ABSTRACT
Here,a styrene-based polymer monolithic column poly(VBS-co-TAT-co-AHM)with reversed-phase/hydrophilic interaction liquid chromatography(RPLC/HILIC)bifunctional separation mode was success-fully prepared for capillary electrochromatography by the in situ polymerization of sodium p-styrene sulfonate(VBS)with cross-linkers 3-(acryloyloxy)-2-hydroxypropyl methacrylate(AHM)and 1,3,5-triacryloylhexahydro-1,3,5-triazine(TAT).The preparation conditions of the monolith were optimized.The morphology and formation of the poly(VBS-co-TAT-co-AHM)monolith were confirmed by scanning electron microscopy(SEM)and Fourier transform infrared spectroscopy(FT-IR).The separation perfor-mances of the monolith were evaluated systematically.It should be noted that the incorporation of VBS functional monomer can provide π-π interactions,hydrophilic interactions,and ion-exchange in-teractions.Hence,the prepared poly(VBS-co-TAT-co-AHM)monolith can achieve efficient separation of thiourea compounds,benzene series,phenol compounds,aniline compounds and sulfonamides in RPLC or HILIC separation mode.The largest theoretical plate number for N,N'-dimethylthiourea reached 1.7×105 plates/m.In addition,the poly(VBS-co-TAT-co-AHM)monolithic column showed excellent reproducibility and stability.This novel monolithic column has great application value and potential in capillary electrochromatography(CEC).
ABSTRACT
Biochromatography is a new chromatographic technology with great development potential. It has been widely used in drug screening and biomolecular interaction analysis. The core of this technology is the chromatographic stationary phase of biomolecules. Nowadays, it mainly develops cell membrane chromatography, artificial biomimetic membrane chromatography and the various immobilization strategies to directly immobilizes proteins on the stationary phase carrier. This paper reviews the research progress of new biochromatographic stationary phase and the application of biochromatographic analysis based on new stationary phase. And, the applications of biochromatographic stationary phase and micro biochromatographic analysis system based on monolithic column are prospected.
ABSTRACT
There is a strong need to search for more effective compounds with bone anti-resorptive properties,which will cause fewer complications than commonly used bisphosphonates.To achieve this goal,it is necessary to search for new techniques to characterize the interactions between bone and drug.By studying their interaction with hydroxyapatite (HA),this study used three forms of ceramic materials,two of which are bone-stimulating materials,to assess the suitability of new active substances with anti-resorptive properties.In this study,three methods based on HA in loose form,polycaprolactone/HA (a polymer-ceramic materials containing HA),and polymer-ceramic monolithic in-needle extraction(MINE) device (a polymer inert skeleton),respectively,were used.The affinity of risedronate (a standard compound) and sixteen aminomethylenebisphosphonates (new compounds with potential anti-resorptive properties) to HA was defined according to the above-mentioned methods.Ten monolithic materials based on 2-hydroxyethyl methacrylate/ethylene dimethacrylate are prepared and studied,of which one was selected for more-detailed further research.Simulated body fluids containing bisphosphonates were passed through the MINE device.In this way,sorption-desorption of bisphosphonates was evaluated using this MINE device.The paper presents the advantages and disad-vantages of each technique and its suitability for assessing new active substances.All three methods allow for the selection of several compounds with potentially higher anti-resorptive properties than risedronate,in hope that it reflects their higher bone affinity and release ability.
ABSTRACT
An analytical methodology based on an O-[2-(methacryloyloxy)-ethylcarbamoyl]-10,11-dihydroquinidine (MQD)-silica hybrid monolithic column was developed for the enantioseparation of 9-fluorenylmethoxycarbonyl (FMOC) derivatized amino acids by nano-liquid chromatography. The mo-bile phase was optimized including the apparent pH, content of ACN, and concentration of the buffer to obtain a satisfactory enantioresolution performance. 27 FMOC derivatized amino acids including 19 protein and 8 non-protein amino acids were tested, and 19 out of them were enantiomerically discriminated obtaining baseline separation for 11 of them. Analytical characteristics of the method were evaluated for norvaline and tryptophan in terms of linearity, precision, accuracy, limits of detection (LOD) and quantitation (LOQ) showing good performance to be applied to the enantiomeric determination of these amino acids in dietary supplements. LOD and LOQ values were 9.3 and 31μM for norvaline en-antiomers and 7.5 and 25μM for tryptophan enantiomers, respectively. The contents of D-norvaline and D-tryptophan were below their respective LODs in all the analyzed samples. Quantitation of L-tryptophan and L-norvaline showed good agreement with the labeled contents except for one sample which did not show presence of L-norvaline, contrary to the label indication.
