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Burk RJ, Wahab MF, Armstrong DW. Influence of theoretical and semi-empirical peak models on the efficiency calculation in chiral chromatography. Talanta 2024; 277:126308. [PMID: 38820823 DOI: 10.1016/j.talanta.2024.126308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Revised: 05/13/2024] [Accepted: 05/20/2024] [Indexed: 06/02/2024]
Abstract
Height equivalent to theoretical plate (H) equations, such as the van Deemter or Knox-Saleem equations, and other efficiency vs. linear velocity equations (u), provide kinetic insights into chromatographic separations phenomena and column performance. In enantioselective separations, the peak shape of the two enantiomers can differ significantly and are often asymmetric. The peak efficiency calculations heavily impact these efficiency-flow profiles, leading to erroneous estimations of eddy diffusion, longitudinal diffusion, and mass transfer terms. In this work, new asymmetric peak functions are employed for modeling enantiomer peaks based on the Haarhoff-Van der Linde function, its generalized variant (GHVL), once Generalized Asymmetric Gaussian (AGN), and Twice Generalized Gaussian (TGN). The new models (AGN, TGN, and GHVL) incorporate higher statistical moments besides the zeroth, first, and second moments to account for two-sided asymmetry (fronting or tailing). The fit results are compared with the traditional efficiency calculation methods endorsed by official pharmacopeia and numerical estimation of moments from the raw data. Enantiomeric separations of ibuprofen and dl-homophenylalanine were chosen as probe molecules. The results demonstrate that non-linear least squares fitted functions provide better estimations of peak efficiency data even in the presence of high noise. In particular, the generalized models consistently offered the best quality fits for various peak shapes in chiral separations. Conversely, the half-height Gaussian method greatly overpredicted skewed peak efficiencies. This investigation reveals that the commonly held assumptions of peak shape and numerical integration of raw data are highly insufficient for chiral chromatography. The impact of asymmetry on plate height should not be overlooked when accurate data from efficiency-flow rate curves is derived. We advocate for the broader adoption of these new generalized peak (AGN, TGN, GHVL) models because they provide robustness at various SNRs that account for right or left asymmetry while accurately representing peak geometry.
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Affiliation(s)
- Ryan Jacob Burk
- Department of Chemistry & Biochemistry, University of Texas at Arlington, Texas, 76019, USA
| | - M Farooq Wahab
- Department of Chemistry & Biochemistry, University of Texas at Arlington, Texas, 76019, USA.
| | - Daniel W Armstrong
- Department of Chemistry & Biochemistry, University of Texas at Arlington, Texas, 76019, USA.
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Li F, Knappe C, Carstensen N, Favorat E, Gao M, Holkenjans W, Hetzel T, Pell R, Lämmerhofer M. Two-dimensional sequential selective comprehensive chiral×reversed-phase liquid chromatography of synthetic phosphorothioate oligonucleotide diastereomers. J Chromatogr A 2024; 1730:465076. [PMID: 38879975 DOI: 10.1016/j.chroma.2024.465076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 06/04/2024] [Accepted: 06/10/2024] [Indexed: 06/18/2024]
Abstract
In recent years, many nucleic acid-based pharmaceuticals have been approved and entered the market, and even a larger number are in late stage clinical trials. Conventional oligonucleotides are facing issues in vivo like fast renal clearance and nuclease degradation. Therefore, to increase their stability, phosphorothioation is a frequent modification of therapeutic oligonucleotides (ONs) which also leads to improved binding affinity facilitating cell internalization and intracellular distribution. At the same time, by replacing a phosphodiester linkage with a phosphorothioate group, a phosphorous stereogenic center is generated which causes the formation of Rp- and Sp-diastereomers. It increases the structural diversity. For example, with 15 of those phosphorothioate (PS) linkages, 32,768 different diastereomers are expected. Since the phosphorothioate is introduced non-stereoselectively, the molecular complexity of the resultant phosphorothioate ON products is tremendously increased impeding the chromatographic separation in the course of quality control. Since distinct phosphorothioate diastereomers have different bioactivities and pharmacological properties, there is increasing interest in implications of stereoisomerism of phosphorothiate oligonucleotides. From a quality and regulatory viewpoint, batch-to-batch reproducibility of the diastereomer profile may be of significant concern. In order to address this issue, this study investigates the stereoselectivity of LC methods for two phosphorothioate oligonucleotide (PSO) compounds differing in their molecular size and numbers of PS linkages. Diastereoselectivity of ion-pairing reversed-phase liquid chromatography (IP-RPLC), RPLC without ion-pairing agents and LC with chiral polysaccharide-based column were evaluated for model PSOs and an active pharmaceutical ingredient (API) of PSO with trivalent N-acetylgalactosamine (GalNAc) conjugate. Due to the structural complexity of PSOs, the separation power for the diastereomer mixture was increased by using sequential selective comprehensive two-dimensional chromatography with an amylose tris(α-methylbenzylcarbamate)-immobilized chiral stationary phase (CSP) in the first dimension and ion-pair RPLC with ethylammonium acetate in the second dimension. Improved diastereomer selectivity was obtained and a larger number of peaks could be separated.
