离子色谱法分析金属离子的研究进展

综述了离子色谱法(IC)分析金属离子的研究进展,对目前应用于分析金属离子的阳离子交换IC、阴离子交换IC和螯合离子色谱进行了评述。阳离子交换IC是IC分析金属离子的主要形式,固定相为强酸(磺酸)型阳离子交换剂和弱酸(羧酸)型阳离子交换剂,结合适当的检测方法,阳离子交换IC可以测定碱金属、碱土金属、过渡金属、稀土离子、铵离子及低相对分子质量的有机胺类分子等。阴离子交换IC可以分析碱土金属、过渡金属、稀土离子等,对金属离子的分析具有更好的选择性,并可以实现金属离子和无机阴离子的同时测定。螯合离子色谱可以对复杂基体中的痕量金属离子进行测定。引用文献125篇。     

Mass spectrometric study of some protonated and lithiated 2,5-disubstituted-1,3,4-oxadiazoles

The mass spectrometric behavior of lithiated derivatives of 2,5-disubstituted-1,3,4-oxadiazoles has confirmed the skeletal rearrangement presented earlier for protonated derivatives. In the case of [M + H](+) ions the loss of isocyanic acid was observed and for [M + Li](+) ions the loss of lithium isocyanate occurred. On the other hand, benzoyl ions [RCO](+) were formed from [M + H](+) ions, but not from [M + Li](+) ions. Formation of benzoyl ions was in agreement with the differences between bond orders calculated for [M + H](+) ions and neutral molecules. From [M + Li](+) ions the [RCNLi](+) fragment ions were formed, but the formation of [RCNH](+) fragment ions from [M + H](+) ions was not observed. This result can be explained on the basis of theoretically calculated stabilities of these fragment ions, since the calculated heats of formation of [RCNLi](+) ions were found to be substantially lower than those of the respective [RCNH](+) ions.     

Soft-sputtering of insulin films in argon-cluster secondary ion mass spectrometry

In secondary ion mass spectrometry (SIMS) of organic substances, the dissociation of the sample molecules is crucial. We have developed SIMS equipment capable of bombardment, where the primary ions are argon cluster ions with kinetic energy per atom controllable down to 1 eV. We previously reported the detection of intact ions of insulin and cytochrome C using this equipment. In this paper, we present a detailed characterization of the emission of secondary ions from insulin, focusing on the difference in secondary ion yield between intact ions and fragment ions by varying the incident angle of the cluster ions. The emission intensity of the intact ions was changed drastically due to the exposed dosage and incident angle of the cluster ions in contrast to the fragment ions. We discuss these results based on the manner in which the argon-cluster ions collide with the organic solid.     

Erratic ions: self-assembly and coassembly of ions of nanometer size and of irregular structure

The solution behavior of some ions resembles that of surfactants. The aim of this review is to contextualize the behavior of ions with uneven structure and/or hydration shell, such as nanoions, intrinsically amphiphilic ions, and ions with irregular chemical composition. Hints regarding ionspecificity and other peculiar features of less conventional ions are discussed. Such ions can exhibit ion pairing and like-charge self-assembly, thus resembling amphiphilic molecules. Irregular ions and nanoions are in some cases surface active that reminds classical surfactants. Coassembly of several ions with synthetic polymers and proteins cannot be described by simple salting-in and host–guest models pointing to the approach, in which ions are not used as solutes but as building nanoblocks.     

Gas-phase peptide/protein cationizing agent switching via ion/ion reactions

Polypeptide ions comprising different cationizing agents show distinct fragmentation behavior in the gas phase. Thus, it is desirable to be able to form ions with different cationizing agents such as protons and metal ions. Usually, metal-cationized peptide/protein ions are introduced to the mass spectrometer by electrospraying solutions containing a mixture of the peptide/protein of interest and a metal salt. A new technique for generating metal-containing polypeptide ions that involves gas-phase ion/ion reactions is described. In this strategy, solutions of metal-containing ions and solutions of proteins are each electrosprayed into separate ion sources. The approach allows for independent maximization of ion signal and selection of ions prior to gas-phase reactions. Selected ions are stored in a quadrupole ion trap where reactions of ions of opposite polarity form metal-cationized peptides and proteins in the gas phase by cation switching. This approach affords a high degree of flexibility in forming metal-containing peptide and protein ions via the ability to mass-select reactant ions. The ability to form a variety of peptide/protein ions with various cationizing reagents in the gas phase is attractive both for the study of intrinsic interactions of metal ions with polypeptides and for maximizing the structural information available from tandem mass spectrometry of peptides and proteins.     

