13C NMR定量分析一乙醇胺（MEA）与CO2的吸收和解吸特性

13C NMR是一种有效的测定有机胺与CO2反应过程中离子浓度变化的检测手段。本文采用13C NMR分析了一乙醇胺(MEA)吸收与解吸CO2过程,吸收与解吸实验温度分别在313K和393K下进行。结果表明,吸收CO2过程中生成了MEA氨基甲酸盐、质子胺MEAH+与HCO3-/CO32-,并且CO2与MEA反应时先生成MEA氨基甲酸盐,当溶液吸收的CO2担载量达到0.455molCO2/mol胺时,才产生HCO3-/CO32-离子。在MEA吸收CO2过程中,MEA氨基甲酸盐的摩尔分数先增加后减少。在解吸过程中,MEA氨基甲酸盐的摩尔分数同样先增加后减少。HCO3-/CO32-在解吸过程中很容易就能被解吸,而生成的MEA氨基甲酸盐中大约有75%在解吸过程中并没有被解吸。     

Rapid and direct quantitative analysis of positional fatty acids in triacylglycerols using 13C NMR

There is increasing evidence that the positional fatty acid composition (FAC) of TAG is more important than total FAC with regard to nutrition values of edible oils and fats. A rapid and direct regiospecific analysis of positional fatty acids in TAG using ¹³C NMR was developed to overcome the tedious conventional methods which involve enzymatic hydrolysis, Grignard chemical degradation, and chromatography analysis. A set of NMR data acquisition parameters and processing methods had proven their excellent versatility and applicability on various types of oils and fats, with systematic error of 1.0 mol%. It was found that there are discrepancies between the regiospecific analysis results obtained by the current method and by conventional methods. Probable acyl migration occurring in the hydrolysis process in conventional methods is a noted problem. As the current ¹³C NMR method is a direct measurement and no hydrolysis of the sample is needed, acyl migration during the analysis is eliminated. As a result, the saturation level is always higher at sn‐1, 3 positions and lower at sn‐2 position in TAG structure of oils in the regiospecific data obtained from the current ¹³C NMR than that from conventional methods. In the absence of laborious chemical derivatization, this method is simple, accurate, and user‐friendly for researchers, especially for nutritionists to support their nutritional studies from the perspective of positional FAC of edible oils and fats.     

13C Nuclear Magnetic Resonance Studies of Phenol-Formaldehyde Resins and Related Model Compounds 2 - Analysis of Sequence Structure in Resins

The paper reports ¹³C nuclear magnetic resonance spectra of novolac resins and the variation of the composition of the reaction mixture during the in situ preparation of resin. It is observed that in the initial stages of the reaction ortho substitution occurs; however the hemiacetal rather than the methylol derivative is observed. These methylol substituted intermediates are highly unstable and a better appreciation of the relative rates of structure formation can be obtained from an analysis of the methylene bridge region, para-para Bridges are the first to appear, the next are the ortho-para and finally the ortho-ortho linkages are observed. Analysis of the relative intensities of ortho and para bridge carbon atoms allows identification of the isomeric composition of the final resin. The proportion of each isomer depends on the catalyst used in synthesis of the resin.     

13C-NMR和近红外光谱研究PP序列结构

利用核磁共振碳谱和近红餐光谱法研究了聚丙烯（PP）微观序列结构,建立了精确测定PP立构规整度的近红外数学模型,该方法简便、快速、准确、重复性好,两者之间的相关性很好,尤其适用于工业生产的中间控制分析。     

Application of Silver Ion High-Performance Liquid Chromatography for Quantitative Analysis of Selected n-3 and n-6 PUFA in Oil Supplements

The aim of this study was to develop a simple method for simultaneous determination of selected cis/cis PUFA–LNA (18:2), ALA (18:3), GLA (18:3), EPA (20:5), and DHA (22:6) by silver ion high‐performance liquid chromatography coupled to a diode array detector (Ag‐HPLC‐DAD). The separation was performed on three Luna SCX Silver Loaded columns connected in series maintained at 10 °C with isocratic elution by 1 % acetonitrile in n‐hexane. The applied chromatographic system allowed a baseline separation of standard mixture of n‐3 and n‐6 fatty acid methyl esters containing LNA, DHA, and EPA and partial separation of ALA and GLA positional isomers. The method was validated by means of linearity, precision, stability, and recovery. Limits of detection (LOD) for considered PUFA standard solutions ranged from 0.27 to 0.43 mg L^?1. The developed method was used to evaluate of n‐3 and n‐6 fatty acids contents in plant and fish softgel oil capsules, results were compared with reference GC‐FID based method.     

