Column Packing Material Research Articles

Rice straw modified by click reaction for selective extraction of noble metal ions

Rice straw was modified by azide–alkyne click reaction in order to realize selective extraction of noble metal ions. The ability of the modified straw to adsorb Pd2+ and Pt4+ was assessed using a batch adsorption technique. It was found that the sorption equilibrium could be reached within 1h and the adsorption capacity increased with temperature for both Pd2+ and Pt4+. The maximum sorption capacities for Pd2+ and Pt4+ were respectively attained in 1.0 and 0.1mol/L HCl. The modified straw showed excellent selectivity for noble metal ions in comparison to the pristine straw. In addition, the modified straw was examined as a column packing material for extraction of noble metal ions. It was indicated that 1.0mL/min was the best flow rate for Pd2+ and Pt4+. The modified straw could be repeatedly used for 10 times without any significant loss in the initial binding affinity.

Calcium isotope fractionation in liquid chromatography with benzo-18-crown-6 resin in aqueous hydrobromic acid medium

Liquid chromatography operated in a breakthrough mode was employed to study calcium isotope fractionation in the aqueous hydrobromic acid medium. Highly porous silica beads, the inner pores of which were embedded with a benzo-18-crown-6 ether resin, were used as column packing material. Enrichment of heavier isotopes of calcium was observed in the frontal part of respective calcium chromatograms. The values of the isotope fractionation coefficient were on the order of 10−3. The observed isotope fractionation coefficient was dependent on the concentration of hydrobromic acid in the calcium feed solution; a higher HBr concentration resulted in a smaller fractionation coefficient value. The present calcium isotope effects were most probably mass-dependent, indicating that they mostly came from isotope effects based on molecular vibration. Molecular orbital calculations supported the present experimental results in a qualitative fashion. Chromatography operated in aqueous HBr media is a better system of Ca isotope separation than that operated in aqueous HCl media.

Removal of hexavalent chromium from water using Fe-grown carbon nanofibers containing porous carbon microbeads

The present study describes the adsorption of hexavalent chromium (Cr(VI)) ions using the Fe nanoparticle (NP)-containing carbon nanofibers (CNFs) grown on porous carbon microbeads (∼0.5mm) as adsorbents. The porous carbon beads were produced by carbonization and activation of the phenolic precursor-based polymeric beads synthesized by suspension polymerization. The Fe NPs were in situ incorporated within the polymeric beads during polymerization. CNFs were grown inside the beads by chemical vapor deposition using the Fe NPs as the metal catalyst and benzene as the carbon source. Adsorption tests were performed to determine the removal efficiency of the adsorbents for Cr(VI) over the concentration range of 10–150ppm in water under batch and dynamic (flow) conditions. The results revealed that the prepared adsorbents had significant adsorption capacity (∼41mgg−1) for Cr(VI), which was comparable or larger than that of the materials discussed in the literature. Moreover, the uptake of the solute during flow was approximately the same as that obtained under batch conditions, signifying negligible mass transfer resistances. The Fe-CNF-grown porous carbon beads prepared in this study may be used as packing materials in columns for the effective removal of Cr(VI) ions from wastewater under flow conditions.

Molecular weight distribution characterization of hydrophobe-modified hydroxyethyl cellulose by size-exclusion chromatography

Size-exclusion chromatography (SEC) of hydrophobe-modified hydroxyethyl cellulose (HmHEC) is challenging because polymer chains are not isolated in solution due to association of hydrophobic groups and hydrophobic interaction with column packing materials. An approach to neutralize these hydrophobic interactions was developed by adding β-cyclodextrin (β-CD) to the aqueous eluent. SEC mass recovery, especially for the higher molecular weight chains, increased with increasing concentration of β-CD in the eluent. A β-CD concentration of 0.75wt% in the eluent was determined to be optimal for the HmHEC polymers studied. These conditions enabled precise determinations of apparent molecular weight distributions exhibiting less than 2% relative standard deviation in the measured weight-average molecular weight (MW) for five injections on three studied samples and showed no significant differences in MW determined on two different days. The developed technology was shown to be very robust for characterizing HmHEC having MW from 500kg/mol to 2000kg/mol, and it can be potentially applied to other hydrophobe-modified polymers.