Electrodialytic transport properties of cation exchange membranes in the presence of cyclodextrins

After commercial cation exchange membranes (NEOSEPTA) had been immersed in an aqueous cyclodextrin solutions, electrodialysis of a 1:1 mixed solutions of alkaline earth metal ions and sodium chloride was carried out in the presence of cyclodextrins in the desalting side solution. Adsorption of the cyclodextrins in the membrane matrix was confirmed by IR spectrum, X-ray photoelectron spectroscopy (XPS) and the weight increase of each corresponding component of the membranes. As a result of adsorption of the cyclodextrins in the membranes, transport numbers of alkaline earth metal ions relative to sodium ions decreased compared with those of the membranes without cyclodextrins. Water content in the membrane increased and a ratio of calcium ions (alkaline earth metal ions) to sodium ions in the membrane phase decreased after adsorption of the cyclodextrins. This is due to existence of the compounds having hydrophilic outer surface, cyclodextrins, in the membrane matrix. The decrease in the transport number of calcium ions relative to sodium ions was due to both decrease in a ratio of mobility of calcium ions to that of sodium ions and decrease in an ionic ratio of calcium ions to sodium ions in the membrane phase.     

13C labelling study of the interconversion of ethylbenzene, 7-methylcycloheptatriene and p-xylene ions

The isomerization of the molecular ions of ethylbenzene, 7-methylcycloheptatriene and p-xylene by skeletal rearrangement prior to the formation of [C₇H₇]⁺ ions has been investigated by using ¹³C labelled compounds. The results obtained for ions generated by 70 eV and 12 eV electron impact, and fragmenting in the ion source, the 1st field free region and the 2nd field free region, respectively, are compared with those obtained from D labelled derivatives. It is shown that at long reaction times metastable p-xylene ions lose a methyl radical after scrambling of all C atoms and H atoms, while the unstable molecular ions in the ion source react by specific loss of one of the methyl substituents. Both unstable and metastable ethylbenzene ions fragment by two competing mechanisms, one corresponding to specific loss of the terminal methyl group, and the other involving scrambling of all C and H atoms. These results are discussed by use of a dynamic model developed for the mutual interconversion and fragmentation of the molecular ions of ethylbenzene, methylcyclo-heptatriene and p-xylene. The experimental results can be explained by an equilibrium between metastable methylcycloheptatriene ions and p-xylene ions with sufficient energy for skeletal rearrangement, while about 40% of the metastable ethylbenzene ions fragment after rearrangement to methylcycloheptatriene ions and about 60% of the ethylbenzene ions rearrange further to xylene ions before fragmentation. Metastable methylcycloheptatriene ions, mainly lose a methyl group without a skeletal rearrangement, however, because the rearranged ions are kinetically trapped as ‘stable’ xylene ions or ethylbenzene ions.     

Electron impact mass spectral fragmentation patterns of 2a,4-disubstituted 5-benzoyl-2-chloro-2a,3,4,5-tetrahydroazeto[1,2-a][1,5]benzodiazepin-1( 2H)-ones

The mass spectrometric behaviour of six 2a,4-disubstituted 5-benzoyl-2-chloro-2a,3,4,5-tetrahydroazeto[1,2-a][1,5]benzodia zepin-1(2H)-ones has been studied with the aid of mass-analysed ion kinetic energy spectrometry and accurate mass measurements under electron impact ionization. All compounds show a tendency to eliminate a chlorine atom, a chlorine atom plus benzaldehyde, benzoyl radical, chloroketene or chlorine atom plus CO and H2O molecules to yield, respectively, [M-Cl]+ ions, 2a,4-disubstituted 2a,3-dihydroazeto[1,2-a][1,5]benzodiazepin-1(2H)-one ions, [M-PhCO]+ ions, 2,4-disubstituted 1-benzoyl-2,3-dihydro-1H-1,5-benzodiazepine ions, or 1,2,4-trisubstituted 1H-1,7-benzodiazonine ions, which could also be formed from [M-Cl]+ ions by loss of CO and H2O molecules simultaneously. The [M-Cl]+ ions could further lose benzoyl radical to form [M-Cl-PhCO]+ ions, or lose benzoyl amide and undergo a rearrangement to form 4,6-disubstituted 1-benzoazocine-2(1H)-one ions. The [M-PhCO]+ ions could eliminate NH to produce 2a,4-disubstituted 2,2a,3,4-tetrahydroazeto[1,2,-a]quinolin-1-one ions, which could further eliminate chloroketene, CO and/or HCl to produce some important ions, respectively. 2,4-Disubstituted 1-benzoyl-2,3-dihydro-1H-1,5-benzodiazepine ions could lose benzoyl radical to yield 2,4-disubstituted 2,3-dihydro-1H-1,5-benzodiazepine ions, which could further yield other small fragment ions by loss of propene/styrene or small fragments.     

