Semipreparative enantiomer separation of propranolol hydrochloride by high-performance liquid chromatography using cellulose tris(3,5-Dimethylphenylcarbamate) chiral stationary phase.

In this paper, we describe the direct semipreparative resolution of racemic (rac)-propranolol hydrochloride by high-performance liquid chromatography using cellulose tris(3,5-dimethylphenylcarbamate) as chiral stationary phase and mobile phase systems containing petroleum ether and 2-propanol with the use of basic additives. At analytical scale, the retention factor of both enantiomers is less than 5 with the separation factor 1.95 and the resolution 2.4. Then, the analytical method is scaled up to semipreparative loading to obtain small amounts of both propranolol hydrochloride enantiomers. Petroleum ether, rather than n-hexane, is used to effectively reduce the production cost of (R)- and (S)-propranolol. To increase the throughput, overlapping injections are used, allowing an injection to be made every 6.5 min instead of every 12 min. At semipreparative scale, approximately 19 mg/h enantiomers are isolated. The first fraction [(R)-(+)-propranolol hydrochloride] is isolated with a purity of > 99.6% (e.e.) and > 97.0% yield, and the second [(S)-(-)-propranolol hydrochloride] is isolated with a purity of > 99.3% (e.e.) and > 95.0% yield. In addition, optical rotations of both propranolol hydrochloride enantiomers isolated are investigated.

Capillary zone electrophoresis for separation and analysis of four diarylheptanoids and an alpha-tetralone derivative in the green walnut husks (Juglans regia L.).

A fast capillary zone electrophoresis (CZE) method for the simultaneous determination of four cyclic diarylheptanoids (rhoiptelol, RH; juglanin A, JA; juglanin B, JB; juglanin C, JC) and an alpha-tetralone derivative (sclerone, SC) in the extract of the green walnut husks (Juglans regia L.) was developed. The optimized buffer was composed of 25 mM sodium tetraborate at pH 10.3. The applied voltage was 20 kV and the capillary temperature was kept constant at 20 degrees C. The detection wavelength was set at 220 nm using a photodiode array detection. The effects of several CE parameters, including pH value, buffer concentration, applied voltage and separation temperature on the separation were investigated systematically. Regression equations showed good linear relationships (correlation coefficients: 0.9996-0.9999) between the peak area of each compound (RH, JA, JB, JC and SC) and its concentration accordingly. The relative standard deviations (R.S.D.) of the migration time and peak area were less than 0.57 and 3.44% (intra-day), and 0.97 and 3.71% (inter-day), respectively. The contents of the five active compounds in the green walnut husks (J. regia L.) from different origins were determined with satisfactory repeatability and recovery.

Fingerprint quality control of Angelica sinensis (Oliv.) Diels by high-performance liquid chromatography coupled with discriminant analysis.

High-performance liquid chromatography (HPLC) was employed in the fingerprint analysis of Angelica sinensis (Oliv.) Diels. A chromatographic profile of A. sinensis (Oliv.) Diels from the Dingxi District of Gansu province, China, was established as the characteristic fingerprint. The feasibility and advantages of employing chromatographic fingerprint combined with discriminant analysis were investigated and demonstrated for the evaluation of A. sinensis (Oliv.) Diels for the first time. Our results showed that the chromatographic fingerprint combining with discriminant analysis can efficiently distinguish A. sinensis (Oliv.) Diels from various areas.

[Study on the extraction process for salidroside and p-tyrosol in Rhodiola crenulata].

OBJECTIVE: To investigate the optimum ethanol extraction process conditions for salidroside and p-tyrosol from Rhodiola crenulata. METHODS: The extraction rate of ethanol extract and content of salidroside and p-tyrosol were chosen as the assessment index by using the orthogonal design. The ethanol content (%), solvent quantum (fold) and extracting time (hour) were reviewed. RESULTS: The optimum ethanol extraction process conditions were as follows: adding 6 fold of 80% ethanol, extracting for 2h and 2 times. CONCLUSION: The optimum extraction process can give a reference to the research of new medicine and production of industry.

[Determination of four alkaloids in Berberis plants by HPLC].

OBJECTIVE: In order to assess Berberis, a simple and effective high-performance liquid chromatographic (HPLC) method was established. METHOD: By applying HPLC with gradiation elution, this method was developed for determination of four kinds of alkaloids including berbamine, Jatrorrhizine, berberine and palmatine in methanolic extracts from root bark, root, stem bark and stem of Berberis. RESULT: The alkaloids berbamine, jatrorrhizine, berberine and palmatine shown good linear correlations in the range of 0.028-4.74 microg (r = 0.9998); 0.012-2.0 microg (r = 0.9996); 0.026-0.52 microg (r = 0.9999); 0.015-2.56 microg (r = 0.9998), respectively. The correlation coefficients of the calibration curve for the analytes exceeded 0.9998. CONCLUSION: The optimized HPLC method was applied to analyze various samples, and the results shown that the content of alkaloids were obvious difference in Berberis from different area, different species and different parts.

[Effect of the bonding amounts of chiral ligand exchange chromatographic stationary phases on the enantioseparation of amino acids].

L-proline chiral stationary phases with various bonding amounts for ligand exchange chromatography were prepared by treating silica gel with 3-glycidoxypropyltrimethoxysilane and bonding L-proline. The bonding amounts of L-proline chiral stationary phase were controlled effectively and characterized by IR and elemental analysis. Some DL-amino acids were separated and the influences of the bonding amounts on the efficiency of resolution of DL-amino acids by ligand exchange chromatography were briefly discussed and explained by the mechanism of the separation.

[Influence of mobile phase composition on chiral separation of organic selenium racemates].

The chiral separation of some chiral compounds with similar structure on the cellulose tris (3,5-dimethylphenylcarbamate) chiral stationary phase prepared by us was obtained. Ternary mobile phases influencing chiral recognition were investigated. A mode of interaction between the structural character of samples and chiral stationary phase is discussed. The results indicated that the retention and chiral separation of the analytes had a bigger change with minute addition of alcohols or acetonitrile as modifier in n-hexane/2-propanol (80/20, volume ratio) binary mobile phase.

[Preparation of polymer modified stationary phases through surface radical chain transfer reaction].

It is demonstrated that radical chain transfer to thiol-terminated self-assembled monolayer and surface-initiated polymerization could be used for in-situ grafting ultra-thin polymer film on silica. The widely used silane coupling agent mercaptopropyltrimethoxysilane (MPS) was used to prepare the thiol-terminated silica, and in the presence of which, chain-transfer reaction and polymerization of methyl methacrylate (MMA) was carried out using azo di-isobutylnitrile (AIBN) as the initiator. Both thiol-terminated silica and polymer film modified silica were characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, thermogravimetric analysis (TGA) and elemental analysis. The results showed that the grafting amount of polymer on silica was higher than the traditional methods, which can effectively relieve the non-specific adsorption of solute with uncovered hydroxyl groups on the surfaces of silica in subsequent chromatographic application. The obtained polymethylmethacrylate (PMMA) modified silica exhibited excellent separation capacity on the separation of the polar compounds and polycyclic aromatic hydrocarbons. This kind of surface initiated polymerization prospects for the preparation of polymer modified stationary phases.