Preparation of chitosan‐graft‐(β‐cyclodextrin) based sol‐gel stationary phase for open‐tubular capillary electrochromatography

A novel open‐tubular CEC column coated with chitosan‐graft‐(β‐CD) (CDCS) was prepared using sol‐gel technique. In the sol‐gel approach, owing to the 3D network of sol‐gel and the strong chemical bond between the stationary phase and the surface of capillary columns, good chromatographic characteristics and unique selectivity in separating isomers were shown. The column efficiencies of 55 000～163 000 plates/m for the isomeric xanthopterin and phenoxy acid herbicides using the sol‐gel‐derived CDCS columns were achieved. Good stabilities were demonstrated that the RSD values for the retention time of thiourea and isoxanthopterin were 1.3 and 1.4% (run to run, n = 5), 1.6 and 2.0% (day to day, n = 3), 2.9 and 3.1% (column to column, n = 3), respectively. The sol‐gel‐coated CDCS columns have shown improved separations of isomeric xanthopterin in comparison with CDCS‐bonded capillary column.     

Separation of somatropin charge variants by multiple‐injection CZE with Polybrene/chondroitin sulfate A double‐coated capillaries

The performance of dynamic double‐coated fused‐silica capillaries with Polybrene and chondroitin sulfate A has been compared with uncoated fused‐silica capillaries for the determination of recombinant human growth factor (somatropin) charge variants. The separations were carried out under the same electrophoretic conditions as described in the European Pharmacopoeia, i.e. at pH 6.0 and 30°C. The coating significantly reduced the interactions between the proteins and the surface of the fused‐silica capillary. The first five separations performed in a new bare fused‐silica capillary were discarded because of very poor separation performance as a result of protein–surface interactions. There was an approximate twofold increase in the interday migration time precision (%RSD ≤ 6.5%) in the double‐coated capillaries. The method was successfully transferred to a multiple CZE mode where two samples were analyzed in a single electrophoretic run. The average purity of somatropin certified reference standard was 98.0% (%RSD ≤ 0.3%) determined by using uncoated and coated capillaries.     

Temperature‐programmed multicapillary gas chromatograph microcolumn for the analysis of odorous sulfur pollutants

We report the fabrication and performance of a silicon‐on‐glass micro gas chromatography eight‐capillary column based on microelectromechanical systems technology that is 50 cm long, 30 μm wide, and 300 μm deep. According to the theory of a gas chromatography column, an even gas flow among different capillaries play a vital role in the peak broadening. Thus, a flow splitter structure is designed by the finite element method through the comparison of the velocity distributions of the eight‐capillary columns with and without splitter as well as an open tubular column. The simulation results reveal that eight‐capillary column with flow splitters can receive more uniform flow velocity in different capillaries, hence decreases the peak broadening and in turn increases the separation efficiency. The separation experiment results show that the separation efficiency of about 22 000 plates/m is achieved with the chip column temperature programmed for analysis of odorous sulfur pollutants. This figure is nearly two times higher than that of the commercial capillary column coated the similar stationary phase. And the separation time of all the components in the microcolumn is less than 3.8 min, which is faster than the commercial capillary column.     

Preparation and evaluation of open‐tubular capillary column combining a metal–organic framework and a brush‐shaped polymer for liquid chromatography

In this work, an open‐tubular capillary liquid‐phase column was prepared by modifying chain polymer on the inner surface of capillary and chemical bonding of metal organic frameworks, NH₂‐UiO‐66, to the brushes of chain polymer (poly(glycidyl methacrylate)). Besides advantages of facial preparation and good permeability, the chain polymer effectively increases the modification amount of NH₂‐UiO‐66 nanoparticles to increase the phase ratio of open‐tubular capillary column and enhance the interactions with analytes. The results of scanning electron microscope energy‐dispersive X‐ray spectra indicated that NH₂‐UiO‐66 nanoparticles were successfully bonded to the chain polymer. Because of the hydrophobic interaction and hydrogen bonding interaction between the analytes and the ligand of NH₂‐UiO‐66, different analytes were well separated on the NH₂‐UiO‐66‐modified poly(glycidyl methacrylate) capillary (1.12 m × 25 μm id × 365 μm od) with the high absolute column efficiency reaching 121 477 plates, benefiting from an open‐tubular column and low mass transfer resistance provided by polymer brush and metal–organic framework crystal. The relative standard deviations of the retention time for run‐to‐run, day‐to‐day, and column‐to‐column (n = 3) runs are below 4.28%, exhibiting good repeatability. Finally, the column was successfully applied to separation of flavonoids in licorice.     