Decationization and dealumination of clinoptilolite tuff and ammonium exchange on acid-modified tuff

The paper presents results of investigation of exchange of the clinoptilolite tuff cations with hydrogen ions from HCl solution of concentration 0.1 mmol cm(-3) and ammonium ions solutions of concentrations 0.0071 to 2.6 mmol cm(-3). Molal concentrations, x (mmol g(-1)) of cations exchanged in acid solution and in ammonium ions solutions were compared with molal concentrations of cations obtained by determination of the cation-exchange capacity of clinoptilolite tuff. The obtained results show that at ammonium ion concentrations lower than 0.1 mmol cm(-3), with regard to exchange capacity for particular ions, best exchanged are Na+ ions, followed by Mg2+ and Ca2+ ions, while exchange of K+ ions is the poorest (Na+ > Mg2+ > Ca2+ > K+). At ammonium concentrations from 0.2 to 1 mmol cm(-3) the order is Na+ > Ca2+ > Mg2+ > K+. At concentrations higher than 1 mmol cm(-3) the order is Na+ > Ca2+ > K+ > Mg2+. The results are a consequence of the uptake of hydrogen ions by zeolite samples in ammonium ions solutions at concentrations lower than 1 mmol cm(-3) and indicate the importance of Mg2+ (besides Na+ ions) for the exchange between clinoptilolite cations and H+ ions, in contrast to K+ ions, whose participation in the reaction with H+ ions is the lowest. During decationization of the clinoptilolite in acid solution, best exchanged are Na+, Mg2+, and Ca2+ ions, while exchange of K+ ions is the poorest. Due to poor exchange of K+ and H+ ions and good exchange of Na+, Mg2+, and Ca2+ ions, it is to be assumed that preservation of stability of the clinoptilolite structure is caused by K+ ions present in the channel C. Clinoptilolite is dissolved in the clinoptilolite A and B channels where Na+, Mg2+, and Ca2+ ions are present. On the acid-modified clinoptilolite samples, exchange of ammonium ions is poorer than on natural zeolite. The longer the contact time of the zeolite and acid solution, the worse ammonium ions exchange. It can be assumed that H+ ions exchanged with zeolite cations are consumed for solution of aluminum in the clinoptilolite structure; therefore the concentration of H+ ions as exchangeable cations decreases. In the ammonium ion solution at a concentration of 0.0065 mmol cm(-3), from the acid-modified zeolite samples, Al3+ ions are exchanged best, followed by Na+, Mg2+, Ca2+, and K+ ions. Further to the results, it is to be assumed that exchangeable Al3+ ions available from clinoptilolite dissolution are best exchanged with H+ ions in acid solution.     

Peptide sequence scrambling through cyclization of b5 ions

The CID mass spectra of the MH(+) ions and the b(5) ions derived therefrom have been determined for the hexapeptides YAAAAA, AYAAAA, AAYAAA, AAAYAA, and AAAAYA. The CID mass spectra for the b(5) ions derived from the five isomers are essentially identical and show abundant ion signals for nonsequence b ions. This result is consistent with cyclization of the b(5) ions to a cyclic pentapeptide before fragmentation; this cyclic peptide can open at various positions, leading to losses of amino acid residues that are not characteristic of the original amino acid sequence. These nonsequence b ions are also observed in the fragmentation of the MH(+) ions and increase substantially in importance with increasing collision energy. A comparison of the fragmentation of AAAYAA and Ac-AAAYAA indicates that N-acetylation eliminates the cyclization of b(5) ions and, thus, eliminates the nonsequence ions in the CID mass spectra of both b(5) and MH(+) ions.     

海藻酸钠与钙或锌离子凝胶动力学过程研究

测定了海藻酸钠与锌或钙离子交联的凝胶动力学过程，利用线性模型(LAM)对凝胶过程进行了模拟．实验结果表明，钙或锌离子的初始反应速率方程分别为：dCCa/d(t)[mol^-1s^-1]=0.000109C^0.796与dCZn/d(t)[mol^-1s^-1]=0.0000405C^0.317；利用线性模型(LAM)可较好的拟合凝胶全过程；LAM模型计算结果表明，随凝胶离子浓度增加，凝胶离子表观扩散系数增加，凝胶速率加快，完全凝胶时间缩短：在相似的凝胶离子浓度下，钙离子的表观扩散系数大于锌离子的表观扩散系数，表明海藻酸锌完全凝胶时间较长，这与实际凝胶过程相符，主要是锌离子凝胶体系的刚性较强及锌离子半径相对较大造成的。     