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Affiliation(s)
- Feiyang Li
- Institute of Pharmaceutical Sciences, Pharmaceutical (Bio-)Analysis, University of Tübingen, Auf der Morgenstelle 8, 72076 Tübingen, Germany
| | - Cornelius Knappe
- Institute of Pharmaceutical Sciences, Pharmaceutical (Bio-)Analysis, University of Tübingen, Auf der Morgenstelle 8, 72076 Tübingen, Germany
| | - Niklas Carstensen
- Institute of Pharmaceutical Sciences, Pharmaceutical (Bio-)Analysis, University of Tübingen, Auf der Morgenstelle 8, 72076 Tübingen, Germany
| | - Enrico Favorat
- Institute of Pharmaceutical Sciences, Pharmaceutical (Bio-)Analysis, University of Tübingen, Auf der Morgenstelle 8, 72076 Tübingen, Germany
| | - Mimi Gao
- Bayer AG, Pharmaceutical Division, Friedrich-Ebert-Strasse 217-333 42117 Wuppertal, Germany
| | - Wiebke Holkenjans
- Bayer AG, Pharmaceutical Division, Friedrich-Ebert-Strasse 217-333 42117 Wuppertal, Germany
| | - Terence Hetzel
- Bayer AG, Pharmaceutical Division, Friedrich-Ebert-Strasse 217-333 42117 Wuppertal, Germany
| | - Reinhard Pell
- Bayer AG, Pharmaceutical Division, Friedrich-Ebert-Strasse 217-333 42117 Wuppertal, Germany
| | - Michael Lämmerhofer
- Institute of Pharmaceutical Sciences, Pharmaceutical (Bio-)Analysis, University of Tübingen, Auf der Morgenstelle 8, 72076 Tübingen, Germany.
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Stoll D, Sylvester M, Meston D, Sorensen M, Maloney TD. Development of multiple heartcutting two-dimensional liquid chromatography with ion-pairing reversed-phase separations in both dimensions for analysis of impurities in therapeutic oligonucleotides. J Chromatogr A 2024; 1714:464574. [PMID: 38103311 DOI: 10.1016/j.chroma.2023.464574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 12/02/2023] [Accepted: 12/09/2023] [Indexed: 12/19/2023]
Abstract
Oligonucleotides constitute an emerging and highly complex bioanalytical challenge and it is becoming increasingly clear that 1D methodologies are unable to fully resolve all possible impurities present in these samples. 2D-LC therefore constitutes a perfect solution wherein critical pairs can be sampled from a steep gradient 1D and separated in a shallower 2D gradient. Herein, we provide a facile 2D-LC method development approach to quickly generate high selectivity gradients utilizing ion pairing reverse phase (IPRP-IPRP). In particular we demonstrate how to iteratively generate a 12 % gradient from two training runs and then to utilize that data to predict retentions of analytes with a 2 % gradient with retention prediction errors as low as 3 and 11 %, respectively. This iterative method development workflow was applied to impurity profiling down to 1:1000 for the full-length product and phosphorothioate modified impurities. Additionally, we demonstrated the elucidation of critical pairs in complex crude pharmaceutical oligonucleotide samples by applying tailored high selectivity gradients in the second dimension. It was found that the iterative retention modeling approach allows fast and facile 2D-LC method development for complex oligonucleotide separations.
