Separation of magnesium isotopes by a 2'-aminomethyl-18-crown-6 bonded Merrifield peptide resin

Separation of magnesium isotopes was investigated by chemical ion exchangewith synthesized 2'-aminomethyl-18-crown-6 (AM18C6) bonded Merrifieldpeptide resin using an elution chromatographic technique. The capacity ofthe novel crown ion exchanger was found to be 2.3 meq/g dry resin. The heavierisotopes of magnesium were enriched in the solution phase, while the lighterisotopes were enriched in the resin phase. The single stage separation factorwas determined according to the method of GLUECKAUF from the elution curveand isotopic assays. The separation factors of ²⁴Mg–²⁵ Mg, ²⁵ Mg–²⁶ Mg, and ²⁴ Mg–²⁶ Mg isotope pair fractionations were 1.012, 1.005, and 1.022, respectively.     

Separation of lithium isotopes by NDOE bonded Merrifield peptide resin

The novel NDOE (1,12,15-triaza-3,4:9,10-dibenzo-5,8-dioxacycloheptadecane) ion exchange resin was prepared. The ion exchange capacity of NDOE azacrown ion exchanger was 0.2 meq/g dry resin. A study on the separation of lithium isotopes was carried out with NDOE novel azacrown ion exchange resin. The lighter isotope,⁶Li concentrated in the solution phase, while the heavier isotope,⁷Li is enriched in the resin phase. By column chromatography (0.1 cm I.D.×32 cm height) using 2.0M NH₄Cl as an eluent, a separation factor,a=1.0201 was obtained.     

Separation of lithium isotopes by NTOE-bonded Merrifield peptide resin

A study of the elution chromatographic separation of lithium isotopes was carried out with NTOE-bonded Merrifield peptide resin. This resin had a capacity of 0.29 meq/g dry resin. Upon column chromatography [0.2 cm(I.D)×32 cm (height)] using 1.0M NH₄Cl solution as an eluent, a single separation factor of 1.026 was obtained by the Glueckauf theory. The heavier isotope, ⁷Li was concentrated in the resin phase, while the lighter isotope, ⁶Li was enriched in the solution phase.     

Chromatographic separation of magnesium isotopes by monoazacrown bonded Merrifield peptide resins

Magnesium isotope separation was investigated by chemical ion exchange with the 1-aza-12-crown-4 (I) and the 1-aza-18-crown-6 (II) bonded Merrifield peptide resin using an elution chromatographic technique. The capacities of each novel monoazacrown ion exchanger were 1.0 meq/g for (I) and 2.3 meq/g for (II) bonded Merrifield peptide resins, respectively. The single stage separation factor was determined according to the method of Glueckauf from the elution curves and isotopic assays. The separation factors of magnesium isotope pairs, ²⁴Mg²⁺–²⁵Mg²⁺, ²⁴Mg²⁺–²⁶Mg²⁺ and ²⁵Mg²⁺–²⁶Mg²⁺ were 1.015, 1.029, and 1.014 for (I) and 1.012, 1.024, and 1.009 for (II) bonded Merrifield peptide resins, respectively.     

Separation of lithium isotopes by elution chromatography with an AB18C6 bonded Merrifield peptide resin

Cation exchange chromatographic separation of lithium isotopes was carried out with an 4'-aminobenzo-18-crown-6(AB18C6) bonded Merrifield peptide resin. This resin has a capacity of 2.25 meq/g dry resin. Upon column elution chromatography, a single stage separation factor of 1.0095, was obtained by the Glueckauf theory from the elution curve and isotopic assays. The heavier isotope, ⁷Li, was concentrated in the resin phase, while the lighter one, ⁶Li, concentrated in the solution phase.     

Separation of lithium isotope by NTOE compound

In recent years chances of using rhenium-186 and rhenium-188 as radioactive isotopes in diagnostic and therapeutic applications are increased very much due to the characteristic radiochemical and chemical properties of these two radioisotopes. In particular, chemical similarities between⁹⁹Tc and^99mTc pair and¹⁸⁶Re and¹⁸⁸Re pair make it easier to correlate the two groups of compounds. Rhenium-188 is generated from the beta-decay of tungsten-188 which was produced by double neutron capture on enriched tungsten-186 oxide. It is of great interest to examine the impurities in the eluate by radiochemical neutron activation. For this purpose, the preconcentration of the impurities in samples were necessary, and it was achieved by adsorption on hydrated magnesium oxide.     