Octadecylamine-attached poly(3-chloro-2-hydroxypropyl methacrylate-co-ethylene dimethacrylate) microspheres as a new stationary phase for microbore reversed phase chromatography

Monosized-porous polymethacrylate based hydrophilic microspheres with reactive chloropropyl functionality were produced as a starting material for the synthesis of an octadecylated stationary phase for microbore-reversed phase chromatography. A seeded polymerization method based on a new functional monomer, 3-chloro-2-hydroxypropyl methacrylate (HPMA-Cl), was used with a methacrylic crosslinking agent, ethylene dimethacrylate (EDMA). The presence of a reactive functionality (i.e. chloropropyl moiety) in the poly(HPMA-Cl-co-EDMA) microspheres allowed the covalent attachment of a hydrophobic ligand, octadecylamine (ODA), onto the particles via a single stage nucleophilic substitution reaction. ODA-attached poly(HPMA-Cl-co-EDMA) microspheres were slurry packed into a microbore column. Alkylbenzenes and phenols were successfully separated with the theoretical plate numbers up to 60 000 plates per m. ODA-attached poly(HPMA-Cl-co-EDMA) microspheres are good candidates to be an alternative column packing material to the currently available packings for microbore-reversed phase chromatography (μ-RPLC).

Equipment design for thermal cycling absorption process column efficiency test

In order to support the tritium production and recycling in the fuel cycle system of fusion reactors, the thermal cycling absorption process (TCAP), which is a semi-continuous chromatographic process for hydrogen isotope separation, has been developed for years. The hydrogen isotopes separation capacity mostly depends on the efficiency of the separation columns, therefore, evaluating different column structure designs and packing materials for their separation efficiency is significative. In this work, a unique design of separation column apparatus with the hot/cold cycling system has been developed. Its unique feature is the different separation columns can be changed for testing several factors such as particle size of packing material, fill density and uniformity, column structure on the influence of the column efficiency. Moreover, the methods to measure efficiency of the separation column have been introduced. The experimental results show that the displacement chromatographic method is more suitable for this apparatus to analyze the column efficiency.

Separation and Speciation of Iron Ions by Using Colorimetric Hydrogels

In this study, Fe3+ ion selective N-(Rhodamine-6G)lactam-N'-acryloyl-ethylenediamine (RH6GAC) monomer was synthesized. Then, p(Acrylamide-co-N-(Rhodamine-6G)lactam-N'-acryloyl-ethylenediamine) (p(AAm-co-RH6GAC)) and p(2-hydroxyethyl- methacrylate-co- N-(Rhodamine-6G)lactam-N'-acryloyl-ethylenediamine) (p(HEMA-co-RH6GAC)) colorimetric hydrogels were synthesized by using acrylamide (AAm) and 2-hydroxyethylmethacrylate (HEMA) as primary monomers. FT-IR, SEM, polymerization yield and swelling characterizations were conducted for the resulting hydrogels. Then, these hydrogels were used in selective absorption of Fe3+ ions from aqueous media. The hydrogels, which could absorb Fe3+ ions selectively from a mixture of metal ions, were used as column packing material. The solutions containing Fe2+ and Fe3+ ions at different concentrations were separated at a rate of 97.7 ± 0.7%.