Triamine‐bonded stationary phase for open tubular capillary electrochromatography

A multi‐functional separation column modified with 3‐[2‐(2‐aminoethylamino)ethylamino] propyl‐trimethoxysilane was developed for open tubular capillary electrochromatography. This functional hydrophilic triamine‐bonded open tubular column could generate both anodic and cathodic EOF. When the pH of the running buffer was below 5.3 (30% 3‐[2‐(2‐aminoethylamino)ethylamino] propyl‐trimethoxysilane, v/v), the anodic EOF was exhibited, which greatly prevented the undesired adsorptions of basic proteins on the capillary inner wall. Favorable separation of four basic proteins (viz. trypsin, ribonuclease A, lysozyme and cytochrome c) was successfully achieved at pH 3.5 of 10 mmol/L phosphate buffer. The column efficiencies of proteins were in the range from 87 000 to 110 000 plates/m, and the RSD values for migration time of four proteins were less than 1.2% (run‐to‐run, n=5). The ionic analytes were also separated efficiently in the co‐electroosmotic mode. The average efficiencies ranged from 81 000 to 190 000 plates/m for seven aromatic acids and 186 000–245 000 plates/m for four nucleoside monophosphates, respectively, and good capillary column repeatability was gained with RSD of the migration time not more than 3.0%. The triamine‐bonded open tubular capillary column is favorable to be an alternative functional medium for the further analysis of basic proteins and anionic analytes.     

Photografted methacrylate‐based monolithic columns coated with cellulose tris(3,5‐dimethylphenylcarbamate) for chiral separation in CEC

A chiral capillary monolithic column for enantiomer separation in capillary electrochromatography was prepared by coating cellulose tris(3,5‐dimethylphenylcarbamate) on porous glycidyl methacrylate‐co‐ethylene dimethacrylate monolith in capillary format grafted with chains of [2(methacryloyloxy)ethyl] trimethylammonium chloride. The surface modification of the monolith by the photografting of [2(methacryloyloxy)ethyl] trimethylammonium chloride monomer as well as the coating conditions of cellulose tris(3,5‐dimethylphenylcarbamate) onto the grafted monolithic scaffold were optimized to obtain a stable and reproducible chiral stationary phase for capillary electrochromatography. The effect of organic modifier (acetonitrile) in aqueous mobile phase for the enantiomer separation by capillary electrochromatography was also investigated. Several pairs of enantiomers including acidic, neutral, and basic analytes were tested and most of them were partially or completely resolved under aqueous mobile phases. The prepared monolithic chiral stationary phases exhibited a good stability, repeatability, and column‐to‐column reproducibility, with relative standard deviations below 11% in the studied electrochromatographic parameters.     

Enantiomeric Separations of Acidic and Neutral Compounds by Capillary Electrochromatography with β‐Cyclodextrin‐Bonded Positively Charged Polyacrylamide Gels

The novel enantiomeric separation of acidic and neutral compounds by capillary electrochromatography with β‐cyclodextrin‐bonded positively charged polyacrylamide gels was examined. The columns used are capillaries filled with a positively charged polyacrylamide gel, a so‐called monolithic stationary phase, to which allyl carbamoylated β‐CD derivatives covalently bind. The capillary wall was activated first by bifunctional reagent to make the resulting gel bind covalently inside the fused‐silica tubing. Enantiomeric separations of sixteen acidic and two neutral compounds were achieved using the above‐mentioned columns and 200 mmol dm^–3 Tris–300 mmol dm^–3 boric acid buffer (pH 8.1) as a mobile phase. High efficiencies of up to 150 000 plates m^–1 were obtained for dansyl‐DL‐amino acids. The within‐run and between‐run reproducibilities of retention time and separation factor were examined for three dansyl‐DL‐amino acids and warfarin. The relative standard deviations of the within‐run and between‐run reproducibilities of retention time were less than 1.2 and 1.3% over the six injections, respectively. Those of the separation factor were less than 0.3 and 0.2%, respectively. The gel‐filled capillaries were stable for at least four months with intermittent use.     

