in a capillary. A 90° rotation of exciting plane-polarized light results in a depth of modulation change of ∼80% when unmodified capillaries ranging from 75 to 530 μm i.d. are employed. Signal interrogation in the CPD is based on quantifying the relative intensities (depth of modulation) of adjacent high-frequency interference fringes. Mandelic acid, [α]23 of −153°, is used as the optically active molecule and can be detected at a 2σ detection limit of 1.49 × 10-3 M within a probe volume of about 30 nL. This limit of detection corresponds to 44 pmol or 6.7 ng of mandelic acid. The folded optical arrangement is simple and can be miniaturized with low-cost components. Initial investigations suggest that the CPD can be employed for detection in capillary electrophoresis or for studying the onset and level of solute aggregation.

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Section: Resultsmentioning

confidence: 76%

mentioning

confidence: 99%

Polarimetry in Capillary Dimensions

Bornhop

Hankins

1996

Anal. Chem.

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“…Using this system, 3 they reported detection levels of 1.5 3 10 2 6 degrees, which correspond to m ass detection limits of 12 ng. Mayster and co-workers 4 took a different approach and enhanced the performance of a conventional polarimeter by ''equalization'' through coupling a refractive index detection arm to the polarimetry sensor. This system required a sample volume of 40 mL in order to m easure optical rotation values of solutes with low speci c rotations.…”

Section: Introductionmentioning

confidence: 99%

Nanoliter Volume Polarimetry

2002

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“…Many attempts have been made to incorporate polarimetry detection with small volume analysis. Such attempts include the work of Yeung et al 2,3 and Mayster et al 4 PDR-CHIRAL 5 have made the most recent advance in developing a small volume polarimeter, which appears to be a commercial variation of Yeung's previous work. 2 This system has been shown to have detection limits at the 10 mM level for most solutes when employed as a detector for high performance liquid chromatography.…”

Section: Introductionmentioning

confidence: 99%

Capillary-scale polarimetry for flowing streams

Swinney

Nodorft

Bornhop

2001

Analyst

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A micro-polarimeter with a 40 nL probe volume was configured so that it is compatible with capillary-scale flowing stream analysis. The optical configuration consists of two polarizing optics, a capillary, a laser source and a photodetector which is very simple to configure with low cost components. This unique polarimeter is based upon the interaction of a linearly polarized laser beam and a capillary tube, in this case one with an inner diameter of 250 microns. Side illumination of the tube results in a 360 degrees fan of scattered light, which contains a set of interference fringes that change in response to optically active solutes. Solutes that exhibit optical activity are quantifiable and are detected by analyzing the polarization state of the backscattered light. The ability of the instrument to make extremely sensitive optical activity measurements in flowing streams is shown by the determination of (R)-mandelic acid, with a detection limit of 66 x 10(-6) M (507 x 10(-12) g), and the non-optically active control, glycerol. Additionally, the detector was configured to minimize refractive index perturbations.

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Enhanced Polarimetric Detection in HPLC Using a Refractive Index Equalizer

Cited by 8 publications

References 8 publications

Polarimetry in Capillary Dimensions

Polarimetry in Capillary Dimensions

Nanoliter Volume Polarimetry

Capillary-scale polarimetry for flowing streams

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