ABSTRACT
Capillary electrochromatography (CEC) is a micro-scale separation technique which is a hybrid between capillary electrophoresis (CE) and liquid chromatography (LC). CEC can be performed in packed, monolithic and open-tubular columns. In recent three years (from 2016 to 2018), enormous attention for CEC has been the development of novel stationary phases. This review mainly covers the development of novel stationary phases for open-tubular and monolithic columns. In particular, some biomaterials attracted increasing interest. There are no significant breakthroughs in technology and principles in CEC. The typical CEC applications, especially chiral separations are described.
ABSTRACT
Molecular simulation was used to study the interaction between template molecule and functional monomer to shorten the optimization time for the functional monomer and the ratio of functional monomer and template molecule.Kaempferol molecularly imprinted polymerization (MIP) monolithic column was therefore synthesized by reversible addition-fragmentation chain-transfer (RAFT) polymerization with dibenzyltrithiocarbonate (DBTTC) and ethyleneglycoldim ethacrylate (EDMA) as RAFT and cross-linking agent, respectively, whereas methacrylic acid (MAA) was the optimal functional monomer with the molar ratio of kaempferol/MAA of 1∶4 from molecular simulation results.The results indicate that molecular simulation is useful to simplify the experimental procedure, and DBTTC as RAFT agent can provide more adjustable and better MIP monolithic column.
ABSTRACT
Objective:To establish a rapid HPLC method for the quantitative determination of 5 saponins ( notoginsenoside R1 , ginsenoside Rg1 ,ginsenoside Re,ginsenoside Rb1 and ginsenoside Rd) in Notoginseng total saponins using a monolithic column. Meth-ods:The analysis was performed on a Merck Chromolith Performance RP-18e column (100 mm × 4. 6 mm,2μm) with gradient elution of acetonitrile and water. The detection wavelength was set at 203 nm. Results:Satisfactory separation of all analytes was obtained in 20 min. All calibration curves showed good linearity within the testing ranges (r≥0.9998). The average recoveries were between 98. 6% and 100. 4%. The RSDs were less than 2. 1% (n=6). Conclusion:The method is efficient and accurate for the quality con-trol of Notoginseng total saponins.
ABSTRACT
Objective:To establish a rapid HPLC method for the quantitative determination of 5 saponins ( notoginsenoside R1 , ginsenoside Rg1 ,ginsenoside Re,ginsenoside Rb1 and ginsenoside Rd) in Notoginseng total saponins using a monolithic column. Meth-ods:The analysis was performed on a Merck Chromolith Performance RP-18e column (100 mm × 4. 6 mm,2μm) with gradient elution of acetonitrile and water. The detection wavelength was set at 203 nm. Results:Satisfactory separation of all analytes was obtained in 20 min. All calibration curves showed good linearity within the testing ranges (r≥0.9998). The average recoveries were between 98. 6% and 100. 4%. The RSDs were less than 2. 1% (n=6). Conclusion:The method is efficient and accurate for the quality con-trol of Notoginseng total saponins.