Micrometer-sized mesoporous diamond spherical particles

Micrometer-sized porous diamond spherical particles (PDSPs) were fabricated from nanodiamond (ND) particles using spray drying and microwave plasma-assisted chemical vapor deposition (MPCVD). Nitrogen gas sorption measurement revealed that the PDSP fabricated from 5 nm detonation ND particles had a Brunauer–Emmett–Teller (BET) surface area of ca. 300 m 2 g − 1 and a narrow pore diameter distribution around 10 nm. Nitrogen sorption analysis of PDSP fabricated from various ND particle sizes (diameters from 20 to 50 nm) showed that the BET surface area decreased (200–85 m 2 g − 1 ) and the average pore diameter increased (4.6–9.3 nm) as the ND diameter increased from 20 to 50 nm. Calculation with a simple model revealed that the pores of the PDSP were derived from the interparticle space of the NDs. The PDSP was durable to immersion in aqueous solutions of HF and NaOH, which indicates the extremely high chemical stability of the diamond-based mesoporous material. The PDSP surface was modified with octadecyl groups using a photochemical method. A column packed with the modified PDSP was successfully employed in a reverse phase high performance liquid chromatography (HPLC) column, and the successful separation of organic compounds was demonstrated with a water/acetonitrile mixture mobile phase. • Micrometer-sized mesoporous diamond spherical particles were fabricated. • Pore size can be controlled by nanodiamond particle size used. • The porous diamond spherical particle (PDSP) exhibited extreme chemical stability. • The modified PDSP was applied to HPLC column packing material.

Synthesis and application of ion-imprinted interpenetrating polymer network gel for selective solid phase extraction of Cd2+

In the present work, a new Cd2+-imprinted sorbent with interpenetrating polymer network (IPN) structure has been prepared by free radical/cationic hybrid photopolymerization. The ability of the imprinted gel to adsorb Cd2+ was assessed using a batch adsorption technique. The sorption equilibrium data agreed well with the pseudo-second-order kinetic model and the Freundlich isotherm. The study on thermodynamic parameters suggested that the Cd2+ sorption was a spontaneous, exothermic process with further decrease in the degree of freedom. The adsorption mechanism studied by Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) indicated that Cd2+ adsorption was mainly through interactions with the NH, OH, CO and CO groups. In addition, the imprinted gel was examined as a column packing material for solid phase extraction of Cd2+. The imprinted gel showed higher selectivity for Cd2+ in comparison to the non-imprinted gel. Relative selectivity coefficients for Cd2+/Cu2+, Cd2+/Ni2+ and Cd2+/Pb2+ were 7.64, 7.58 and 7.59 respectively. The relative standard deviation of the seven replicate determinations of Cd2+ was 1.7%. With preconcentration of 100mL samples, detection limit of 0.5μg/L was determined. The developed method was successfully applied to the determination of trace Cd2+ in various natural water samples with satisfactory results.

Ag–Fe3O4 nanocomposites@chitin microspheres constructed by in situ one-pot synthesis for rapid hydrogenation catalysis

Ag–Fe3O4@chitin microspheres were developed as a retrievable catalyst and a potential chromatography column packing material for organic synthesis.

Calcium isotope fractionation in liquid chromatography with crown ether resin in methanol medium

Breakthrough mode liquid chromatography was employed to investigate calcium (Ca) isotope fractionation in methanol medium. Highly porous silica beads, the inner pores of which were embedded with a benzo-18-crown-6 ether resin, were used as column packing material. Enrichment of heavier isotopes of Ca was observed in the frontal part of the respective Ca chromatograms. The values of the isotope fractionation coefficient (ϵ) were in the order of 10−3 at 25 °C. Use of methanol as solvent has little advantage over the aqueous system as far as the values of ϵ are concerned. However, a substantial improvement was observed concerning the adsorption capacity of the crown ether resin for Ca ions. Molecular orbital calculations supported the present isotopic results in a qualitative fashion.

Synthesis, characterization and application of a novel ion-imprinted polymer for selective solid phase extraction of copper(II) ions from high salt matrices prior to its determination by FAAS