Separation of lithium isotopes with the N3O2 trimerrifield peptide resin

A study on the separation of lithium isotopes was carried out with 1,13-dioxa-4,7,10-triazacyclopentadecane-4,7,10-trimerrifield peptide resin [N₃O₂3M]. The resin having N₃O₂ as an anchor group has a capacity of 0.2 meq/g dry resin. Upon column chromatography [0.1 cm (I.D)×30 cm (height)] using 1.0M NH₄Cl solution as an eluent, a single separation factor of 1.00104 was obtained from the elution curve and isotope ratios based on theGlueckauf theory. The heavier isotope,⁷Li concentrated in the resin phase, while the lighter isotope,⁶Li enriched in the solution phase.     

Adsorption and isotope effects by ion exchange with aqueous-2-aminomethyl-18-crown-6 bonded merrifield resin

Magnesium isotopes effects were investigated by chemical ion exchange using synthesized 2-aminomethyl-18-crown-6 (AM18C6) bonded Merrifield peptide resin. It was found that separation factors larger those reported previously were obtained, and the hydration and isotope mass effects are more significant than that of the complexation. The capacity of the crown ion exchanger was 2.3 meq/g dry resin. The adsorption capacity of the resin for magnesium ion was 26.8 mg/g dry resin at pH 7. The heavier isotopes of magnesium were enriched in the solution phase, while the lighter isotopes were enriched in the resin phase. The separation factors of (24)Mg-(25)Mg, (24)Mg-(26)Mg, and (25)Mg-(26)Mg were 1.0085, 1.0162, and 1.0081, respectively.     

Enrichment of lithium isotopes by a triazacrown trimerrifield peptide resin

A study on the elution chromatographic separation of lithium isotopes was carried out with a triazacrown trimerrifield peptide resin. The capacity of the triazacrown trimerrifield peptide resin has a value of 0.08 meq/g. Upon column chromatography [0.2 cm (I.D)×35 cm (height)] using 4.0M NH₄Cl solution as an eluent, the single stage separation factor of 1.028 was obtained by the Glueckauf theory. The heavier isotope, ⁷Li, was concentrated in the resin phase, while the lighter isotope, ⁶Li, was enriched in the solution phase.     

Separation of lithium isotope by azacrown tetramerrifield peptide resin

A study on the separation of lithium isotope was carried out with N₄O azacrown ion exchange resin. The lighter⁶Li isotope concentrated in the solution phase, while the heavier⁷Li isotope is enriched in the resin phase. Upon column chromatography (0.3 cm I.D.×15.5cm height) using 0.5M NH₄Cl as an eluent, single separation factor, α=1.00127 was obtained.     

Separation of magnesium isotopes by chemical exchange with a polymer-bound azacrown compound

The chromatographic separation of magnesium isotopes was investigated by chemical exchange with the recently synthesized 1-oxa-4,7,10,13-tetraazacyclopentadecane-4,7,10,13-tetramerrifield peptide resin [N₄O·4M]. The capacity of the novel N₄O-4 Merrifield ion exchanger was 1.0 meq/g dry resin. The heavier isotope²⁶Mg concentrated in the resin phase, while the lighter isotopes²⁴Mg, and²⁵Mg are enriched in the fluid phase. The maximum separation factors , for²⁵Mg–²⁶Mg and²⁴Mg–²⁶Mg were found to be 1.048 and 1.022, respectively, at 20.0±0.02 °C with 2.0 M ammonium chloride solution as an eluent.     

Separation of magnesium isotopes by N4S2 azacrown ion exchanger

The chromatographic separation of magnesium isotopes was investigated by chemical ion exchange with 1,16-dithia-4,7,10,13-tetraazacyclooctadecane-4,7,10,13-tetramerrifield peptide resin[N₄S₂·4M] synthesized recently. The capacity of novel N₄S₂ azacrown ion exchanger was 0.34 meq/g dry resin. The heavier isotopes of magnesium concentrated in the resin phase, while the lighter isotopes are enriched in the solution phase. The glass ion exchange column used was 30 cm long with inner diameter of 0.2 cm, and the 1.0M NH₄Cl solution was used as an eluent. The separation factors of²⁴Mg−²⁵Mg,²⁵Mg−²⁶Mg, and²⁴Mg−²⁶Mg were 1.047, 1007, and 1.008, respectively.     