ABSTRACT
@#Determination of exact total protein bonding quantity is often a key step in the preparation of protein-immobilized chiral monolith. In this study, we developed and evaluated a bovine serum albumin(BSA)modified monolith based on glycidyl methacrylate(GMA)and ethylene dimethacrylate(EDMA)for chiral separation. The epoxy groups of the polymer were used directly for the covalent bonding of BSA. A Coomassie brilliant blue(CBB)protein assay(Bradford method)was established to determine the protein bonding quantity, and the influence of some key aspects such as ionic strength, pH value and reaction time were studied. The method was validated with respect to linearity, precision, accuracy and robustness. The maximum amount of immobilized BSA was 11. 90 mg/g, obtained using 65 ∶35 cyclohexanol/dodecanol as the porogen. The monolith was successfully applied in the chiral separation of R/S-warfarin and D/L-tryptophan in only 1-20 min. Furthermore, the chromatographic conditions like pH and organic additive of the mobile phase were optimized. The chiral separation performance of this BSA-immobilized monolith is positively correlated to the protein bonding quantity.
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Objective To develop a rapid SERS detection method based on monolithic column for detection of dye adul-terated natural indigo .Methods The dyes in natural indigo were extracted and mixed with silver colloid .The spectra were re-corded after applying the mixture solution to the monolithic column since the intertwined pores in monolithic column could con-tribute for the distribution of silver nanoparticles .Results SERS signals of malachite green dyed natural indigo at quantity as low as 500 μg/kg could be obtained .Conclusion This simple ,fast and specific SERS detection method based on monolithic col-umn could be used for rapid detection of stained natural indigo .
ABSTRACT
The build-in low-pressure monolithic column combined with hydride generation atomic fluorescence spectrometry ( HG-AFS ) was employed for speciation analysis of fish meat. The sample pretreatment and separation approach could be accomplished within 30 min. The proper amount of fish sample was weighed and smashed into puree. The extraction solution composed of 10% HCl, 1% thiourea, and 0. 15% KCl was added before loaded into the automatic temperature controlled vertex system with 2000 r/min. The sample solution was separated through Merck monolithic column, with 3% ( V/V) acetonitrile, 30 mmol/L amonium acetate and 0. 03%(V/V) 2-mercaptoethanol (2-ME) as the eluent. The after-column eluent was digested by novel UV digestion device with pipeline sintered into the lamp, and then detected by hydrid-generation AFS. The rapid LC separation enabled fast mercury speciation of fish sample within 10 min. The different UV lamp digestion effects, eluent components, carrier gas, shield gas, lamp current, as well as PMT working power was optimized. Under the optimal conditions, the robust system achieved detection limits (DL) of 0. 15 μg/L and 0. 14 μg/L for methylmercury and HgⅡ, respectively. The RSD (n=7) was less than 5%, the linear correlation coefficient was 0 . 999 , and the matrix spiked recovery was in the range of 85%-110% for Hg speciation. This method was used for the determination of Hg speciation in fish and soil samples, and was proofed to be a reliable, easy approach for daily inspection.
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A novel silica monolithic stationary phase functionalized with butylaminopropyl ligands for capillary electrochromatography(CEC) has been presented. The monolithic capillary columns were prepared by a sol-gel) process and subsequent a chemical modification. The amino groups on the surface of the stationary phase are meant to generate a substantial anodic electroosmotic flow (EOF). The butyl and propyl groups provide) hydrophobic properties. To evaluate the column performance, effects of buffer pH and organic modifier content on the EOF and electrochromatographic retention behavior of alkylbenzenes, organic acids and anilines were investigated. The monolithic stationary phase exhibited reversed phase (RP) chromatographic behavior toward neutral solutes. The model organic acid anion solutes were separated by the mixed mode mechanism, which comprised RP interaction, weak anion-exchange, and electrophoresis. Basic compounds such as anilines) were well separated on the butylaminopropyl silica monolithic column without peak tailing.
ABSTRACT
Melamine is a kind of triazine compound and the fluorescence of it can get enhanced in the presence of cationic surfactant in weak alkaline medium. A new fluorescent spectrophotometry based on this principle) has been developed to determine melamine under the optimum conditions such as Tris-HCl buffer solution), pH 8.0 and with CTMAB as sensitizing agent. The linear range, detection limit and relative standard deviation were 25-1000 μg/L, 19 μg/L and 1.6%,respectively. The samples were pretreated according to the solid phase extraction monolithic column to carry out the detection of real milk. This method is simple, rapid and accurate. It can be used to screen and detect the milk samples primarily.