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Boelrijk J, Molenaar SRA, Bos TS, Dahlseid TA, Ensing B, Stoll DR, Forré P, Pirok BWJ. Enhancing LC×LC separations through multi-task Bayesian optimization. J Chromatogr A 2024; 1726:464941. [PMID: 38749274 DOI: 10.1016/j.chroma.2024.464941] [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: 02/16/2024] [Revised: 04/17/2024] [Accepted: 04/22/2024] [Indexed: 05/23/2024]
Abstract
Method development in comprehensive two-dimensional liquid chromatography (LC×LC) is a challenging process. The interdependencies between the two dimensions and the possibility of incorporating complex gradient profiles, such as multi-segmented gradients or shifting gradients, make trial-and-error method development time-consuming and highly dependent on user experience. Retention modeling and Bayesian optimization (BO) have been proposed as solutions to mitigate these issues. However, both approaches have their strengths and weaknesses. On the one hand, retention modeling, which approximates true retention behavior, depends on effective peak tracking and accurate retention time and width predictions, which are increasingly challenging for complex samples and advanced gradient assemblies. On the other hand, Bayesian optimization may require many experiments when dealing with many adjustable parameters, as in LC×LC. Therefore, in this work, we investigate the use of multi-task Bayesian optimization (MTBO), a method that can combine information from both retention modeling and experimental measurements. The algorithm was first tested and compared with BO using a synthetic retention modeling test case, where it was shown that MTBO finds better optima with fewer method-development iterations than conventional BO. Next, the algorithm was tested on the optimization of a method for a pesticide sample and we found that the algorithm was able to improve upon the initial scanning experiments. Multi-task Bayesian optimization is a promising technique in situations where modeling retention is challenging, and the high number of adjustable parameters and/or limited optimization budget makes traditional Bayesian optimization impractical.
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Affiliation(s)
- Jim Boelrijk
- AI4Science Lab, Informatics Institute, University of Amsterdam, Amsterdam, Science Park 904, 1098 XH, The Netherlands; AMLab, Informatics Institute, University of Amsterdam, Amsterdam, Science Park 904, 1098 XH, The Netherlands.
| | - Stef R A Molenaar
- Division of Bioanalytical Chemistry, Amsterdam Institute of Molecular and Life Sciences, De Boelelaan 1085, Amsterdam, 1081 HV, The Netherlands; Analytical Chemistry Group, Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam, Science Park 904, 1098 XH, The Netherlands
| | - Tijmen S Bos
- Division of Bioanalytical Chemistry, Amsterdam Institute of Molecular and Life Sciences, De Boelelaan 1085, Amsterdam, 1081 HV, The Netherlands; Analytical Chemistry Group, Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam, Science Park 904, 1098 XH, The Netherlands
| | - Tina A Dahlseid
- Department of Chemistry, Gustavus Adolphus College, Saint Peter, MN 56082, United States
| | - Bernd Ensing
- AI4Science Lab, Informatics Institute, University of Amsterdam, Amsterdam, Science Park 904, 1098 XH, The Netherlands; Computational Chemistry Group, Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam, Science Park 904, 1098 XH, The Netherlands
| | - Dwight R Stoll
- Department of Chemistry, Gustavus Adolphus College, Saint Peter, MN 56082, United States
| | - Patrick Forré
- AI4Science Lab, Informatics Institute, University of Amsterdam, Amsterdam, Science Park 904, 1098 XH, The Netherlands; AMLab, Informatics Institute, University of Amsterdam, Amsterdam, Science Park 904, 1098 XH, The Netherlands
| | - Bob W J Pirok
- AI4Science Lab, Informatics Institute, University of Amsterdam, Amsterdam, Science Park 904, 1098 XH, The Netherlands; Analytical Chemistry Group, Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam, Science Park 904, 1098 XH, The Netherlands.
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Boelrijk J, Ensing B, Forré P, Pirok BWJ. Closed-loop automatic gradient design for liquid chromatography using Bayesian optimization. Anal Chim Acta 2023; 1242:340789. [PMID: 36657888 DOI: 10.1016/j.aca.2023.340789] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 12/13/2022] [Accepted: 01/02/2023] [Indexed: 01/07/2023]
Abstract
Contemporary complex samples require sophisticated methods for full analysis. This work describes the development of a Bayesian optimization algorithm for automated and unsupervised development of gradient programs. The algorithm was tailored to LC using a Gaussian process model with a novel covariance kernel. To facilitate unsupervised learning, the algorithm was designed to interface directly with the chromatographic system. Single-objective and multi-objective Bayesian optimization strategies were investigated for the separation of two complex (n>18, and n>80) dye mixtures. Both approaches found satisfactory optima in under 35 measurements. The multi-objective strategy was found to be powerful and flexible in terms of exploring the Pareto front. The performance difference between the single-objective and multi-objective strategy was further investigated using a retention modeling example. One additional advantage of the multi-objective approach was that it allows for a trade-off to be made between multiple objectives without prior knowledge. In general, the Bayesian optimization strategy was found to be particularly suitable, but not limited to, cases where retention modelling is not possible, although its scalability might be limited in terms of the number of parameters that can be simultaneously optimized.
