Chromatographic separation and recovery of Zn(Ⅱ)and Cu(Ⅱ)from high-chlorine raffinate of germanium chlorination distillation

An anion-exchange-based chromatographic separation approach was developed to selectively recover zinc and copper from the high-chlorine raffinate generated in the process of germanium chlorination distillation using 717 resins based on the coordination difference between Zn^(2+)/Cu^(2+)and Cl^(-).The theoretical calculation and spectroscopic analyses suggested that the coordination between Zn^(2+)and Cl^(-)is much stronger than that between Cu^(2+)and Cl^(-),and the Cl-concentration significantly affects Zn(Ⅱ)and Cu(Ⅱ)species.The factors involving Cl-concentration,resin dosage,shaking speed,and temperature were investigated to determine the optimal condition,and the maximum separation factor of Zn/Cu reached as high as 479.2.The results of the adsorption isotherms,adsorption kinetics,SEM,FTIR,and XPS analyses indicated that the process followed the monolayer uniform chemisorption.Through the continuous adsorption experiments,Zn(Ⅱ)and Cu(Ⅱ)in the high-chlorine raffinate were separately recovered,allowing the reuse of residual waste acid and germanium.

CHROMATOGRAPHIC SEPARATION ON GRAPHITE OF FULLERENE-C_(60) AND-C_(70)

The mixture of fullerene—C_(60) and —C_(70) was successfully separated in larger amount by liquid chromatogra- phy on graphite column.The column was first eluted with a mixture of hexane and toluene,and then with toluene.The eluates were monitored by UV/visible absorption spectroscopy.Graphite column shows high perfor- mance for separation.and much larger quantities of pure C_(60) can be easily obtained. The synthesis of fullerenes(C_(60) and C_(70))in macroscopic quantities has stimulated scientists to study on the method for separating C_(60) and C_(70).Because of the poor solubility of fullerenes C_(60)/C_(70) in most organic solvents,the separation of C_(60) and C_(70) proved to be a challenging task.Most attempts at the separation have used silica and alu- mina as the stationary phase and a mixture of hexane and benzene(or toluene)as the mobile phase. Fullerenes,however,have only limited solubility in hexane,these separations are usually only achieved by limit- ing the amount of sample to a few milligrams.The hexane-silica technique using phenylglycine based HPLC columns appears to offer good separation,but only for submilligram amounts. The use of graphite powder as the stationary phase in liquid chromatography is an advanced separation tech- nique for fullerenes C_(60)/C_(70).The technique is based on that the fullerene-C_(60) is different from C_(70) in the de- gree of electron delocalisation,and C_(60) is much less diamagnetic than C_(70).It is expected that the dissimilarity will cause the C_(60)/C_(70) molecules to exhibit different interactions with graphite,and can be separated from each other on this basis.

CHROMATOGRAPHIC SEPARATION OF THE ENANTIOMERS OF 3-PHENYL-1,2-EPOXYETHANE AND 1-PHENYL-1-PROPANOL ON A FUSED SILICA CAPILLARY COLUMN COATED WITH PERBENZYL-β-CYCLODEXTRIN

A β-cyclodextrin derivative, perbenzyl-β-cyclodextrin, was prepared and used as a chiral stationary phase for capillary gas chromatography. Using FID detector and the column temperature between 70 and 80℃, the chiral separations of racemic 3-phenyl-1, 2-epoxyethane and 1-phenyl-1-propanol on a 14m×0.23mm I. D. fused silica column with the β-cyclodextrin derivative were carried out and the optical purities of optically active 1-phenyl-1-propanol samples prepared by asymmetric synthesis were determined.

HIGH-PERFORMANCE LIQUID CHROMATOGRAPHIC SEPARATION OF FULLERENES

High-performance liquid chromatographic systems for the separation of buckminsterfullerene(C_(60)) and related fullerene C_(70) were investigated with methanol/benzene or methanol/toluene (35/65-60/40 in Ⅴ/Ⅴ) as eluant in C18 reversed phase column. The system is suitable for fast analysis of fullerenes at lower percentage of methanol, and repeatly large scale perparation at higher percentage of methanol.

Thin-Layer Chromatographic Separation of Amino Acid Enantiomers using Ligand Exchange

Silica gel thin-layer plates covered with L-arginine and copper acetate were used for the separation of amino acid enantiomers, The chromatographic selectivity and the effects of plate different preparation methods, sample molecular structure and solvent compositions on resolution performance were also discussed.

