Multiple Heart-cutting Two-dimensional Liquid Research Articles

Multiple Heart-Cutting Two-Dimensional Liquid Chromatography: Recent Developments and Applications

Background: Over the last few decades, there has been a growing interest in Two- Dimensional Liquid Chromatography (2D-LC). This advanced technology has become a relevant solution for solving all the analytical challenges encountered in the pharmaceutical industry. The primary purpose of this review is to give a brief account of the developing techniques notable in 2D-LC. Methods: Review of recent literature on advanced separation techniques for complex mixtures revealed that 2D-LC is the most widely used technique in the pharmaceutical laboratory for the separation of complex samples. Among the various techniques used in 2D-LC, comprehensive 2D-LC and heart-cutting 2D-LC are highly used techniques. To enhance the resolution, further development has been made to heart-cutting 2D-LC called multiple heart-cutting 2D-LC, which has recently become a very popular technique in the pharmaceutical industry. Therefore research articles mentioning the use of multiple heart-cutting 2D-LC for separation of complex mixtures were reviewed. Results: The most crucial benefit of multiple heart-cutting 2D-LC is its reduced effort in method development and also the storage of multiple sample sections for further analysis. The multiple heartcutting 2D-LC is suited, preferably for method development and impurity analysis of pharmaceutical substances, fine chemicals and offers better peak separation, which is otherwise not possible by comprehensive 2D-LC. Conclusion: The advantage of two-dimensional liquid chromatography over one-dimensional liquid chromatography is its high resolving power. Further improvement in resolution was achieved by using the advanced multiple heart-cutting 2D-LC which appears to have an imperative role in pharmaceutical and food analysis.

Study of the impurity profile and polymerized impurity in mezlocillin sodium by multiple heart-cutting two-dimensional liquid chromatography coupled with ion trap time-of-flight mass spectrometry.

Eleven impurities and one polymerized impurity in mezlocillin were identified and their formation mechanisms were investigated in this study. The sources and reasons for the formation of impurities were revealed, which may guide industry to improve the manufacturing process and storage conditions and reduce the content of impurities in products. The results from this study also provided a scientific basis for the improvement of official monographs in pharmacopoeias. The impurity profiles and polymerized impurity in mezlocillin were studied by multiple heart-cutting two-dimensional liquid chromatography coupled with ion trap time-of-flight mass spectrometry (2D-LC/IT-TOF MS) in both positive and negative modes of electrospray ionization. Target eluents from the first dimensional chromatography with a non-volatile mobile phase were trapped and sent to the second dimensional chromatography with a volatile mobile phase by a switching valve. The structures of the impurities in the mezlocillin drug substance were deduced based on the high-resolution MSn data. In the environment of water, oxygen, high temperature, acid and base, a series of degradation products could be easily produced from mezlocillin. Mezlocillin was hydrolyzed into impurities I, IV, V and X, and was degraded into impurity III by methanolysis. Mezlocillin was oxidized into sulfoxide by producing impurity XI. Furthermore, impurities VI, VII, VII and IX were all isomers of mezlocillin. The proposed formation pathways of these products were demonstrated in this study. Eleven degradation impurities and one polymerized impurity in mezlocillin were separated and characterized. Based on characterization of impurities, this study discovered the mechanism of impurity production and provided guidance for manufacturers to improve the process and storage conditions and reduce levels of impurities.

Separation and Characterization of New Components and Impurities in Leucomycin by Multiple Heart-Cutting Two-Dimensional Liquid Chromatography Combined with Ion Trap/Time-of-Flight Mass Spectrometry

In this study, nine new components and six impurities in leucomycin were discovered. A method was developed for the separation and characterization of new components and impurities in leucomycin by multiple heart-cutting two-dimensional liquid chromatography combined with ion trap/time-of-flight mass spectrometry in both positive and negative electrospray ionization modes. With this method, a non-volatile buffer solution was used as mobile phase in the first-dimensional system for good separation. Eluent of each peak from the first-dimensional system was trapped by a switching valve and sent to the liquid chromatography-mass spectrometry system using a volatile mobile phase. The complete fragmentation patterns of the new components and degradation impurities were deduced based on MSn data. The structures of nine new components in leucomycin were deduced as unsaturated ketone in the 16-membered ring of leucomycin. The structures of six impurities were characterized for the first time, four of which were acid degradation products, and the other two were process impurities. The correlation between impurities and the purification process of leucomycin was also studied. The degradation impurities were produced during purification of leucomycin fermentation broth, which requires a low-pH environment. Based on the characterization of impurities, this study not only revealed the mechanism of impurity production, thus providing guidance to pharmaceutical companies for manufacturing process improvement and impurity reduction, but also provided a scientific basis for further improvement of official monographs in pharmacopoeias.