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Affiliation(s)
- Jim Boelrijk
- AI4Science Lab, Informatics Institute, University of Amsterdam, Amsterdam, Science Park 904, 1098 XH, the Netherlands; AMLab, Informatics Institute, University of Amsterdam, Amsterdam, Science Park 904, 1098 XH, the Netherlands.
| | - Bernd Ensing
- AI4Science Lab, Informatics Institute, University of Amsterdam, Amsterdam, Science Park 904, 1098 XH, the Netherlands; Computational Chemistry Group, Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam, Science Park 904, 1098 XH, the Netherlands
| | - Patrick Forré
- AI4Science Lab, Informatics Institute, University of Amsterdam, Amsterdam, Science Park 904, 1098 XH, the Netherlands; AMLab, Informatics Institute, University of Amsterdam, Amsterdam, Science Park 904, 1098 XH, the Netherlands
| | - Bob W J Pirok
- AI4Science Lab, Informatics Institute, University of Amsterdam, Amsterdam, Science Park 904, 1098 XH, the Netherlands; Analytical Chemistry Group, Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam, Science Park 904, 1098 XH, the Netherlands.
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A comparison of 2 micron inner diameter open tubular column liquid chromatography with pressure-driven isocratic, slip-flow, and electrochromatographic modes of operation: a theoretical study. J Chromatogr A 2020; 1638:461818. [PMID: 33516049 DOI: 10.1016/j.chroma.2020.461818] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 12/12/2020] [Accepted: 12/13/2020] [Indexed: 11/22/2022]
Abstract
Modifications to the flow profile used in open tube capillary liquid chromatography (OT-CLC) include using slip-flow walls and using electroosmosis as a fluid pump as practiced in electrochromatography. These modifications are implemented experimentally by changing the capillary surface and solvent conditions which results in the change of boundary conditions at the capillary wall. In this paper we employ a theory-based study and compare the zone broadening of simple solutes using parabolic flow from a liquid pump, slip-flow from a highly hydrophobic inner surface with water eluent, and electroosmosis for the conditions of pure water and dilute salt utilizing 2 µm inner diameter OT capillaries. In general, the two types of flow other than parabolic exhibit thin zones in the early part of the chromatogram, consistent with previous studies of slip-flow and electroosmotic flow used in electrochromatography. Electrochromatography is shown to yield higher efficiency and less zone broadening than parabolic and slip-flow conditions used in this study. Nonetheless, it is found that the zone standard deviations are shown to be similar for these flow profiles as is the number of plates for these different flow profiles under the conditions utilized here. It is revealed that these modifications do not warrant the effort to maintain the special solvent conditions when compared to gradient elution OT-CLC, which gives a nearly constant peak width throughout the chromatogram, is easiest to implement, and is the method of choice for complex analysis.
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Hao W, Li B, Deng Y, Chen Q, Liu L, Shen Q. Computer aided optimization of multilinear gradient elution in liquid chromatography. J Chromatogr A 2020; 1635:461754. [PMID: 33276285 DOI: 10.1016/j.chroma.2020.461754] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 11/19/2020] [Accepted: 11/23/2020] [Indexed: 01/16/2023]
Abstract
Analytical expressions for retention time and peak compression factor are deduced by assuming quadratic solvent strength model and multilinear gradient elution. Based on these expressions, a program for the optimization of multilinear gradient profile is written with Visual Basic for Applications in Excel using genetic algorithm. The program is applied to search for a gradient profile for the separation of twelve compounds that are degraded from lignin. It is shown that the predicted and experimental chromatograms are well consistent. A better separation of the compounds is achieved under an S-shaped multilinear gradient profile than that obtained under linear gradient profile.
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Affiliation(s)
- Weiqiang Hao
- Changzhou Vocational Institute of Engineering, School of Inspection and Testing Certification, Changzhou 213164, China; High-Tech Research Institute of Nanjing University, Changzhou 213164, China.
| | - Bo Li
- Department of Pharmaceutical Analysis, China Pharmaceutical University, Nanjing 210009, China
| | - Yuying Deng
- Changzhou Vocational Institute of Engineering, School of Inspection and Testing Certification, Changzhou 213164, China
| | - Qiang Chen
- High-Tech Research Institute of Nanjing University, Changzhou 213164, China
| | - Lijuan Liu
- Changzhou Vocational Institute of Engineering, School of Inspection and Testing Certification, Changzhou 213164, China
| | - Qiaoyin Shen
- Changzhou Vocational Institute of Engineering, School of Inspection and Testing Certification, Changzhou 213164, China
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