Octadecylamine and glucose-coderived hydrophobic carbon dots-modified porous silica for chromatographic separation

A hydrophobic carbon dots(Glc-OCDs)derived from octadecylamine and glucose were successfully synthesized for the first time and then grafted onto the porous silica surface by the“Nano-on-Micro”strategy,which was served as a new stationary phase(Sil-Glc-OCDs)for reversed-phase liquid chromatography.The structure of this stationary phase was carefully verified by laser scanning confocal microscope,Fourier transform infrared spectrometry,elemental analysis,contact angle measurement,etc.Several analytes including seven polycyclic aromatic hydrocarbons,eight alkylbenzenes,eight phenols and seven sulfonamides can be well separated on this stationary phase.Better separation performance for certain analytes over commercial C_(18) column was obtained.Interestingly,this stationary phase exhibited excellent chromatographic selectivity in the separation of the isomers of tert‑butylbenzene,sec‑butylbenzene,isobutylbenzene and n-butylbenzene.In addition,this new Sil-Glc-OCDs column was also applied for detection of calycosin-7-glucoside,ononin,calycosin,formononetin,genistein and isorhamnetin in the extract of Radix Astragali,which were found that the concentration was 0.15 g/L,0.088 g/L,0.14 g/L,0.086 g/L,0.18 g/L and 0.29 g/L,respectively.We believe that this CDs-grafted silica materials are promising for chromatographic separation.

DETERMINATION OF THERMODYNAMIC AND KINETIC PARAMETERS OF LARGE SCALE CHROMATOGRAPHIC SEPARATION OF SUGAR AND REDUCING SUGAR

The parameter identification model of largr scale chromatography separation process is proposed. The Phase equilibrium constants and lumped mass transfer coefficients of sugar and reducing sugar adsorption on D1, D2 and D3 resins as well as the axial dispersion coefficients of the fluid through packed columns are determined by means of the pulse-response experiment technique with an inert substance as a tracer and the chromatography measuring technique. The elution curve calculated from these parameters is good agreement with the experimental elution curve. The sensitivity analysis of these parameters is carried out, and the ressult shows that the elation curves of chromatography separation are more sensitive to the variations Of the Phase equilibrium relationship than to the variation of the axial dispersion as well as the lumped mass transfer coefficients.

Separation and Identification of Glutamine Peptides from Defatted Soybean Meal by Enzymatic Hydrolysis

Glutamine peptides were obtained from defatted soybean meal by enzymatic hydrolysis using a combination of Protamex~? and trypsinase. The results showed that the extent of hydrolysis and the concentration of Gln peptides in the hydrolysate were 22.02%and 6.05 mmol/L, respectively. The hydrolysates were fractionated by size-exclusion chromatography on a Sephadex G-15 into five major fractions(GelF1–GelF5). The peptide(GelF1) fraction with the highest glutamine peptide content(51.8%) was further evaluated to determine its molecular weight distribution. Most(92.37%) peptides were less than 1 000 Da. Glutamic acid and glutamine were the most abundant amino acids, accounting for up to 12.98% of the total amino acid content. In addition, the total amino acid content in GelF1 was higher than that in GelF2 and GelF3.

Isolation of lignosulfonate with low polydispersity index

Lignosulfonate with low polydispersity index of 1.178-1.210 was isolated by gel column chromatography of Sephacryl S-100 eluted with 0.2 mol/L of NaNO3 aqueous solution,whereas nearly monodisperse ligosulfonate fraction with polydispersity of 1.0(57 can be obtained after chromatographic separation twice.This method provides an available approach to investigate the structure and characteristics of lignosulfonate.