Evaluation of poly([2‐(acryloyloxy)ethyl]trimethylammonium chloride) cationic polymer capillary coating for capillary electrophoresis and electrokinetic chromatography separations

Capillary electrophoresis and electrokinetic chromatography are typically carried out in unmodified fused‐silica capillaries under conditions that result in a strong negative zeta potential at the capillary wall and a robust cathodic electroosmotic flow. Modification of the capillary wall to reverse the zeta potential and mask silanol sites can improve separation performance by reducing or eliminating analyte adsorption, and is essential when conducting electrokinetic chromatography separations with cationic latex nanoparticle pseudo‐stationary phases. Semipermanent modification of the capillary walls by coating with cationic polymers has proven to be facile and effective. In this study, poly([2‐(acryloyloxy)ethyl]trimethylammonium chloride) polymers were synthesized by reversible addition‐fragmentation chain transfer polymerization and used as physically adsorbed semipermanent coatings for capillary electrophoresis and electrokinetic chromatography separations. An initial synthesis of poly([2‐(acryloyloxy)ethyl]trimethylammonium chloride) polymer coating produced strong and stable anodic electroosmotic flow of –5.7 to –5.4 × 10⁻⁴ cm²/V⋅s over the pH range of 4–7. Significant differences in the magnitude of the electroosmotic flow and effectiveness were observed between synthetic batches, however. For electrokinetic chromatography separations, the best performing batches of poly([2‐(acryloyloxy)ethyl]trimethylammonium chloride) polymer performed as well as the commercially available cationic polymer polyethyleneimine, whereas polydiallylammonium chloride and hexadimethrine bromide did not perform well.     

A covalent capillary coating of diazoresin and polyglycerol dendrimer for protein analysis using capillary electrophoresis

Overcoming proteins adsorption on the inner surface of capillary has attracted increasing attention recently. By using the unique photochemistry reaction of diazoresin (DR), a new covalent capillary coating was prepared on the fused‐silica capillary through layer‐by‐layer self‐assembly of DR with polyglycerol (PG) dendrimer. The separation performance of covalently DR/PG‐dendrimer coated capillary noticeably exceeded the bare capillary and the noncovalently linked DR/PG‐dendrimer capillary. A baseline separation of lysozyme, myoglobin, bovine serum albumin, and ribonuclease A was achieved using CE within 20 min. Besides, the covalently linked DR/PG‐dendrimer coating has the remarkable stability and reproducibility. Especially, compared with the traditional method which use highly toxic and moisture‐sensitive silane coupling agent, this method seems to be a simple and environmental friendly way to prepare the covalently coated capillaries for CE.     

Capillary electrophoresis using core‐based hyperbranched polyethyleneimine (CHPEI) static‐coated capillaries

With unique 3‐D architecture, the application of core‐based hyperbranched polyethyleneimine (CHPEI), as a capillary coating in capillary electrophoresis, is demonstrated by manipulation of the electroosmotic mobility (EOF). CHPEI coatings (CHPEI5, M_w ≈? 5000 and CHPEI25, M_w ≈? 25 000) were physically adsorbed onto the inner surface of bare fused‐silica capillary (BFS) via electrostatic interaction of the oppositely charged molecules by rinsing the capillaries with different CHPEI aqueous solutions. The EOF values of the coated capillaries were measured over the pH range of 4.0–9.0. At higher pH (pH >6) the coated capillary surface possesses excess negative charges, which causes the reversal of the EOF. The magnitudes of the EOF obtained from the coated capillaries were three‐fold lower than that of BFS capillary. Desirable reproducibility of the EOF with % RSD (n = 5) ? 2 was obtained. Effect of ionic strength, stability of the coating (% RSD = 0.3) and the dependence of the EOF on pH (% RSD = 0.5) were also investigated. The CHPEI‐coated capillaries were successfully utilized to separate phenolic compounds, B vitamins, as well as basic drugs and related compounds with reasonable analysis time (<20 min) and acceptable migration‐time repeatability (<0.7% RSD for intra‐capillary and <2% RSD for inter‐capillary).     