A new Cu(II)-imprinted sorbent has been prepared by using 5-methyl-2-thiozylmethacrylamide (MTMAAm). The monomer of Cu(II)–MTMAAm complex was synthesized and copolymerized in the presence of ethyleneglycol dimethacrylate cross-linker via bulk polymerization method. The resulting Cu(II)-imprinted polymer was characterized by FT-IR spectroscopy and scanning electron microscopy (SEM). Copper ions were removed from the polymer with 1.0molL−1 HNO3 and determined by flame atomic absorption spectrometry (FAAS). The imprinted polymer showed higher selectivity for Cu(II) in comparison to the non-imprinted polymer. Relative selectivity coefficients (k′) for Cu(II)/Zn(II), Cu(II)/Ni(II) and Cu(II)/Co(II) were 9.1, 14.8 and 26.6, respectively. The imprinted polymer was examined as a column packing material for solid phase extraction of Cu(II) from various matrices. The effects of solution pH, acid eluents and interfering ions were investigated. The poylmer possesses selective extraction of Cu(II) within pH range from 5.0 to 6.5. The relative standard deviation and limit of detection (3s) of the method were evaluated as 1.4% and 0.9µgL−1, respectively. The accuracy of the method was verified by analysis of two certified reference materials (CWW-TM-D and SRM 3280) and then applied to the determination of Cu in seawater, lake water and tap water samples, and hemodialysis concentrates and multivitamin/multielement supplements.

Adsorption and separation of proteins by collagen fiber adsorbent

The separation of proteins is a key step in biomedical and pharmaceutical industries. In the present investigation, the collagen fiber adsorbent (CFA) was exploited as column packing material to separate proteins. Bovine serum albumin (BSA), bovine hemoglobin (Hb) and lysozyme (LYS) that have different isoelectric points (pIs) were selected as model proteins to investigate the separation ability of CFA to proteins. In batch adsorption, the adsorption behaviors of these proteins on CFA under different pHs and ionic strengths indicated that the electrostatic interaction plays a predominant role in the adsorption of proteins on CFA. CFA exhibited high adsorption capacity to Hb and LYS. In column separation, the proteins were completely separated by adjusting pH and ionic strength of the eluent. The increase of flow rate could reduce the separation time with no influence on the recovery of protein in the experimental range. The protein recovery was higher than 90% even when the CFA column was re-used for 4 times in separation of BSA and LYS, and the retention time of BSA or LYS was almost constant during the repeated applications. In addition, as a practical application, LYS was successfully separated from chicken egg white powder by CFA column.

Application of LC–MS/MS for quantitative analysis of glucocorticoids and stimulants in biological fluids

Liquid chromatography tandem mass chromatography (LC–MS/MS) is an important hyphenated technique for quantitative analysis of drugs in biological fluids. Because of high sensitivity and selectivity, LC–MS/MS has been used for pharmacokinetic studies, metabolites identification in the plasma and urine. This manuscript gives comprehensive analytical review, focusing on chromatographic separation approaches (column packing materials, column length and mobile phase) as well as different acquisition modes (SIM, MRM) for quantitative analysis of glucocorticoids and stimulants. This review is not meant to be exhaustive but rather to provide a general overview for detection and confirmation of target drugs using LC–MS/MS and thus useful in the doping analysis, toxicological studies as well as in pharmaceutical analysis.

Application of two new LC–ESI–MS methods for improved detection of intact polar lipids (IPLs) in environmental samples

Intact polar lipid distributions have become a valuable tool for the study of microbial ecosystems. In order to expand the detection and interpretation of the presence of these lipids, improved analytical methods are needed. Therefore, two high pressure liquid chromatography–electrospray ionization tandem mass spectrometry (HPLC–ESI–MS2) methods, based on hydrophilic interaction chromatography (HILIC) and reversed phase (RP) chromatography were developed, taking advantage of new chromatographic possibilities such as smaller particle size and recently developed column packing material. Both were optimized to cover the broad range of compounds found in environmental samples and to cope with the associated complex sample matrices. The capabilities of the methods were tested on pure standards and an environmental sample. Both methods offer improved peak resolution and detection limit, and reduced chromatographic background at twofold shorter run time compared with the previous method based on a diol column. The HILIC method offers separation according to lipid class similar to a diol column, so can be recommended for lipid fingerprinting. The method based on RP separation offers the unique possibility of analyzing intact polar lipids and core lipids in the same chromatographic run and an alternative mode of lipid separation based mainly on side chain structure. The method is especially suitable for separation of compounds based on side chain length, degree of saturation and/or presence of acyl/ether bonds. The combination of both newly developed chromatographic methods provides a powerful tool for the analysis of lipid distributions in environmental samples at ultra-low concentration.