Exploiting styrene-maleic acid copolymer grafting chromatographic stationary phase materials for separation of membrane lipids

High performance liquid chromatography-mass spectrometry is one of the most commonly used strategies for lipid analysis.The development of versatile chromatographic stationary phases to meet the increasing demands for separation of complex lipids is very important.Styrene-maleic acid(SMA)copolymer is an amphiphilic polymer,which has been proven to have the ability to solubilize lipid molecules of various structures.In this study,styrene-maleic anhydride copolymer coated silica was first prepared by the thiol-ene click reaction.With L-cysteine hydrochloride or dodecanol as the post-modification reagents,Sil-SMA-amino acid and Sil-SMA-dodecanol stationary phase materials were further successfully fabricated via nucleophilic ring-opening reaction.The Fourier-transform infrared,thermogravimetric analysis,and elemental analysis results confirmed the two stationary phase materials were successfully prepared.Furthermore,both the Sil-SMA-dodecanol column and the Sil-SMA-amino acid column possessed reversed-phase/hydrophilic interaction/ion exchange mixed-mode retention mechanisms.The column efficiency of the Sil-SMA-derivatives columns reached 77,300 N/m.Based on the mixed-mode retention characteristics,the Sil-SMA-derivatives columns achieved both the lipid classes and species separation via a single column.The Sil-SMA-amino acid column was further successfully used to separate lipid extract from gastric cancer cell membrane.All these results demonstrated that the SMA-based stationary phase materials have a good potential for use in lipid separation.

Dynamic separation of Xe and Kr by metal-organic framework and covalent-organic materials： a comparison with activated charcoal

We systematically investigate dynamic separation of Xe and Kr at room temperature using four representative porous materials(Cu-BTC, ZIF-8, COP-4 and activated carbon(AC)). Results indicate that among the four materials, Cu-BTC not only shows the highest retention volume per gram(V_g=788 m L g^(-1), which is 1.8 times of activated carbon(436 m L g^(-1))) under flowing condition, but also can separate 350 ppm Xe from 35 ppm Kr mixture in air with a high Xe/Kr selectivity of 8.6 at room temperature and 200 k Pa, due to its suitable pore morphology, open metal sites, small side pockets in the framework. Moreover, the Cu-BTC also performs well on individual separation of Xe, Kr, CO_2 from five-component gas mixture(Xe:Kr:CO_2:Ar:N_2= 1:1:1:1:0.5, V/V) and has the longest retention time for Xe(20 min) in gas chromatographic separation, suggesting that it is a good candidate for potential applications as polymeric sieves.

Nano-sized stationary phase packings retained by single-particle frit for microchip liquid chromatography

Modern chromatography is increasingly focused on miniaturization and integration. Compared to conventional liquid chromatography, microfluidic chip liquid chromatography(microchip-LC) has the potential due to its zero-dead volume connection and ease of integration. Nano-sized packings have the potential to significantly enhance separation performance in microchip-LC. However, their application has been hindered by packing difficulties. This study presents a method for packing nano-sized silica particles into a microchannel as the stationary phase. The microchip-LC packed column was prepared by combining the weir and the porous silica single-particle as frit to retain the packing particles. A surface tensionbased single-particle picking technique was established to insert porous single-particle frit into glass microchannels. Additionally, we developed a slurry packing method that utilizes air pressure to inject nano-sized packing into the microchannel. Pressure-driven chromatographic separation was performed using this nano-packed column integrated into a glass microchip. The mixture of four PAHs was successfully separated within just 8 min using a 5 mm separation channel length, achieving high theoretical plates(10~6plates/m). Overall, these findings demonstrate the potential of utilizing nano-sized packings for enhancing chromatographic performance in microchip systems.

Apigenin-7-O-β-D-glycoside isolation from the highly copper-tolerant plant Elsholtzia splendens

Elsholtzia splendens （Lamiaceae） is a copper-tolerant plant species growing on copper deposits in the south of China. Chromatographic separation of n-BuOH extracts from the flowering aerial biomass afforded apigenin- 7-O-β-D-glycoside, using macroporous resin, SephadexTM LH-20 gel, polyamide resin as well as preparative high- performance liquid chromatography （P-HPLC） columns. Chemical structure was elucidated using HPLC/ESI-MS （electrospray ionization-mass spectrometry）, Fourier transform infrared （FTIR）, and 1D- and 2D-nuclear magnetic resonance （NMR）. Apigenin-7-O-β-D-glycoside could be the post-harvesting product from E. splendens biomass.