超支化聚酯化学键合涂层毛细管电泳柱的制备及碱性蛋白质的分离

用一步法和准一步法合成了以三羟甲基丙烷为核的两个系列的超支化聚酯,利用红外光谱、羟值测定等手段对其分子结构进行了表征。利用超支化聚合物低粘度的特点,采用化学键合的方法将其涂于石英毛细管电泳柱内壁,使其在毛细管内壁上形成稳定的超支化聚酯涂层。该涂层在pH 3.0~7.0范围内能够有效地抑制电渗流和碱性蛋白质在毛细管壁上的吸附。实验结果表明:该涂层柱在pH 5.0的磷酸缓冲溶液中,对碱性蛋白质的分离柱效可高达塔板数106/m。每次运行之间(n=6),天与天之间(n=3),以及柱与柱之间(N=3)的迁移时间的标准偏差(RSD%)在0.5%~1.5%之间,表明本方法制得的涂层柱具有良好的稳定性。     

Fast separation of enantiomers by capillary electrophoresis using a combination of two capillaries with different internal diameters

The combination of capillaries with different internal diameters was used to accelerate the separation of enantiomers in capillary electrophoresis. Separation of R ,S‐1,1′‐binaphthalene‐2,2′‐diyl hydrogen phosphate using isopropyl derivative of cyclofructan 6 was studied as a model system. The best separation conditions included 500 mM sodium borate pH 9.5 with 60 mM concentration of the chiral selector. Separation lasted approx. 1.5 min using the combination of 50 and 100 μm id capillaries of 9.7 cm and 22.9 cm, respectively. It allowed approx. 12‐fold acceleration in comparison to the traditional long‐end separation mainly due to the higher electroosmotic flow generated in the connected capillaries.     

Cationic poly(methacryl oxyethyl trimethylammonium) and its poly(ethylene glycol)‐grafted analogue as capillary coating materials in electrophoresis

Cationic polyelectrolytes were synthesized and used as semipermanent coating materials for capillaries in electrophoresis. The polyelectrolytes used were a homopolymer of poly(methacryl oxyethyl trimethylammonium chloride) (PMOTAC) and its poly(ethylene glycol) (PEG)‐grafted analogue. Two PMOTAC polyelectrolytes, with molar masses of 85,000 and 300,000 g/mol, and PEG‐grafted PMOTAC with a molar mass of 280,000 g/mol were synthesized and then characterized by size exclusion chromatography (SEC) and nuclear magnetic resonance (NMR) spectroscopy. Attachment of the polyelectrolytes to the wall of the fused silica capillary for electrophoresis caused the electroosmotic flow (EOF) to reverse. The polyelectrolyte coatings were tested over the pH range 2–11 at different buffer ionic strengths, and the most stable and strongest anodic EOFs were obtained at acidic pH values with low ionic strength buffers. Between runs the capillary is merely rinsed for 2 or 3 min with the background electrolyte solution. With the PMOTAC coatings at pH values ≤5, the RSDs of the EOFs were less than 2.9% after 60 injections. The effects of the molar mass of the polycation and of PEGylation of PMOTAC on the interactions between the polycations and basic proteins were studied at acidic pH values. The differences in the effective electrophoretic mobilities, resolution values, and plate numbers of the proteins with the different coatings were due to the EOF, as demonstrated through calculations of reduced mobilities, relative resolution values, and relative plate numbers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2655–2663, 2007     

Sulfoalkylbetaine‐based monolithic column with mixed‐mode of hydrophilic interaction and strong anion‐exchange stationary phase for capillary electrochromatography

A novel monolithic stationary phase with mixed mode of hydrophilic and strong anion exchange (SAX) interactions based on in situ copolymerization of pentaerythritol triacrylate (PETA), N,N‐dimethyl‐N‐methacryloxyethyl N‐(3‐sulfopropyl) ammonium betaine (DMMSA) and a selected quaternary amine acrylic monomer was designed as a multifunctional separation column for CEC. Although the zwitterionic functionalities of DMMSA and hydroxy groups of PETA on the surface of the monolithic stationary phase functioned as the hydrophilic interaction (HI) sites, the quaternary amine acrylic monomer was introduced to control the magnitude of the EOF and provide the SAX sites at the same time. Three different quaternary amine acrylic monomers were tested to achieve maximum EOF velocity and highest plate count. The fabrication of the zwitterionic monolith (designated as HI and SAX stationary phase) was carried out when [2‐(acryloyloxy)ethyl]trimethylammonium methylsulfate was used as the quaternary amine acrylic monomer. The separation mechanism of the monolithic column was discussed in detail. For charged analytes, a mixed mode of HI and SAX was observed by studying the influence of mobile phase pH and salt concentration on their retentions on the poly(PETA‐co‐DMMSA‐co‐[2‐(acryloyloxy)ethyl]trimethylammonium methylsulfate) monolithic column. The optimized monolith showed good separation performance for a range of polar analytes including nucleotides, nucleic acid bases and nucleosides, phenols, estrogens and small peptides. The column efficiencies greater than 192 000 theoretical plates/m for estriol and 135 000 theoretical plates/m for charged cytidine were obtained.     