Synthesis and characterization of new optically active poly(amide-imide)s derived from N,N′-(pyromellitoyl) bis-L-tyrosine and various diamines

Five new optically active poly(amide-imide)s(PAIs) 5a–e were prepared by direct polycondensation reaction of N,N′- (pyromellitoyl) bis-L-tyrosine 3 as chiral dicarboxylic acid with various aromatic diamines 4a–e. Triphenylphosphite(TPP)/pyridine(py) in the presence of calcium chloride (CaCl2) and N-methyl-2-pyrrolidone (NMP) were successfully applied to direct polycondensation reaction. The resulting new polymers were obtained in good yields with inherent viscosities ranging between 0.48 dL/g and 0.6 dL/g. They were analyzed with a C.H.N. elemental analyzer, FTIR, 1H-NMR, UV-VIS spectroscopy and polarimeter (specific rotation measurement, [α] 25D ). Thermogravimetric analysis (TGA) indicated that the residual weight percentage of polymers at 600 °C were between 48.66 % and 64.21 %, which showed their thermal stability. These polymers are attractive to be used as packing materials in chromatography columns for separation of enantiomers.

Synthesis of porous spherical silicon oxynitride material and evaluation of its properties in reversed-phase chromatographic separation

Silica has been widely used as HPLC column packing material. However, the fact that base can attack the silanol and dissolve the silica embarrasses the utilization of silica stationary phase in high pH mobile phases (pH >8). In our previous research, the use of porous spherical silicon oxynitride (sph-SiON) material from high temperature nitridation of silica microspheres as stationary phase for HPLC has been explored, and the sph-SiON is stable to alkaline mobile phases and demonstrates excellent separation of a variety of polar compounds in hydrophilic interaction liquid chromatography (HILIC) mode. Herein, the degree of nitridation was studied as a function of temperature of nitridation at 750-1 050 degrees C, yielding the silicon oxynitride with 0.40%-12.0% (mass fraction) nitrogen from elemental analysis. At the temperature of 1 050 degrees C, the nitrogen content increased from 12.0% to 24.5% with the nitridation time increasing from 20 h to 120 h. The sph-SiON is stable when disposed in different pH aqueous solutions for one week. The sph-SiON material can be modified to give hydrophobic surface through the reaction of surface Si-NHx with dimethyloctadecylchlorosilane. Elemental analysis and 13C cross-polarization magic-angle spinning (CP/MAS) NMR spectrum of C18-sph-SiON prove the integration of C18 alkyl groups attached onto the sph-SiON surface. The chromatographic evaluation of C18-sph-SiON in reversed-phase separation mode was performed with alkylbenzenes as hydrophobic probes. Three alkylbenzene compounds can be separated and retained well on C18-sph-SiON even in the mobile phase of methanol/H2O (70/30, v/v) with 78 507 plates/m, and an excellent tailing factor (0.95) can be obtained for ethylbenzene. In comparison with C18-SiO2, C18-sph-SiON shows distinct differences with respect to different classes of analytes, i. e. neutral analyte naphthalene, acidic analyte ibuprofen, and basic analyte amitriptyline.

Polyfunctional low-capacity cation-exchange packing material for the separation of underivatized amino acids

A polyfunctional low-capacity cation-exchange column-packing material was developed for the simultaneous separation and determination of underivatized 20 amino acids including 16 proteinogenic ones using a binary gradient HPLC. The new packing material was prepared by sulfoacylating a highly crosslinked macroreticular poly(styrene-divinylbenzene) copolymer of 3μm in diameter commercially available for size-exclusion chromatography. The polyfunctionality could derive from unintentional carboxy groups innately present in the base polymers probably came from polymerization initiators in addition to the intentionally introduced sulfopropionyl groups, which was certified and evaluated by measuring dynamic capacity curves of the cation exchanger. Sixteen underivatized proteinogenic amino acids were separated in 23min using a binary high-pressure gradient elution system with two liquids of 1mmolL−1 H3PO4 and 20mmolL−1 NaH2PO4/30% (v/v) CH3CN, which led to the cycle time of 25min. In the case of separation of 20 amino acids, the cycle time was 27min. The developed low-capacity cation-exchange chromatography with post-column fluorescence detection was sufficiently quantitative, providing linear calibration lines ranged through almost three digit for all analytes. The detection limits were calculated as nmolL−1 order of magnitude with 20-μL injection. The method was applicable to the direct analysis of urinary amino acids of diagnostic markers for inborn errors of metabolism.