Preparation and Evaluation of Silicon Quantum Dots-Bonded Silica Stationary Phase for Reversed-Phase Chromatography

In this paper,silicon quantum dots(SiQDs)with green fluorescence are synthesized by solvothermal reaction of 3-(2,3-epoxypropoxy)propyltrimethoxysilane(GPTMS)and ethylenediaminetetraacetic acid(EDTA),and then SiQDs are bonded to the surface of silica to obtain a new nano-on-micro stationary phase(SiO_(2)-SiQDs)for reversed-phase chromatography.The successful preparation of SiO_(2)-SiQDs stationary phase is demonstrated by a variety of characterizations,such as transmission electron microscopy,laser confocal microscopy,elemental analysis and Fourier infrared spectroscopy.In addition,the chromatographic performance of the prepared stationary phase is evaluated and it shows good separation performance for non-polar substances such as alkylbenzene,aniline and polycyclic aromatic hydrocarbons in reversed-phase liquid chromatography.It is also verified that the stationary phase has good methyl selectivity and shape selectivity.More interestingly,the separation of prednisolone and hydrocortisone isomers can also be achieved at a low ratio of organic solvents,indicating that this new stationary phase has a good application prospect in isomer separation.

Two-dimensional MOF Cu-BDC nanosheets/ILs@silica core-shell composites as mixed-mode stationary phase for high performance liquid chromatography

Here,silica microspheres were decorated with two-dimensional metal-organic frameworks(2 D MOFs)nanosheets and ionic liquids,and evaluated as the mixed-mode stationary phase for chromatographic separation.The ionic liquids were used to assist the synthesis of 2 D MOFs nanosheets,and also acted as adhesives among the nanosheets and silica.In contrast with the 2 D MOFs-based column without ionic liquids and commercial columns,the prepared column exhibited enhanced chromatographic separation performance for partially hydrophilic compounds such as alkaloids,sulfonamides and antibiotics,etc.In addition to excellent chromatographic repeatability and stability,it has also been verified that the composites could be easily and repeatedly prepared.The relative standard deviation of the retention time of the same type of analyte between the three batches of materials was ranging from 0.21%to 1.7%.In short,these results indicated that the synthesized composites were promising separation material for liquid chromatography,which made it possible to broaden the application of 2 D MOFs in the field of chromatography.

In-situ carbonizing of coal pitch on the surface of silica sphere as quasi-graphitized carbon stationary phase for liquid chromatography

A novel chromatography stationary phase with a quasi-graphitized carbon modified shell has been developed. Coal pitch was directly carbonized on the surface of porous silica with in-situ carbonization. The carbonized coal pitch coating exhibits some degree of graphitization with a 78 nm-thick layer on the surface of silica and a 0.5 nm-thick layer on the inner surface of the mesopores. Based on the special structure of the graphitized carbon coating, the novel stationary phase can provide multiple interactions such as hydrophobic interaction, π-π interaction and dipole-dipole interaction. The novel composite material exhibited unique separation selectivity and excellent separation efficiency for polar compounds, including imidazoles, nucleosides and pesticides. Besides, the packed column also exhibited great repeatability with the RSDs of the retention time of nucleosides between 0.07%-0.50%(n = 5). Finally, satisfied result was achieved in the separation of fullerenes on the new column, suggesting the great potential in the industrial-scale purification of fullerenes.

Ionic Liquid 1-Vinyl-3-dodecylimidazole Bromide Embedded Hybrid Monolithic Column and Its Versatile Post-modification with Amino Acids

The amino acids post-modified ionic liquids-based hybrid monolithic columns were successfully developed.For the first step,using 1-vinyl-3-dodecylimidazole bromide(VDI·Br)and polyhedral oligomeric silsesquioxane methacryl substituted(POSS-MA)as monomer and crosslinking agent,the monolithic POSS-VDI matrix material was polymerized in 100μm capillary.The prepared POSS-VDI column is of ion-exchange/reverse-phase mixed-mode retention characteristics.The column e fficiency reached 137,000 N/m for thioureas.The POSS-VDI column has also been successfully applied to recognize and analyze the eff ective components of Traditional Chinese Medicines Fangji and the Root of Kudzu Vine.Furthermore,based on its good chromatographic performances,in the second step,amino acids L-Proline(L-Pro),Glycine(Gly)or DLPhenylalanine(DL-Phe)were further exploited as the anion exchangers to post-modify the POSS-VDI column.The new POSS-VDI-Pro,POSS-VDI-Gly and POSS-VDI-Phe columns exhibited diff erent separation selectivity for the complex egg white protein sample.The present work provides a good route to fabricate versatile amino acids and ionic liquids modified monolithic columns with good separation selectivity.