Capillary electrophoresis in a fused‐silica capillary with surface roughness gradient

The electro‐osmotic flow, a significant factor in capillary electrophoretic separations, is very sensitive to small changes in structure and surface roughness of the inner surface of fused silica capillary. Besides a number of negative effects, the electro‐osmotic flow can also have a positive effect on the separation. An example could be fused silica capillaries with homogenous surface roughness along their entire separation length as produced by etching with supercritical water. Different strains of methicillin‐resistant and methicillin‐susceptible Staphylococcus aureus were separated on that type of capillaries. In the present study, fused‐silica capillaries with a gradient of surface roughness were prepared and their basic behavior was studied in capillary zone electrophoresis with UV‐visible detection. First the influence of the electro‐osmotic flow on the peak shape of a marker of electro‐osmotic flow, thiourea, has been discussed. An antifungal agent, hydrophobic amphotericin B, and a protein marker, albumin, have been used as model analytes. A significant narrowing of the detected zones of the examined analytes was achieved in supercritical‐water‐treated capillaries as compared to the electrophoretic separation in smooth capillaries. Minimum detectable amounts of 5 ng/mL amphotericin B and 5 μg/mL albumin were reached with this method.     

Novel cationic polyelectrolyte coatings for capillary electrophoresis

The use of bare fused silica capillary in CE can sometimes be inconvenient due to undesirable effects including adsorption of sample or instability of the EOF. This can often be avoided by coating the inner surface of the capillary. In this work, we present and characterize two novel polyelectrolyte coatings (PECs) poly(2‐(methacryloyloxy)ethyl trimethylammonium iodide) (PMOTAI) and poly(3‐methyl‐1‐(4‐vinylbenzyl)‐imidazolium chloride) (PIL‐1) for CE. The coated capillaries were studied using a series of aqueous buffers of varying pH, ionic strength, and composition. Our results show that the investigated polyelectrolytes are usable as semi‐permanent (physically adsorbed) coatings with at least five runs stability before a short coating regeneration is necessary. Both PECs showed a considerably decreased stability at pH 11.0. The EOF was higher using Good's buffers than with sodium phosphate buffer at the same pH and ionic strength. The thickness of the PEC layers studied by quartz crystal microbalance was 0.83 and 0.52 nm for PMOTAI and PIL‐1, respectively. The hydrophobicity of the PEC layers was determined by analysis of a homologous series of alkyl benzoates and expressed as the distribution constants. Our result demonstrates that both PECs had comparable hydrophobicity, which enabled separation of compounds with log P_o/w > 2. The ability to separate cationic drugs was shown with β‐blockers, compounds often misused in doping. Both coatings were also able to separate hydrolysis products of the ionic liquid 1,5‐diazabicyclo[4.3.0]non‐5‐ene acetate at highly acidic conditions, where bare fused silica capillaries failed to accomplish the separation.     

Preparation and evaluation of monodispersed,submicron, non‐porous silica particles functionalized with β‐CD derivatives for chiral‐pressurized capillary electrochromatography

Submicron, non‐porous, chiral silica stationary phase has been prepared by the immobilization of functionalized β‐CD derivatives to isocyanate‐modified silica via chemical reaction and applied to the pressurized capillary electrochromatography (pCEC) enantio‐separation of various chiral compounds. The submicron, non‐porous, cyclodextrin‐based chiral stationary phases (sub_μm‐CSP2) exhibited excellent chiral recognition of a wide range of analytes including clenbuterol hydrochloride, mexiletine hydrochloride, chlorpheniramine maleate, esmolol hydrochloride, and metoprolol tartrate. The synthesized submicron particles were regularly spherical and uniformly non‐porous with an average diameter of around 800 nm and a mean pore size of less than 2 nm. The synthesized chiral stationary phase was packed into 10 cm × 100 μm id capillary columns. The sub_μm‐CSP2 column used in the pCEC system showed better separation of the racemates and at a higher rate compared to those used in the capillary liquid chromatography mode (cLC) system. The sub_μm‐CSP2 possessed high mechanical strength, high stereoselectivity, and long lifespan, demonstrating rapid enantio‐separation and good resolution of samples. The column provided an efficiency of up to 170 000 plates/m for n‐propylbenzene.     

