Simultaneous, sequential quantitative achiral–chiral analysis by two‐dimensional liquid chromatography

Abstract

In general, chromatographic analysis of chiral compounds involves a minimum of two methods; a primary achiral method for assay and impurity analysis and a secondary chiral method for assessing chiral purity. Achiral method resolves main enantiomeric pairs of component from potential impurities and degradation products and chiral method resolves enantiomeric pairs of the main component and diastereomer pairs. Reversed-phase chromatographic methods are preferred for assay and impurity analysis (high efficiency and selectivity) whereas chiral separation is performed by reverse phase, normal phase, or polar organic mode. In this work, we have demonstrated the use of heart-cutting (LC-LC) and comprehensive two-dimensional liquid chromatography (LC × LC) in simultaneous, sequential achiral and chiral analysis and quantitation of minor, undesired enantiomer in the presence of major, desired enantiomer using phenylalanine as an example. The results were comparable between LC-LC and LC × LC with former offering better sensitivity and accuracy. The quantitation range was over three orders of magnitude with undesired D-phenylalanine detected at approximately 0.3% in the presence of predominant, desired L-phenylalanine (99.7%). The limit of quantitation was comparable to conventional high-performance liquid chromatography. A reversed-phase C18 achiral column in the primary and reversed-phase Chirobiotic Tag chiral column in the secondary dimension were used with a compatible mobile phase.

Wine science in the metabolomics era

“…Its application to authenticity and traceability of wines has not yet been reported, despite its great potential (e.g., simultaneous achiral and chiral separations) [89,90].…”

Assessing stability-indicating methods for coelution by two-dimensional liquid chromatography with mass spectrometric detection

“…This is a simpler approach compared to finding complementary columns as they are hard to find for structurally similar compounds in RP separation. Also, this work reiterates the advantages of parallel columns in the secondary dimension as discussed in our earlier work [32][33][34][35][36].…”

“…In general, the off-line approach will be simpler and a better alternative to the online approach with multiple secondary columns and complicated synchronized multiple switching valves. An exception to this rule is the resolution of coeluting chiral components using 2D-LC with an achiral primary column and chiral secondary column as demonstrated in our previous work [32,33]. The minor enantiomer was detected at levels <0.25%.…”

Identification of l‐carnitine and its impurities in food supplement formulations by online column‐switching liquid chromatography coupled with linear ion trap mass spectrometry

“…Two‐dimensional HPLC can significantly increase the resolving power and achieve separations that cannot be obtained by 1D separation. Two‐dimensional HPLC has been reported extensively in the analysis of biological samples , proteomics , and natural products . We have also developed an off‐line 2D HPLC MS method for proteomics analysis .…”