反相高效液相色谱法同时测定3-羟基-2-萘甲酸和2-萘酚

研究采用反相高效液相色谱法C18柱,同时测定3羟基2萘甲酸和2萘酚,甲醇∶水=70∶30(体积比)为流动相,检测波长为225nm。3羟基2萘甲酸和2萘酚的相对标准偏差分别为0.6%、0.7%,回收率分别为100.4%～102.0%、97.50%～99.08%     

The tacticity of poly(tri-n-butyl tin methacrylate) determined by 13C n.m.r.

The tacticities of poly(tri-n-butyl tin methacrylate)s prepared with radical initiators at various temperatures have been measured by ¹³C n.m.r. As expected, the polymers are predominantly syndiotactic and this syndiotacticity decreases with an increase in temperature. The activation parameters governing the tacticity are similar to those published for poly(methyl methacrylate) but differ somewhat from values published for poly(trimethyl tin methacrylate).     

Structure of initial, ultimate and inner chain units of polybutadiene obtained with a rare-earth catalyst as revealed by C nuclear magnetic resonance spectroscopy

The structure of initial, ultimate and inner chain units in polybutadiene produced with NdCl₃. 3(i-PrOH)---HAl(i-Bu)₂was studied by means of ¹³C nuclear magnetic resonance spectroscopy. Initial units are shown to be predominantly of trans-CH₃CH=CHCH₂--- structure. Conversely, 90% of inner units have cis configuration. Ultimate units obtained by quenching with H₂O (D₂O) are predominantly of 1,2 structure. On the basis of the data obtained, the polymerization mechanism was discussed.     

Investigation of Conformational Behavior and Mobility in Linear Liquid Crystalline Polyesters by 13C Solid State NMR-Spectroscopy

Abstract

Splitting of resonance signal of CH₂ group of spacer was observed in ¹³C solid state NMR spectra of liquid crystalline (LC) polyester with siioxane spacer [-OC-Pb-OOC-CH = CH-COO-Ph-COO-CH₂?_? Si(CH₃)₂-O-Si(CH₃)2-CH₂-O-]_n in LC-state. We consider that there are two conformations of-COO-CH₂-Si(CH₃)2-group of spacer. These conformations are stabilized by steric interactions of CH₂ groups of siioxane fragments with ortho-protons of phenylene rings of mesogene. As a result, there are hindrances to both flips of the phenylene rings and conformational transitions in the spacers.     

Quantitative triacylglycerol analysis of whole vegetable seeds by1H and13C magic angle sample spinning NMR spectroscopy

High-resolution¹³C and¹H magic angle sample spinning nuclear magnetic resonance (NMR) spectra have been obtained and used to define the relative unsaturated acyl distribution of triacylglycerols in whole oil seeds. Inverse gated proton decoupled¹³C and¹H NMR spectra permit the quantitative analysis of seeds containing simple oils,e.g., sunflower seeds containing oleyl and linoleyl unsaturates only. More sensitive¹³C NMR techniques are necessary for the analysis of specific seed classes. One such class is the rapeseed, which is especially difficult due to its low oil content (≈ 2 mg oil/seed) and complex unsaturated acyl profile of oleyl, linoleyl, linolenyl, erucyl, and eicosenoyl. The Distortionless Enhancement by Polarization Transfer technique significantly improves sensitivity to the extent that single rapeseeds can be examined within an hour of acquisition time. Furthermore, some positional (1,3- or 2-glycerol attachment) groups can be identified leading to a partial estimation of the 1,3-, 2-acyl distribution.     

End-groups in polymers of 2-vinylnaphthalene and 4-vinylbiphenyl,prepared by polymerisations initiated by azobis(isobutyronitrile)

Polymerisations of 2-vinylnaphthalene and 4-vinylbiphenyl and copolymerisations of these monomers with methyl methacrylate have been initiated by azobis(isobutyronitrile) enriched in its methyl groups with carbon-13. The environments of (CH₃)₂C(CN)- end-groups in the copolymers have been examined by ¹³C nuclear magnetic resonance. It has been concluded that both aromatic monomers are more than twice as reactive as methyl methacrylate towards the primary radical.     