Effect of the flow profile on separation efficiency in pressure‐assisted reversed‐polarity capillary zone electrophoresis of anions: Simulation and experimental evaluation

Capillary electrophoresis connected to electrospray ionization mass spectrometry is a promising combination to analyze complex biological samples. The use of sheathless electrospray ionization interfaces, such as a porous nanoelectrospray capillary emitter, requires the application of forward flow (either by pressure or electroosmosis) to maintain the electrospray process. The analysis of solute molecules with strong negative charges (e.g., aminopyrenetrisulfonate labeled glycans) necessitates a reversed‐polarity capillary electrophoresis separation mode, in which case the electroosmotic flow is counter current, thus pressure assistance is necessary. In this study, we compared the effect of forced convection with and without counter electroosmotic flow on the resulting separation efficiency in capillary electrophoresis based on flow profile simulations by computational fluid dynamics technique and by actual experiments. The efficiencies of the detected peaks were calculated from the resulting electropherograms and found approximately 950 000 plates/m for electrophoresis with counter electroosmotic flow, 20 000 plates/m with pressure only (such as would be in open tubular liquid chromatography), and 480 000 plates/m for electrophoresis with simultaneous counter electroosmotic flow and forward pressure assistance, which validates the simulation data.     

Rapid electrophoretic monitoring of the anaesthetic ketamine and its metabolite norketamine in rat blood using a contactless conductivity detector to study the pharmacokinetics

A method of capillary electrophoresis with contactless conductivity detection has been developed for non‐enantioselective monitoring the anaesthetic ketamine and its main metabolite norketamine. The separation is performed in a 15 μm capillary with an overall length of 31.5 cm and length to detector of 18 cm; inner surface of the capillary is covered with a commercial coating solution to reduce the electroosmotic flow. In an optimised background electrolyte with composition 2 M acetic acid + 1% v/v coating solution under application of a high voltage of 30 kV, the migration time is 97.1 s for ketamine and 95.8 s for norketamine, with an electrophoretic resolution of 1.2. The attained detection limit was 83 ng/mL (0.3 μmol/L) for ketamine and 75 ng/mL (0.3 μmol/L) for norketamine; the number of theoretic plates for separation of an equimolar model mixture with a concentration of 2 μg/mL was 683 500 plates/m for ketamine and 695 400 plates/m for norketamine. Laboratory preparation of rat blood plasma is based on mixing 10 μL of plasma with 30 μL of acidified acetonitrile, followed by centrifugation. A pharmacokinetic study demonstrated an exponential decrease in the plasma concentration of ketamine after intravenous application and much slower kinetics for intraperitoneal application.     

Preparation and characterization of a polystyrene/bovine serum albumin nanoparticle‐coated capillary for chiral separation using open‐tubular capillary electrochromatography

Polystyrene (PS) nanoparticles coated by BSA, hereafter denoted as PS/BSA, were prepared and chemically immobilized for the first time onto a capillary inner wall for open‐tubular CEC (OTCEC). EOF and scanning electron micrography were used to characterize the prepared nanoparticle‐coated capillaries. To investigate the performance of the prepared columns in OTCEC, chiral separation of d ,l ‐tryptophan (dl ‐Trp) was performed in monolayer BSA‐modified capillary and PS/BSA nanoparticle‐coated columns. The results indicated that the nanoparticle‐modified column afforded a higher resolution compared with the monolayer type. Rapid enantioseparation of dl ‐Trp (within 3 min) was achieved with the PS/BSA‐immobilized column using an electroosmotic pump‐assisted CEC. Enantiomer separations of other compounds like dl ‐tyrosine and warfarin were also achieved with the column. Besides, run‐to‐run and column‐to‐column repeatabilities of the PS/BSA‐coated column in the chiral separation were systematically introduced.