On the method development of immobilized polysaccharide chiral stationary phases in supercritical fluid chromatography using an extended range of modifiers

Investigation into the performance and stability of immobilized and coated polysaccharide columns in supercritical fluid chromatography

In this study, the performance of the widely used "golden four" coated chiral stationary phases (Chiralpak AD-3, Chiralcel OD-3, Chiralpak AS-3, and Chiralcel OJ-3) was compared with their corresponding immobilized versions (Chiralpak IA-3, Chiralpak IB-3, Chiralpak IB N-3, Chiralpak IH-3, and Chiralpak IJ-3) under supercritical fluid chromatography (SFC) conditions with a set of 30 racemic compounds. Using the traditional modifiers, methanol and isopropanol, the immobilized columns (Chiralpak IB N-3 and Chiralpak IH-3) showed an improved general ability to successfully resolve the enantiomers of the target analytes relative to their coated versions (Chiralcel OD-3 and Chiralpak AS-3), while the coated columns (Chiralpak AD-3, Chiralcel OD-3, and Chiralcel OJ-3) performed better than their immobilized versions (Chiralpak IA-3, Chiralpak IB-3, and Chiralpak IJ-3). An investigation of the non-traditional modifiers, dichloromethane, ethyl acetate, and tetrahydrofuran with immobilized columns, revealed a generally decreased ability to successfully resolve the enantiomers of the target analytes, relative to the use of the traditional modifiers, methanol and isopropanol. The stability of the coated columns (Chiralpak AD-H and Chiralcel OD-H) was evaluated by injecting "forbidden" solvents, including dichloromethane, dimethyl sulfoxide, and tetrahydrofuran. After 200 injections of these solvents on coated columns, the retention factors and resolutions slightly decreased, and a significant increase in column backpressure was observed, indicating some degree of stationary phase degradation.

Chiral Separation of Cannabichromene, Cannabicyclol, and Their Acidic Analogs on Polysaccharide Chiral Stationary Phases

Until recently, chirality has not been a major focus in the study of cannabinoids, as most cannabinoids of interest, such as cannabidiol and tetrahydrocannabinol, exist as a single isomer from natural sources. However, this is changing as more cannabinoids are identified, and compounds such as cannabichromene and cannabicyclol are emerging as potential investigatory candidates for varying indications. Because these molecules are chiral, the separation and study of the individual enantiomers' biological and physiological effects should therefore be of interest. The purpose of this study was to identify analytical separation conditions and then adapt those conditions to preparative separation. This was accomplished with a column-screening approach on Daicel's immobilized polysaccharide chiral stationary phases using non-traditional mobile phases, which included dichloromethane, ethyl acetate, and methyl tert-butyl ether under high-performance liquid chromatography conditions. CHIRALPAK^® IK was found to separate all four compounds well with mobile phases containing hexane-dichloromethane (with or without an acidic additive). From these methods, the separation productivities were calculated to better visualize the separation scalability, which shows that the kilogram-scale separations of each are feasible.

The separation of several organophosphate pesticides on immobilized polysaccharide chiral stationary phases

While not initially a focus or priority, in recent decades, an emphasis has been placed on the activity of individual enantiomers of widely used pesticides. Of particular note are organophosphorus-based pesticides like fenamiphos and profenofos, as examples. This work explores the enantioselective high-performance liquid chromatography (HPLC) separations of seven such organophosphorus pesticides (OP's) on the library of immobilized polysaccharide-based chiral stationary phases (CSPs) with normal phase hexane/alcohol mixtures. Further exploration of the effect of mobile phase strength and temperature on several of the separations was performed using simple factorial design. Equivalent retention of the first eluting enantiomer of several combinations of temperature and mobile phase was compared for peak shape, selectivity, and resolution. Similarly, equivalent selectivity of several combinations of temperature and mobile phase was compared for peak shape, retention of the first eluting enantiomer, and resolution. The results of this study make available several new chiral separations of the OPs included in the work that were not previously documented, including separations on the three most recently commercialized phases, Chiralpak IH, IJ, and IK. Additionally, sufficient understanding was obtained to be able to predict the trade-off of resolution, analysis time, peak sharpness (and thus improve limit-of-detection [LOD]/limit-of-quantification [LOQ]), robustness, and convenience of conditions for further application optimization.

