共查询到20条相似文献,搜索用时 62 毫秒
1.
Kurt Aitzetmüller 《Journal of separation science》1993,16(8):488-490
The fatty acid composition of the seed lipids of plants, in contrast to leaf lipids, may contain highly specific unusual fatty acids, which are often correlated to plant family. For example, petroselinic acid is typical for the Apiacea family, cyclopropene fatty acids are typical for the Malvaceae family, and cyclopentene-ring containing fatty acids for the Flacourtiaceae family. Other fatty acids may be characteristic for certain sub-families or only for certain species of plants within a family or genus. γ-Linolenic acid, Δ5–18:3 and Δ5–20:3 fatty acids and others may occur in several plant families, but are still linked to certain related species only. They can be analyzed by high-resolution capillary GLC. Particularly interesting is the situation in the family Ranunculaceae. GLC fingerprints of fatty acids are shown that may indicate a closer or less close relationship between species within this family. 相似文献
2.
Summary An ion chromatographic (IC) method has been developed for the separation of alkylsulphonic acid. Two different stationary
phases, silica-based and polymer-based ion-exchange resins, were studied using pure ion exchange and/or hydrophobic interaction
mechanisms. Correlations between analyte hydrophobicity and eluent polarity were made in order to investigate the possibility
of changing the dominant separation mechanism by varying the eluent composition. The alkyl chain lengths of the sulphonic
acids analysed ranged from C1 to C9. Detection limits in the submicromolar range were obtained by suppressed conductivity detection. 相似文献
3.
Summary An ion chromatographic (IC) method has been developed for the separation of alkylsulphonic acid. Two different stationary
phases, silica-based and polymer-based ion-exchange resins, were studied using pure ion exchange and/or hydrophobic interaction
mechanisms. Correlations between analyte hydrophobicity and eluent polarity were made in order to investigate the possibility
of changing the dominant separation mechanism by varying the eluent composition. The alkyl chain lengths of the sulphonic
acids analysed ranged from C1 to C9. Detection limits in the submicromolar range were obtained by suppressed conductivity detection. 相似文献
4.
Selective determination of dithiocarbamate (DTC) fungicides is mainly performed by hydrophilic interaction liquid chromatography (HILIC). According to Crnogorac and Schwack, DTC analyses by HILIC only lead to meaningful results with a zwitterionic polymer-based hydrophilic interaction liquid chromatography (ZIC-pHILIC) column. Considering the limited availability of this special type of column and the importance of DTC residue analysis, several new HILIC columns were evaluated as alternatives to the ZIC-pHILIC column. Detection was carried out by ultraviolet light and by mass spectrometry (MS) on a single quadrupole mass spectrometer coupled to an electrospray ionization interface operating in negative mode. On nearly all tested columns, separation of dimethyldithiocarbamates, ethylenebis(dithiocarbamates), and propylenebis(dithiocarbamates) was achieved with ammonium acetate eluents (pH 6.8). However, due to ion suppression by the buffer and the limited alkaline pH stability, the tested silica-based columns were not suitable for the sensitive analysis of DTCs. The polymer-based iHILIC-Fusion was the only alternative that offered high MS sensitivity, when a buffer containing 15?mM aqueous ammonium hydroxide and 7.5?mM ammonium hydrogen carbonate (pH 9.8) was used, but the separation of the three DTC subclasses was poor. Thus, considering both selectivity and sensitivity, the originally proposed polymer-based ZIC-pHILIC column still outperformed all the tested newly available alternative HILIC columns. 相似文献
5.
Summary A metallic copper electrode housed in a suitable flowcell is shown to be a sensitive and versatile potentiometric detector for ion chromatography. This electrode may be used for direct or indirect detection of many inorganic anions and cations and also for organic acids. In the direct detection mode, electrode response is based on either complexation of copper ions at the electrode surface by eluted species, or on oxidation and reduction reactions for eluted species which are strong oxidants or reductants. Direct detection is therefore applicable to such species as amino acids, organic acids, chloride, bromide, iodide, chlorate, bromate and iodate. Indirect detection is possible for anions which do not complex copper ions, provided a copper complexing ligand (such as phthalate) is used in the eluent; cations which complex this ligand are also detectable. Indirect detection may be used for species such as nitrite, nitrate, acetate, formate, succinate, benzoate, alkaline earth ions and transition metal ions. Electrode calibration relationships are discussed and sample separations are presented, together with some typical detection limits attainable in the direct and indirect detection modes.Presented in part at a National Symposium on Ion Chromatography, held at the University of New South Wales, Kensington, Australia, Nov. 21, 1984. 相似文献
6.