Chiral separation and chemical profile of Dengzhan Shengmai by integrating comprehensive with multiple heart-cutting two-dimensional liquid chromatography coupled with quadrupole time-of-flight mass spectrometry

Chemical profile for Chinese medicine formulas composed of several herbs is always a challenge due to a big array of small molecules with high chemical diversity so much as isomers. The present paper develops a feasible strategy to characterize and identify complex chemical constituents of a four-herb traditional Chinese medicine formula, Denzhan Shenmai (DZSM) by integrating comprehensive two-dimensional liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (LC×LC-qTOF-MS) with multiple heart-cutting two-dimensional liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (MHC-qTOF-MS). DZSM was separated by C8×C18 HPLC column system for comprehensive two-dimensional liquid chromatography system and 283 compounds most of which belonged to phenolic acid, flavonoid, saponin and lignan families were characterized and identified within 75min. Some isomers and compounds at low level were analyzed on C8×Chiral HPLC column system for multiple heart-cutting two-dimensional liquid chromatography system with 1D and 2D optimized gradient elution program. These 1D cutting fractions were successively separated on 2D chiral chromatographic column under extended the 2D gradient elution time from 30s to 5.0min. 12 pairs of isomer compounds were separated with good resolution. The combination of LC×LC and MHC system provides a powerful technique for global chemical profiling of DZSM and provided feasible strategy for other complex systems.

Multiple heart-cutting two dimensional liquid chromatography mass spectrometry: Towards real time determination of related impurities of bio-pharmaceuticals in salt based separation methods

Many of the chromatographic methods used in industry to determine related impurities in bio pharmaceuticals employ salt containing mobile phases. “Salty” mobile phases often provide superior chromatographic performance but are not compatible with mass spectrometry (MS) detection. Peak tracking necessary for method development is therefore often based on peak areas and the chemist’s experience/intuition. In addition, MS characterization of impurities usually is done by offline fraction collection, which apart from being time consuming often suffers from poor recovery or the degradation of impurities collected. The recent development of multiple heart-cutting (MHC) two-dimensional liquid chromatography (2D-LC) provides a way to address these problems. This study shows how MHC 2D-LC–MS can be used to obtain almost real time MS data for bovine insulin related impurities present at low level (<<0.03%). High quality MS spectra were obtained even for a first dimension using a mobile phase containing high concentrations of sodium, sulphate and phosphate. Thereby MHC 2D-LC–MS offers a possibility to eliminate the guesswork currently associated with peak tracking during method development. Furthermore, in contrast to current characterization methods involving fraction collection, solvent reduction/exchange etc., MS determination is done directly, which markedly shortens the workflow (from days to hours) and reduces the risk for poor recovery and degradation.

A chemical profiling solution for Chinese medicine formulas using comprehensive and loop-based multiple heart-cutting two-dimensional liquid chromatography coupled with quadrupole time-of-flight mass spectrometry

Chinese medicine formulas represent an excellent illustration for “complex matrix”. The complexity lies in a big array of small molecules with high chemical diversity. The present paper describes a novel chemical profiling solution for complex matrix by combining comprehensive and multiple heart-cutting two-dimensional liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (2DLC/qTOF–MS). This solution includes method optimization, combinational separation, and structural characterization. It was exemplified by fully profiling the chemical constituents of a four-herb traditional Chinese medicine formula, Gegen-Qinlian Decoction (GQD). GQD was separated by a RP×RP (C18×Phenyl-Hexyl) 2DLC system, and eluted with acidic×alkaline mobile phases with an optimized shift gradient elution program. In the comprehensive 2DLC mode, 280 peaks were detected, and 125 compounds were characterized within 42minutes. The multiple heart-cutting (MHC) mode extended the 2D modulation time to 3.0min to effectively separate the minor compounds. The 1D eluate within 4.4min was loaded into eleven 40-μL loops. These fractions were successively separated by 2D to resolve 13 additional compounds. The combination of comprehensive and MHC 2DLC/qTOF–MS provides a powerful technique for global chemical profiling of Chinese medicine formulas and other complex systems.

Loop-based multiple heart-cutting two-dimensional liquid chromatography for target analysis in complex matrices.

Loop-based multiple heart-cutting (MHC) two-dimensional liquid chromatography (2D-LC) is presented as a solution to quantify target components in complex matrices, such as additives in polymers, at very high chromatographic resolution. The determination of hexabromocyclododecane (HBCD) in polystyrene (PS) is described. One dimensional ((1)D) LC analysis with UV detection did not allow quantitation of the main isomers of HBCD due to peak overlap with polymer components. MHC 2D-LC analysis provided the separation power, accuracy, and repeatability needed for quantitative analysis of the additives of interest. Heart-cuts from peaks of the (1)D-chromatogram or entire regions of interest are sampled into loops, where they remain parked until their sequential reinjection onto the second dimension ((2)D) column. A column set consisting of phenyl ((1)D) and C18 ((2)D) stationary phases gave baseline separation in (2)D between HBCD and PS background. Linearity for spiked polymer samples was achieved over a range of 0.02-1.00 wt % HBCD relative to the amount of polymer. The limit of quantitation was estimated at 0.01 wt % HBCD in PS. A peak area RSD of 0.7% obtained for ten replicates of a real sample demonstrated excellent repeatability of the analysis. MHC 2D-LC is an elegant solution for quantitative analyses of difficult-to-separate samples when conventional (1)D separation fails.