Separation of lithium and magnesium isotopes by hydrous manganese(IV) oxide

Lithium and magnesium isotopes were separated by chemical ion exchange using hydrous manganese(IV) oxide and elution chromatography. The capacity of manganese(IV) oxide was 0.5 meq/g. The glass ion exchange column used was 35 cm long with an inner diameter of 0.2 cm, and 2.0M CH₃COONH₄ solution served as eluent. The single stage separation factor was determined from the elution curves and isotopic assays according to the method of Glueckauf. The separation factor of ⁶Li⁺-⁷Li⁺ was 1.022±0.002, those of ²⁴Mg²⁺-²⁵Mg²⁺, ²⁴Mg²⁺-²⁶Mg²⁺, and ²⁵Mg²⁺-²⁶Mg²⁺ were 1.012±0.001, 1.021±0.002, and 1.011±0.001, respectively.     

Separation of vanadium isotopes by ion-exchange chromatography

Cation-exchange displacement chromatography of VO2+ was carried out for studying vanadium isotope effects in carboxylate ligand-exchange systems. The heavier isotope 51V was enriched in the carboxylate complex solution. The isotope separation coefficients epsilon(= alpha-1) for 50V/51V were 2.2 x 10(-4) and 2.4 x 10(-4) for citrate and lactate systems at 298 K, respectively. These values are much larger than those obtained in a previous study on the malate system. The existence of binuclear complexes of VO2+ may create the conditions for larger isotope fractionation. From the viewpoint of the process development of isotope separation, the heights equivalent to a theoretical plate of these processes were analyzed and found to be very small in each system due to the homogeneous, small and highly porous resin used. Citrate may be better than the other tested systems for the vanadium isotope separation.     

Adsorption and isotope effects by ion exchange with 1-aza-12-crown-4 bonded Merrifield peptide resin

Magnesium isotope effects were investigated by chemical ion exchange with synthesized 1-aza-12-crown-4 bonded Merrifield peptide resin using elution chromatography. The capacity of azacrown ion exchanger was 0.89 meq/g dry resin. The heavier isotopes of magnesium were enriched in the resin phase, while the lighter isotopes were enriched in the solution phase. The hydration effect is less than the complexation and isotope mass effects. The single stage separation factor was determined according to the method of Glueckauf from the elution curve and isotopic assays. The separation factors of 24Mg(2+)-25Mg(2+), 24Mg(2+)-26Mg(2+), and 25Mg(2+)-26Mg(2+) were 1.012, 1.023, and 1.011, respectively.     

Boc和Fmoc保护氨基酸与M树脂和王氏树脂结合率的比较

M树脂与Boc保护的亮氨酸、甘氨酸或苯丙氨酸的铯盐成酯反应摩尔比1:1.2,时间31h,其产物用重量法和水杨醛法测得的结合率均值分别为87.3%、89.1%和89.6%。王氏树脂与Fmoc保护的亮氨酸、甘氨酸或苯丙氨酸反应48h,树脂:Fmoc氨基酸:DCC:DMAP摩尔比为1:3:4:1,其产物结合率的均值分别为44.2%、30.4%和56.2%。结果表明,前者产物结合率高于后者。另外,重量法与水杨醛法测得的结合率相差不超过2.7%,但重量法更方便,易行。     

阴离子交换树脂提取谷氨酸

谷氨酸是蛋白质的主要构成成分,具有重要的生理生化功能,其主要应用于食品、医药等工业。目前国内从发酵液中提取谷氨酸普遍采用的步骤是:先用等电法结晶大部分谷氨酸,等电母液采用离子交换法浓缩其中的谷氨酸,此时谷氨酸为阳离子,洗脱高浓度馏分再回入等电罐进行结晶回收[1]。上述工艺的最大缺点是:在结晶和离子交换过程中要使用大量的硫酸调节发酵液和母液的pH,造成环境污染;且提取谷氨酸后产生的废液中其COD和SO2 4和氨态氮含量很高,用常规的方法较难处理[2]。由于谷氨酸发酵液的pH为6 8～7 2,此时,谷氨酸主要以阴离子状态形式存…     

Separation of multiphosphorylated peptide isomers by CZE

A separation of mono, doubly and triply phosphorylated isomers was developed with CZE with an aqueous electrolyte containing 3.9 mol/L formic acid and 30% v/v trifluoroethanol. Thus a mixture of ten phosphopeptides corresponding to the human tau sequence 226-240 was separated within 70 min. Although peptides with different phosphorylation degrees, i.e. 0-3 phosphate groups, were well separated, some of the phosphopeptide isomers containing one or two phosphate groups were only partially separated. The electrolyte system is compatible with both MALDI- and ESI-MS, allowing a direct coupling, and thus could have some interesting applications in proteomics.