Summary Separation behavior of fat soluble vitamins on various chemically bonded materials in non-aqueous reversedphases microcolumn
liquid chromatography has been investigated. The best performance was found on a polymer-based octadecyl bonded phase. Optimization
of separation for vitamins D2, D3, E and E acetate has been tried using this polymer-based column and it has been found that
a binary mobile phase consisting of acetonitrile and methanol gave complete separation of fat soluble vitamins. 相似文献
7.
In recent years the use of monolithic polymers in separation science has greatly increased due to the advantages these materials present over particle-based stationary phases, such as their relative ease of preparation and good permeability. For these reasons, these materials present high potential as stationary phases for the separation and purification of large molecules such as proteins, peptides, nucleic acids and cells. An example of this is the wide range of commercial available polymer-based monolithic columns now present in the market. 相似文献
8.
在YWG微粒硅胶柱上,研究了不同浓度的甲醇、乙醇作为梯度溶剂对PTH-亮氨酸、异亮氨酸、缬氨酸、丙氨酸、甘氨酸的k′和R_s的影响。结果表明,乙醇对这五个PTH氨基酸所给出的k′最为理想,既有适合的分离度又有较快的分离速度。最后,我们设计了以0.5、5、10、25%乙醇为阶段梯度的正己烷-氯仿(3:1)的洗脱条件,分离了16个PTH-氨基酸,全程分析时间为43分钟,比异丙醇的条件缩短1/4。 相似文献
9.
In this topical review, progress achieved in amperometric sensing of different analytes over conducting polymer-based hybrid electrocatalysts is summarized. We report a variety of synthetic methods and the resulting hybrid assemblies, with the effectiveness of such strategies, for designing conjugated polymer-based hybrids as robust sensors for amperometric detection. Beyond incorporation of metal nanoparticles, metal-oxide and non-oxide semiconductors, carbon-based nanomaterials (nanotubes, graphene, and graphene oxide), and special dopant ions are also discussed. Moreover, some particularly interesting miscellaneous approaches, for example photo-amperometric sensing or use of overoxidized polymers, are also emphasized. Determination of dissolved gases (for example O2, NO, and NO2), ions (sulfite, nitrite, nitrate, chlorate, bromate, and iodate) and smaller and larger molecules (for example H2O2, ascorbic acid (AA), dopamine (DA), urea (UA), amino acids, hydrazine, NADH, serotonin, and epinephrine) is discussed. These achievements are reviewed from the materials perspective, addressing both synthetic and electrocatalytic aspects of the polymer-based modified electrodes. Beyond simple or more sophisticated mixing, a wide range of methods of preparation is presented, including chemical (one-pot polymerization, impregnation), electrochemical (co-deposition, doping type inclusion, etc.) and combined strategies. Classification of such synthetic routes is also included. However, it is important to note that we omit studies in which conducting polymers alone were used for determination of different species. Furthermore, because excellent reviews—cited in this work also—are available on immobilization of biomolecules (for example enzymes) for biosensing purposes, this topic, also, is excluded. 相似文献
10.
A liquid chromatographic method using indirect conductimetric detection is proposed for the determination of low levels of organic compounds, which does not require any special functional characteristics of the analyte. The signal detected is proportional to the molar concentration of the analyte and independent of its nature. The detector response is linearly dependent on analyte concentrations over at least three orders of magnitude. The basis of the detection is to create a conducting background, which will decrease on elution of the organic compounds. The theory of the method is discussed, with special reference to the quantitative displacement of the conducting species of the mobile phase from the column by the analyte on sample injection. The proposed method has been applied to study the chromatographic behaviour of twenty-one amino acids, where a 5 -μm Econosil CN column was used as the stationary phase with a mixture of water-acetonitrile-tetrahydrofuran (70:20:3) containing 1 mM perchloric acid or trichloroacetic acid as the mobile phase. The proposed method allows as little as 10 ng of each amino acid to be determined. 相似文献
11.
12.
Microcantilever bending can be reversibly driven by conformational changes of phosphate containing polyelectrolyte brushes when exposed to different pH or salt solutions. The deflection of the cantilevers allows a detailed analysis of the properties of polymer brushes, while these systems are also a first step toward polymer-based nanoactuators. 相似文献
13.