PEMBUATAN ETANOL FUEL GRADE DALAM KOLOM UNGGUN TETAP DENGAN ADSORBENT HYBRID ACTIVE GRANULATED ZEOLITE – SILIKA GEL

<p><strong><em>Abstract : </em></strong><em>Petroleum reserves in the world are dwindling, leading to efforts to obtain renewable energy sources.</em><em> </em><em>Prospects of development of bioethanol industry in Indonesia is quite interesting, because Indonesia has a variety of natural resources that can be processed into bioethanol.</em><em> </em><em>Drying technology is currently used to produce ethanol fuel such as membranes, Pressure Swing Adsorption and vapor phase adsorption.</em><em> </em><em>Adsorption is a method that is simple and relatively inexpensive.</em><em> </em><em>This research aims at studying the characteristics of ethanol adsorption capacity by a mixture of zeolite and silica gel to the acquisition of ethanol concentration.</em><em> </em><em>The process of vapor phase adsorption of ethanol occurs in fixed bed column using a feed with a concentration of 93-95% ethanol. Ethanol fermentation first purified using a distillation process in the column packing material to get the concentration.</em><em> </em><em>Ethanol liquid feed is vaporized in the tank.</em><em> </em><em>Ethanol vapor then flowed into the fixed bed column containing a mixture of active zeolite and silica. Water vapor adsorbed by the adsorbent in the column stack of this bed.</em><em> </em><em>Ethanol vapor that not adsorbed is then condensed.</em><em> Liquid ethanol results of the condensation process </em><em>is fuel grade ethanol.</em><em> </em><em>The variables studied were weight ratio of zeolite-silica gel (g) (75:25; 50:50, and 25:75) and type in a structured or random piles.</em><em> </em><em>Sampling for analysis of ethanol levels done every 5 minutes for 30 minutes at a temperature of 12 </em><em>°</em><em> C.</em><em> </em><em>The analysis was done by measuring the density of the solution condensation of the output of the column adsorber.</em><em> </em><em>In this research, obtained the highest ethanol content for this type of pile structured weight ratio zeolite: silica gel (g) respectively 75:25; 50:50, and 25:75 is the 99.2313% 99.5816%, and 99,</em><em> </em><em>9582%.</em><em> </em><em>In a random pile of ethanol content obtained by 99.6363%, 98.3215% and 99.881%.</em><em> </em><em>The maximum ethanol content obtained on zeolite-silica gel ratio 25:75 for both structured and random mix.</em><em> This is because the ratio of Si/Al-silica gel is greater than the zeolite thus more effective in the adsorption of ethanol. And derived ethanol content in the stack is more stable than the unstructured random. </em></p><p><em> </em><strong><em>Keywords: </em></strong><em>Adsorption, Zeolite Silica, Ethanol fuel grade</em></p><p> </p>

Calcium isotope fractionation in liquid chromatography with crown ether resins

Breakthrough mode liquid chromatography was employed to study calcium isotope fractionation. Highly porous silica beads, the inner pores of which were embedded with a benzo-18-crown-6 ether resin or a benzo-15-crown-5 ether resin, were used as column packing material. For both the resins, enrichment of heavier isotopes of calcium was observed in the frontal part of their respective calcium chromatograms. The values of the isotope fractionation coefficient were on the order of 10−3 and 10−4 for the benzo-18-crown-6 ether and benzo-15-crown-5 ether resins, respectively. The observed isotope fractionation coefficient was dependent on the concentration of hydrochloric acid in the calcium feed solution; a higher hydrochloric acid concentration resulted in a smaller fractionation coefficient value. The present calcium isotope effects were most probably mass dependent, indicating they came from isotope effects based on molecular vibration. Molecular orbital calculations supported the present experimental results in a qualitative fashion.