Conifer seed oils: Distribution of Δ5 acids between α and β chains by13C nuclear magnetic resonance spectroscopy

Nine seed oils from three different conifer families, already examined by gas chromatography and known to contain diene, triene, and tetraene C₁₈ and C₂₀Δ5 acids, have been reexamined by high-resolution¹³C nuclear magnetic resonance spectroscopy. The Δ5 acids are apparent only in the α-chains. This location is independent of chainlength, double-bond number, and the species considered and is probably a general factor of conifer seed oils. The spectra confirm the presence of oleic, linoleic, α-linolenic, and of Δ5 acids and give quantitative information about (total) n-6, n-3, and Δ5 acids that is in accord with that obtained by gas chromatography.     

Determination of petroselinic acid inUmbelliflorae seed oils by combined GC and13C NMR spectroscopy analysis

Synthetic triolein and tripetroselinin mixtures were examined by¹³C NMR spectroscopy, showing marked chemical shift differences of the olefinic carbon atoms. Peak height ratios were compared to weight values for quantitative determination of oleic and petroselinic acids in seed oils, since these two fatty acids are quantitated together by GC analysis. Values observed for NMR peak height ratios were fairly close and agreed well with weight ratios. From overall compositions of eleic and petroselinic acids obtained by GC and relative compositions given by¹³C NMR, petroselinic acid has been determined in tenUmbelliflorae seed oils.     

高效液相色谱法同时测定牙膏中的维生素B_2、维生素B_3和维生素B_6

建立了同时测定牙膏中维生素B_2、维生素B_3和维生素B_6的检测方法。样品经水分散溶解后,用丙酮沉淀杂质,采用Waters T3色谱柱分离,HPLC测定,实验优化了沉淀剂的选择及用量等条件。结果表明,待测维生素在各自浓度范围内线性良好,相关系数均大于0.999,方法检出限在0.60~1.20 mg/kg之间,在高中低三个添加水平的平均回收率为95.0%~103.7%,相对标准偏差为1.67%~6.96%。该方法具有前处理简单、定量准确、灵敏快速的特点,适用于牙膏中维生素B_2、维生素B_3和维生素B_6的定量分析检测。     

The study of natural epoxy oils and epoxidized vegetable oils by13C nuclear magnetic resonance spectroscopy

The¹³C nuclear magnetic resonance spectra ofVernonia galamensis seed oil and of epoxidized palm super olein, soybean oil and linseed oil have been recorded and interpreted. The chemical shifts of the major signals are assigned and semi-quantitative results are derived. The spectroscopic procedure provides a useful method of analyzing oils that contain epoxy acids. The epoxide function differs from a double bond in its influence on the chemical shifts of nearby carbon atoms.     

The conformational origin of flexibility and stiffness in poly(olefin sulphones) demonstrated by means of dynamic C n.m.r. measurements

From previous calculations of electrostatic energies which cause third order Markov correlations of orientation of the dipoles in poly(olefin sulphones) ---(SO₂---C---C---)_nSO₂---, the lack of a strong interaction of one dipole with its immediate neighbour is predicted in the alternating copolymers prepared with symmetrical olefins. Using an approach developed by Bovey to detect stiffness in polysulphones in solution by means of C¹³ spin-lattice relaxation time measurements upon carbons in the main chain it is shown that poly(but-2-ene sulphone) and poly(cyclohexene sulphone) do have significantly shorter correlation times for motion of their backbones, and are thus more flexible than poly(but-1-ene sulphone). In the flexible polymers the C---C bonds are predominantly trans in conformation so that neighbouring sulphone groups are sufficiently well separated in space that each has thermal motions independently of the other. Stiffness in poly(1-olefin sulphones) is thus a consequence of their C---C bonds being predominantly in a gauche conformation, which permits the close approach of each pair of adjacent dipoles and the development of strong mutual ordering through the dipoles' electric fields.     

13C n.m.r. study of poly[(S)-5-methyl-1-heptene] and poly(1-heptene) prepared by Ziegler-Natta catalyst

Isotactic homopolymers of high optical purity (S)-5-methyl-1-heptene and of 1-heptene have been prepared and studied by ¹³C n.m.r. The tacticity degree evaluation of the polymers was performed on the basis of skeletal methine or methylene carbon atoms resonances in terms of diads. Conformational properties of both polymers have been investigated and discussed on the basis of n.m.r. dynamic parameters.