N. Tsevegsüren K. Aitzetmüller L. Brühl Gisela Werner 《Journal of separation science》2000,23(5):360-366
Seed oils from the Compositae plant family are known to contain a variety of unusual fatty acids. Subsequent to the recent discovery of γ‐linolenic acid in Saussurea and Youngia, further Mongolian Compositae species were investigated for their seed oil fatty acid composition. A number of δ3trans‐fatty acids (16 : 1δ3t, 18 : 1δ3t and 18 : 3δ3t, 9c, 12c) were found in the seed oils of Heteropappus hispidus and Asterothamnus centrali‐asiaticus. The latter fatty acid, but not the trans‐monoenes, was also found in one species of Artemisia. These unusual fatty acid isomers were characterized by capillary gas‐liquid chromatographic (GLC) separations in combination with other chromatographic techniques (analytical thin layer chromatography, TLC and preparative argentation TLC), and infrared spectrocsopy (IR). Their identity was further confirmed by co‐chromatography with other seed oils known to contain these trans‐fatty acids. The fact that within the Compositae plant family there are apparently two or three distinct groups of genera containing δ3trans‐fatty acids is discussed. 相似文献
14.
整体柱离子色谱的研究进展 总被引:1,自引:0,他引:1
该文介绍了离子色谱的分类,整体柱的分类、制备及特点,并以此为依据归纳总结了常规整体柱在离子色谱中的应用和毛细管整体柱在毛细管离子色谱中的应用,其中包括硅胶基质整体柱和聚合物基质整体柱,评述并展望了整体柱离子色谱的发展前景. 相似文献
15.
16.
17.
Two chiral stationary phases (CSPs) based on optically active (3,3′-diphenyl-1,1′-binaphthyl)-20-crown-6 covalently bonded to silica gel were utilized for the first time for the resolution of racemic β-amino acids using high performance liquid chromatography. All of the 10 β-amino acids tested were resolved on the CSP containing residual silanol-protecting n-octyl groups, while only five β-amino acids were resolved on the CSP containing residual silanol groups. The superiority of the CSP containing residual silanol-protecting n-octyl groups and the characteristic retention behaviors of the two enantiomers on the CSP were rationalized to stem from the removal of the residual silanol groups, which can otherwise induce the non-enantioselective retention of the analytes, and the improved lipophilicity of the CSP. The elution orders of the two enantiomers of β-amino acids were identical on the two CSPs and, consequently, it was concluded that the two CSPs were concluded to utilize identical chiral recognition mechanisms. The different elution orders of the analytes were proposed to be attributed to the presence or absence of π-π interactions between the CSP and analytes. 相似文献
18.
Three chiral stationary phases, obtained by grafting silica gel with (-)-trans-1,2-cyclohexanediamine, were studied for the resolution of α-amino acids by ligand-exchange chromatography. The packings were prepared by bonding the chiral ligand to silica gel via different hydrocarbon spacers. Separation of the optical isomers was accomplished by eluents containing a constant concentration of copper(II) acetate (0.05mM). The elution sequence of amino acids was found to be dependent on the grafting reaction selected to prepare the chiral packings. 相似文献
19.
A. Péter G. Török G. Tóth W. Van Den Nest G. Laus D. Tourwé D. W. Armstrong 《Chromatographia》1998,48(1-2):53-58
Summary High-performance liquid chromatographic and gas chromatographic methods were developed for the separation of unusual secondary
aromatic amino acids. Amino acids containing 1,2,3,4-tetrahydroisoquinoline, 1,2,3,4-tetrahydronorharmane-1-carboxylic acid
and 1,2,3,4-tetrahydro-3-carboxy-2-carboline moieties were synthetized in racemic or chiral forms. The high-performance liquid
chromatography was carried out either on a teicoplanin-containing chiral stationary phase or on an achiral C18 column. In the latter case the diastereomers of the amino acids formed by precolumn derivatization with the chiral reagents
2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl isothiocyanate or 1-fluoro-2,4-dinitrophenyl-5-L-alanine amide were separated. The gas chromatographic
analyses were based on separation on a Chirasil-L-Val column.
Presented at: Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 3–5, 1997 相似文献
20.
毛细管气相色谱法鉴定分析杆菌 总被引:1,自引:0,他引:1
本文利用OV-101熔融石英毛细管柱,对15种标准分枝杆菌的色谱特征进行了研究,得到了特异性指纹图。并对42株临床菌株进行了鉴别。 相似文献