Halogeno-substituted 2-aminobenzoic acid derivatives for negative ion fragmentation studies of N-linked carbohydrates

Negative ion electrospray mass spectra of high-mannose N-linked glycans derivatised with 2-aminobenzoic acids and ionised from solutions containing ammonium hydroxide gave prominent [M-H](-) ions accompanied by weaker [M-2H](2-) ions. Fragmentation of both types of ions gave prominent singly charged glycosidic cleavage ions containing the derivatised reducing terminus and ions from the non-reducing terminus that appeared to be products of cross-ring cleavages. Differentiation of these two groups of ions was conveniently achieved in a single spectrum by use of chloro- or bromo-substituted benzoic acids in order to label ions containing the derivative with an atom with a distinctive isotope pattern. Fragmentation of the doubly charged ions gave more abundant fragments, both singly and doubly charged, than did fragmentation of the singly charged ions, but information of chain branching was masked by the appearance of prominent ions produced by internal cleavages.     

Electron impact mass spectral fragmentation of 2a,4-disubstituted 2-chloro/2,2-dichloro-2,2a,3,4-tetrahydro-1H-azeto[2,1-d][1,5]benzothia zepin-1-ones

The mass spectrometric behaviour of nine 2a,4-disubstituted 2-chloro/2,2-dichloro-2,2a,3,4-tetrahydro-1H-azeto[2,1-d][1,5]b enzothiazepin-1-ones has been studied with the aid of mass-analysed ion kinetic energy spectrometry and accurate mass measurements under electron impact ionization. All compounds show a tendency to eliminate a neutral chlorine atom, or a chloroketene, or neutral propene, or styrene or substituted styrene molecule, plus Cl and/or H (or Cl) atom(s), to yield [M-Cl]+ ions, 2,3-dihydro-1,5-benzothiazepine derivative ions, 4,5-dihydro-5H-1,5-benzothiazepin-4-one ions which can further lose CO to give 1,4-benzothiazine ions. Both molecular ions and [M-Cl]+ ions show a tendency to eliminate an ethyl or benzyl/substituted benzyl radical to produce 2,2a-dihydro-1H-azeto[2,1-c][1,4]benzothiazin-1-one ions. The [M-Cl]+ ions could undergo rearrangement to yield 2,2a-dihydro-1H-azeto[2,1-d][1,5]benzothiazepin-1-one ions, 2,2a,3,4-tetrahydro-1H-azeto[1,2-a]quinoline ions or 1,1a,2,3-tetrahydro-azirino[2,1-d][1,5]benzothiazepine ions by loss of an ethane or a benzene/substituted benzene, a SH radical or a CO molecule. The molecular ions could also undergo rearrangement reactions to form other small fragment ions.     

Surface dependent hydrogen rearrangement reactions in field ionisation mass spectrometry

Surface dependent hydrogen rearrangement reactions under field ionisation conditions have been investigated. It was not possible to detect surface-induced intramolecular hydrogen rearrangements in molecular ions, in accordance with theoretical expectations. The possibility of intramolecular hydrogen rearrangements exists only for radical ions chemically bound to the emitter surface, for example, the [M – H]⁺ ions of the alcohols. The great majority of surfacedependent hydrogen transfer reactions are intermolecular reactions between parts of different molecules or ions bound to the emitter surface. These reactions produce fragment ions, cluster ions and doubly charged ions.     

Dissociative electron attachment to glycyl-glycine, glycyl-alanine and alanyl-alanine

The processes of negative ions formation of dipeptides glycyl-glycine, glycyl-alanine and alanyl-alanine in the conditions of resonant electron capture have been studied with a help of negative ions mass spectrometry. Using a thermochemical approach, the main channels of fragment negative ions formation were found and the structure of the ions were established. The isobaric ions have been identified by the experiments with high mass resolution. The cross sections of fragment ions formation were measured. The metastable fragmentation of [M-H](-) and [M-COOH](-) ions in the energy range 4.5-7.5 eV have been found.     