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Affiliation(s)
- Dwight Stoll
- Department of Chemistry, Gustavus Adolphus College, Saint Peter, MN 56082, USA.
| | - Maria Sylvester
- Department of Chemistry, Gustavus Adolphus College, Saint Peter, MN 56082, USA
| | - Daniel Meston
- Department of Chemistry, Gustavus Adolphus College, Saint Peter, MN 56082, USA
| | - Matt Sorensen
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA
| | - Todd D Maloney
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA
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Lippens JL, Timmons HC, Welch C, Kulkarni A, Flick TG. Rapid Intact Mass Analysis and Evaluation of the Separation Potential of Microfluidic Capillary Electrophoresis Mass Spectrometry for Oligonucleotides. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2023; 34:2491-2497. [PMID: 37823612 DOI: 10.1021/jasms.3c00217] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
Oligonucleotide characterization is a rapidly advancing field in the biopharmaceutical industry. Understanding critical quality attributes, such as intact mass and impurities, requires a toolbox of analytical techniques, which commonly includes liquid chromatography-mass spectrometry (LC-MS). Oligonucleotide LC-MS analysis frequently requires sample run times upward of 15 min to achieve separation of multiple oligonucleotide species. Additionally, LC methods frequently employ mobile phase additives such as triethylamine and 1,1,1,3,3,3-hexafluoro-2-propanol that are not always desired for use in MS instrumentation. Here, microfluidic capillary electrophoresis mass spectrometry (CE-MS) via ZipChip technology was employed to enable rapid intact mass analysis of oligonucleotide single strands. Baseline separation of equal length oligonucleotides was achieved in less than 4 min. Additionally, the potential of the ZipChip platform for separation of oligonucleotide full-length products (FLPs) and their impurities was evaluated.
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Affiliation(s)
- Jennifer L Lippens
- Pivotal Attribute Sciences, Amgen, Thousand Oaks, California 91320, United States
| | - Heath C Timmons
- Pivotal Attribute Sciences, Amgen, Thousand Oaks, California 91320, United States
| | - Crystal Welch
- 908 Devices, Boston, Massachusetts 94720-1460, United States
| | - Aditya Kulkarni
- 908 Devices, Boston, Massachusetts 94720-1460, United States
| | - Tawnya G Flick
- Pivotal Attribute Sciences, Amgen, Thousand Oaks, California 91320, United States
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Fekete S, Guillarme D. Ultra-short columns for the chromatographic analysis of large molecules. J Chromatogr A 2023; 1706:464285. [PMID: 37562104 DOI: 10.1016/j.chroma.2023.464285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 07/31/2023] [Accepted: 08/04/2023] [Indexed: 08/12/2023]
Abstract
Today, reverse phase liquid chromatography (RPLC) analysis of proteins is almost exclusively performed on conventional columns (100-150 mm) in gradient elution mode. However, it was shown many years ago that large molecules present an on/off retention mechanism, and that only a very short inlet segment of the chromatographic column retains effectively the large molecules. Much shorter columns - like only a few centimetres or even a few millimetres - can therefore be used to efficiently analyse such macromolecules. The aim of this review is to summarise the historical and more recent works related to the use of very short columns for the analysis of model and therapeutic proteins. To this end, we have outlined the theoretical concepts behind the use of short columns, as well as the instrumental limitations and potential applications. Finally, we have shown that these very short columns were also possibly interesting for other chromatographic modes, such as ion exchange chromatography (IEX), hydrophilic interaction chromatography (HILIC) or hydrophobic interaction chromatography (HIC), as analyses in these chromatographic modes are performed in gradient elution mode.
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Affiliation(s)
| | - Davy Guillarme
- Institute of Pharmaceutical Sciences of Western Switzerland, University of Geneva, CMU - Rue Michel Servet 1, 1211 Geneva 4, Switzerland; School of Pharmaceutical Sciences, University of Geneva, CMU - Rue Michel Servet 1, 1211 Geneva 4, Switzerland.
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