Analytical applications of polarimetry, optical rotatory dispersion, and circular dichroism

Purdie, Neil; Swallows, Kathy A.

doi:10.1021/ac00177a001

Cited by 29 publications

(15 citation statements)

References 14 publications

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“…Finally in Step 5, we linearly interpolate the differential phase spectrum to k to obtain an estimate of −1.0471100 rad for the phase difference between the signals. This compares to the 'true' phase difference of − / 3 1 0471976 π = − . rad -a difference of 8.7548e × 10 −5 rad or 0.005°.…”

Section: Consider a Digitised Functionmentioning

confidence: 82%

A high-resolution polarimeter formed from inexpensive optical parts

Harvie¹,

Phillips

deMello³

2020

Sci Rep

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We describe a high resolution laser polarimeter built from commodity optical components. the optical rotation angle is determined by measuring the phase difference between two harmonically modulated polarised laser beams-an 'object beam' that passes through the sample under test and a 'reference beam' that bypasses the sample. The complete polarimeter may be assembled from low cost off-the-shelf parts for less than £300 (UK Sterling). Data acquisition and analysis are carried out on a microcontroller running an efficient algorithm based on the sliding Discrete Fourier Transform. Despite its low cost, the polarimeter is a fully automatic, research-grade instrument with an accuracy of ±0.0013° and a precision of ±0.0028°-comparable to far costlier commercial instruments. The polarimeter's ease of use, compact size, fast measurement times and high angular resolution make it a capable and versatile tool for analytical science, while its low cost means it is ideally suited for use in resource-constrained environments and process monitoring. the polarimeter is released here as open hardware, with technical diagrams, a full parts list, and source code for its firmware included as Supplementary information. The tremendous advances in electronic hardware over recent decades have led to substantial improvements in the speed, accuracy, precision and functionality of scientific instrumentation. The electromechanical automation of intricate physical and chemical procedures, the development of brighter and more stable light-sources, the proliferation of low-noise sensors, improvements in amplifier technology, and the availability of better signal processing and data analysis techniques (to name but a few) have all contributed positively to analytical performance. Taking the subject of this manuscript-polarimetry-as an example, virtually all polarimeters in the early 1960s were manually operated instruments with hand-rotated analysers and telescopic eye-pieces that relied on human judgement to determine the angle of rotation. Today, they are motorised instruments with integrated photodetectors that automatically measure optical rotation angles at the push of a button. However, while functionality has improved tremendously over the past fifty years, equipment costs have changed very little: in 1965, a manually

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Section: Consider a Digitised Functionmentioning

confidence: 82%

A high-resolution polarimeter formed from inexpensive optical parts

Harvie¹,

Phillips

deMello³

2020

Sci Rep

View full text Add to dashboard Cite

show abstract

“…No real-time, full-spectrum CD detectors are currently available for HPLC, but one would not be beyond development if the need arose [163]. Conventional CD, like conventional polarimetry, is not sensitive enough for HPLC use.…”

Section: Circular Dichroismmentioning

confidence: 99%

“…The first, by Purdie and Swallows [163], discusses both conventional and on line applications of OA detection. The first, by Purdie and Swallows [163], discusses both conventional and on line applications of OA detection.…”

Section: A Introductionmentioning

confidence: 99%

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Other Modes of Detection

Parriott

1993

A Practical Guide to HPLC Detection

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“…They are essential analytical tools in many fields including pharmaceuticals, food, cosmetics and chemicals. 1 Conventional polarimeters work by aiming a vertically polarised laser beam at a horizontally oriented polariser which blocks the incident light. Placing an optically active sample in the path of the laser beam causes the polarisation axis of the beam to rotate, allowing some of the laser light to leak through the polariser.…”

Section: Introductionmentioning

confidence: 99%

The Open Polarimeter: A High-Resolution Instrument Made from Inexpensive Optomechanical Parts

Harvie¹,

Mello

2020

Preprint

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The Open Polarimeter (“Opol”) is a phase-based, high-resolution laser polarimeter formed from a small number of inexpensive optomechanical parts. The complete instrument can be assembled from scratch in two days for less than US$250, using only a 3D-printer and a benchtop milling machine. However despite its low cost Opol achieves a high accuracy of a few millidegrees, comparable to far costlier commercial instruments. It is released here as open hardware, with technical diagrams, a full parts list, and source-code for its firmware included as Supporting Information. Beyond polarimetry, Opol’s easy-to-build and versatile optical mounting system is likely to prove useful for a wide variety of optical systems.

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Analytical applications of polarimetry, optical rotatory dispersion, and circular dichroism

Cited by 29 publications

References 14 publications

A high-resolution polarimeter formed from inexpensive optical parts

A high-resolution polarimeter formed from inexpensive optical parts

Other Modes of Detection

The Open Polarimeter: A High-Resolution Instrument Made from Inexpensive Optomechanical Parts

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