Detection of Chiral Compounds Using HPLC with CD Detection
Chiral detectors provide valuable information since
Experimental
they only respond to optically active compounds. This
Compounds were run on a Jasco HPLC equipped with
allows the researcher to differentiate enantiomers. A
a CD and an ORD detector. Sensitivity comparisons
sensitivity comparison between the two chiral detection
were based on quantitation limits for each compound
techniques optical rotation (ORD) and circular
dichroism (CD) was conducted with a variety of
compounds to demonstrate the effectiveness of the techniques.
Table I: Comparison of ORD and CD Detectors: Quantitation limits of analytess (S/N=10). Introduction
Chiral separation has become one of the most
OR (ug) CD (ug) Increase
important applications of HPLC. Chiral analysis has
Flavanone 7.4 0.05 148X
become critical in drug development because in many
Triadimefon 6.9 0.09 77X
cases like thalidomide one enantiomer has health
t-Stillbene oxide 1.2 0.11 11X
benefits while the other is toxic or mutagenic. Chiral
Naproanilide 6.3 0.36 18X
detection has previously been limited to optical rotary
Pindolol 33.6 0.56 60X
dispersion (ORD) or polarimetry. Optical rotation-based
Indapamide 20.6 0.62 33X
detectors are based on differences in refractive index.
Ibuprofen 23.9 1.04 23X
Circular dichroism-based detectors differentiate
Flubiprofen 30.4 1.38 22X
enantiomers by measuring differences between the
absorption of right and left-handed circularly polarized
Conclusions
light. These detectors provide higher sensitivity and a
The circular dichroism based chiral detector typically
stable signal which is not affected by gradient analysis.
provides sensitivity 10-100x greater than optical
rotation-based chiral detectors. This provides highly sensitive and selective detection of chiral compounds that have a UV absorption in the 220-420 nm range. The CD detector also provides a UV signal in addition to the CD signal. This allows optical purity determinations without chiral separation. CD detection is also unaffected by gradient elutions or other changes in non-chiral components during elution. Detection of chiral compounds can be done with or without prior chiral separation using the CD detector. Polarimetric or optical rotation-based detectors remain a viable alternative for compounds that do not contain a chromophore by allowing universal detection with reduced sensitivities. These detectors can still be used for the majority of chiral compounds and are excellent for sugars. Jasco is currently the only manufacturer capable of providing chiral detectors based on both of
these techniques as well as many other HPLC
Figure 1. Chiral separation of 10µg of ibuprofen. Contact: Jasco, Inc. 8649 Commerce Dr. Easton, MD 21601 800-333-5272 Fax: 410-822-7526 www.jascoinc.com
Thirteenth Sermon on 2 Thessalonians Chapter Two Therefore, brethren, stand fast, and hold the traditions which ye have beentaught, whether by word, or our epistle.—2 Thes. 2:15. HE apostle, after he had comforted the Thessalonians, he exhorteth them toconstancy in the truth, whatever temptations they had to the contrary. TheTcomforts he propoundeth to them were taken—(1.) From the
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