Chiral stationary phases based on chitosan bis(methylphenylcarbamate)-(isobutyrylamide) for high-performance liquid chromatography

Abstract

a b s t r a c tA series of chitosan bis(methylphenylcarbamate)-(isobutyrylamide) derivatives were synthesized by carbamylating chitosan isobutyrylamide with different methylphenyl isocyanates. Then the prepared chitosan derivatives were coated onto 3-aminopropyl silica particles, resulting in a series of new chiral stationary phases (CSPs) for high-performance liquid chromatography. It was observed that the chiral recognition abilities of these coated-type CSPs depended very much on the substituents on the phenyl moieties of the chitosan derivatives, the eluent composition, as well as the structure of racemates. As a typical example, the eluent tolerance of the prepared CSP with the best enantioseparation ability was investigated in detail, and the results revealed that the CSP exhibited extraordinary solvent tolerance and could still work without significant loss in enantioseparation capability after being flushed with chloroform (100%), ethyl acetate (100%) and even THF/n-hexane (70/30, v/v), while the traditional coated-type CSPs based on the cellulose and amylose derivatives, such as cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC) and amylose tris(3,5-dimethylphenylcarbamate) (ADMPC), might be dissolved or highly swollen in these eluents. Therefore, the application of the resultant CSPs could address the problem of the dissolution and high swelling of traditional coated-type CSPs in some unusual eluents, broadening the possibility of eluent choice. In addition, a comparison of the prepared CSPs with the well known CDMPC-and ADMPC-based CSPs concerning the chiral recognition ability was also made. Separation performances achieved on the as-prepared CSPs in different eluents were found to be even superior to CDMPC-and ADMPC-based CSPs for the tested chiral compounds. In summary, we could safely draw the conclusion that the CSPs derived from chitosan isobutyrylamide derivatives were capable of excellent chiral recognition ability, and meanwhile possessed satisfactory eluent tolerance in a wider range of solvents.

HPLC with cellulose Tris (3,5‐DimethylPhenylcarbamate) chiral stationary phase: Influence of coating times and coating amount on chiral discrimination

“…The solution was added to the silica gel (2 g), and the wetted silica gel was dried under vacuum after it was dried at ambient temperature. 20 3 | RESULTS AND DISCUSSION According to the above coating method, a series of CSP-i-j samples were prepared when the amount of CDMPC and coating times were different.…”

“…Retention factor (k′), separation factor (α), resolution (Rs), and column efficiency (N) were calculated in the same way as previous literature. 20 3 | RESULTS AND DISCUSSION 3.1 | Characterizations of prepared CSP As described in Section 2, the wide-pore silica microspheres were prepared by calcinating silica after NaCl impregnation. Figure 2A-C showed the pore size distribution, particle size distribution, and SEM images of silica gel, respectively.…”

Chiral Stationary Phases for Liquid Chromatography Based on Chitin- and Chitosan-Derived Marine Polysaccharides

“…The best chromatographic result was achieved for flavanone with α and Rs values of 4.70 and 4.33, respectively, using a mixture of hexane/2-propanol 80:20 as mobile phase [65]. In recent studies (2016), Tang et al, prepared several bis-phenylcarbamate derivatives in which the amine moiety of chitosan was modified by an isobutyrylamide moiety (46)(47)(48)(49)(50)(51)(52)(53)(54)(55)(56)(57) [66,67]. The synthesized chitosan derivatives were coated on aminopropyl silica resulting in a series of new CSPs for LC.…”

“…Considering their poor solubility, they were able to withstand operations with other mobile phases than the typical hexane/2-propanol ( Table 5). They demonstrated high solvent tolerance and could still work after being flushed with chloroform (100%), ethyl acetate (100%) or In recent studies (2016), Tang et al, prepared several bis-phenylcarbamate derivatives in which the amine moiety of chitosan was modified by an isobutyrylamide moiety (46-57) [66,67]. The synthesized chitosan derivatives were coated on aminopropyl silica resulting in a series of new CSPs for LC.…”

Preparation and evaluation of a chiral HPLC stationary phase based on cone calix[4]arene functionalized at the upper rim with l‐alanine units

“…Development of new chiral stationary phases (CSPs) for HPLC with high chiral recognition for the separation of different chiral molecules is important in many fields including natural product research, stereospecific organic synthesis, pharmaceutical industry, food science and environmental studies. Recently, some new CSPs based on polysaccharides have been synthesized and used in HPLC (Feng, Chen, & Bai, ; Tang, Bin, Chen, Bai, & Huang, ; Zhang, Shen, Zuo, & Okamoto, ).…”