Study of Host-Guest Complexation of Alkaline Earth Metal Ion,Aluminum Ion and Transition Metal Ions with Crown Ethers by Fast Atom Bombardment Mass Spectrometry

Complexations of crown ethers with alkali metal ions have been investigated extensively by FAB mass spectrometry over the past decade, but very little attention has been paid to reactions of crown ethers with other classes of metal ions such as alkaline earth metal ions, transition metal ions and aluminum ions. Although fast atom bombardment ionization mass spectrometry has proven to be a rapid and convenient method to determine the binding interactions of crown ethers with metal ions, problems in reliabilities for quantitative measurements of” binding strength for the host-guest complexes have been described in the literature. Thus, in this paper, applications of FAB/MS for investigating the complexation of crown ethers with various classes of metal ions is discussed. Extensive fragmentations for neutral losses such as C₂H₄O or C₂H₄ molecules from the host-guest complexes could be observed. The reason is attributed to the energetic bombardment processes of FAB occuring in the formation of these complexes. Complexes of cyclen with metal ions also show neutral losses of C₂H₄NH molecules leading to fragment ions. Transition metal ions usually form (Crown + MCl)⁺ type of ions, alkaline earth metal ions can form both (Crown + MCl)⁺ and (Crown + MOH)⁺ type of ions. But for aluminum ions, only (Crown + Al(OH)₂)⁺ type of ions could he observed.     

气相中卤代苯离子-分子反应产物的串联质谱研究

应用碰撞诱导解离技术研究了氯代苯、溴代苯和碘代苯离子-分子反应产物的碎裂反应特性,与联苯的分子离子和质子化溴代联苯的碰撞诱导解离谱比较获得了产物离子的结构信息.     

Comparison of infrared multiphoton dissociation and collision-induced dissociation of supercharged peptides in ion traps

The number and types of diagnostic ions obtained by infrared multiphoton dissociation (IRMPD) and collision-induced dissociation (CID) were evaluated for supercharged peptide ions created by electrospray ionization of solutions spiked with m-nitrobenzyl alcohol. IRMPD of supercharged peptide ions increased the sequence coverage compared with that obtained by CID for all charge states investigated. The number of diagnostic ions increased with the charge state for IRMPD; however, this trend was not consistent for CID because the supercharged ions did not always yield the greatest number of diagnostic ions. Significantly different fragmentation pathways were observed for the different charge states upon CID or IRMPD with the latter yielding far more immonium ions and often fewer uninformative ammonia, water, and phosphoric acid neutral losses. Pulsed-Q dissociation resulted in an increase in the number of internal product ions, a decrease in sequence-informative ions, and reduced overall ion abundances. The enhanced sequence coverage afforded by IRMPD of supercharged ions was demonstrated for a variety of model peptides, as well as for a tryptic digest of cytochrome c.     

Preparation and properties of anion exchange membranes having pyridinium or pyridinium derivatives as anion exchange groups

Anion exchange membranes with pyridinum groups and various pyridinium derivative groups were prepared from a copolymer membrane composed of chloromethylstyrene and divinylbenzene, and pyridine and pyridine derivatives. The anion exchange membranes obtained showed excellent electrochemical properties in electrodialysis. The transport numbers of sulfate ions, bromide ions, nitrate ions, and fluoride ions relative to chloride ions were evaluated in connection with the species of a substituent and the position of the substituent in the pyridinium groups. In general, when a hydrophilic substituent (methanol groups) existed at the 2-position of the pyridinium groups, nitrate ions and bromide ions, which are less hydrated, permeated through the membranes with difficulty, and sulfate ions permeated selectively through the membranes. On the other hand, when hydrophobic groups, for example, ethyl groups, existed at the 2-position of the pyridinium groups, bromide ions and nitrate ionspermeated selectively through the membranes and fluoride ions had difficulty permeating through the membranes. The carbon number of the alkyl chain of 4-alkyl pyridinium groups also affected permeation of nitrate ions and bromide ions due to the change in hydrophilicity of the membranes. Though the hydration of the anions and the species of the substituent at the 2-position of the pyridinium groups were related to selective permeation of the anion through the membranes, permeation of sulfate ions was not as sensitive to the hydrophilicity of the membranes. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 49–58, 1998     

Dynamics of Li+ ions in strontium metaphosphate glasses

Dynamics of Li+ ions in strontium metaphosphate glasses has been studied in the frequency range of 10 Hz-2 MHz and in the temperature range of 273-573 K. The dc conductivity increases and the activation energy decreases with the replacement of strontium ions by lithium ions in the glass compositions. The ac electrical data have been studied using the modulus and conductivity formalisms. We have observed that the stretching exponent decreases and the frequency exponent increases with the replacement of strontium ions by lithium ions in these glasses. The variation of these parameters was explained in terms of ion-ion interaction. The mobile ion concentration remains nearly constant, which indicates that the mobility of the migrating ions increases when the alkaline earth ions are replaced by the alkali ions.