Polysaccharides as separation media for the separation of proteins, peptides and stereoisomers of amino acids

Reliable separation of peptides, amino acids and proteins as accurate as possible with the maximum conformation and biological activity is crucial and essential for drug discovery. Polysaccharide, as one of the most abundant natural biopolymers with optical activity on earth, is easy to be functionalized due to lots of hydroxyl groups on glucose units. Over the last few decades, polysaccharide derivatives are gradually employed as effective separation media. The highly-ordered helical structure contributes to complex, diverse molecular recognition ability, allowing polysaccharide derivatives to selectively interact with different analytes. This article reviews the development, application and prospects of polysaccharides as separation media in the separation of proteins, peptides and amino acids in recent years. The chiral molecules mechanism, advantages, limitations, development status and challenges faced by polysaccharides as separation media in molecular recognition are summarized. Meanwhile, the direction of its continued development and future prospects are also discussed.

Efficient preparative separation of 6-(4-aminophenyl)-5-methyl-4, 5-dihydro-3(2H)-pyridazinone enantiomers on polysaccharide-based stationary phases in polar organic solvent chromatography and supercritical fluid chromatography

6-(4-Aminophenyl)-5-methyl-4,5-dihydro-3(2H)-pyridazinone is a key synthetic intermediate for cardiotonic agent levosimendan. Very few studies address the use of chiral stationary phases in chromatography for the enantioseparation of this intermediate. This study presents two efficient preparative methods for the isolation of (R)(-)-6-(4-aminophenyl)-5-methyl-4,5-dihydro-3(2H)-pyridazinone in polar organic solvent chromatography and supercritical fluid chromatography using polysaccharide-based chiral stationary phases and volatile organic mobile phases without additives in isocratic mode. Under optimum conditions, Chiralcel OJ column showed the best performance (α = 1.71, Rs = 5.47) in polar organic solvent chromatography, while Chiralpak AS column exhibited remarkable separations (α = 1.81 and Rs = 6.51) in supercritical fluid chromatography with an opposite enantiomer elution order. Considering the sample solubility, runtime and solvent cost, the preparations were carried out on Chiralcel OJ column and Chiralpak AS column (250 × 20 mm i.d.; 10 µm) in polar organic mode and supercritical fluid chromatography mode with methanol and CO₂ /methanol as mobile phases, respectively. By utilizing the advantages of chromatographic techniques and polysaccharide-based chiral stationary phases, this work provides two methods for the fast and economic preparation of (R)(-)-6-(4-aminophenyl)-5-methyl-4,5-dihydro-3(2H)-pyridazinone, which are suitable for the pharmaceutical industry.

Performance comparison of chlorinated chiral stationary phases in supercritical fluid chromatography for separation of selected pyrrolidone derivatives

The effects of two chlorinated chiral stationary phases, namely, Lux Cellulose-2 and Lux i-Cellulose-5, flow-rate, percentage of co-solvent and chemical structures of the compounds on retention and resolution were studied within this article. In this work a backpressure of 150 bar, a temperature of 40 °C and 10% of methanol as co-solvent were chosen as operating conditions. The optimum flow-rate was 2 mL/min. The percentage of co-solvent was studied between 7.5% and 15%. We have observed that 15% of methanol gave the best results for most of the compounds. For all the derivatives, the Lux Cellulose-2 provided better resolutions going from 1.50 to 3.59 compared with Lux i-Cellulose-5.

Enantiomer separation of propranolol and tryptophan using bovine serum albumin functionalized silica nanoparticles as adsorbents

The immobilization of popular chiral selectors on the surface of nanomaterials to prepare new chiral adsorbents for preparative chiral separation is a research hotspot in separation science nowadays.