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1.
High-performance TLC and 31P-NMR were assessed as methods of observing the presence of numerous low polarity phospholipids: bis-phosphatidic acid (BPA),
semi-lyso bis-phosphatidic acid (SLBPA), N-acyl phosphatidylethanolamine (NAPE), N-(1,1-dimethyl-3-oxo-butyl)-phosphatidylethanolamine (diacetone adduct of PE, DOBPE), N-acetyl PE, phosphatidylmethanol (PM), phosphatidylethanol (PEt), phosphatidyl-n-propanol (PP), phosphatidyl-n-butanol (PB). Both techniques are non-discriminative and do not require the prior isolation of individual lipids. It appears
that 2D TLC is superior to 31P NMR in the analysis of low polarity phospholipids. All phosphatidylalcohols were well separated by 2D TLC. However, some
compounds which can present difficulty in separation by 2D-TLC (e.g., SLBPA and NAPE; or DOBPE and N-acetyl PE) were easily distinguished using 31P NMR so the methods are complimentary. A disadvantage of 2D TLC is that Rf values can vary with different brands and batches of TLC plates. The chemical shifts of 31P NMR were less variable, and so a library of standards may not be necessary for peak identification. Another advantage of
31P NMR is the ease of quantification of phospholipids. The applicability of the methods was tested on natural extracts of fish
brain and cabbage stem. 相似文献
2.
Information on the phosphorus (P) forms of pasture soils is central to agricultural and environmental sustainability. We used
a combination of 31P nuclear magnetic resonance (NMR) spectroscopy of NaOH–EDTA extracts and sequential fractionation to investigate P forms,
with an emphasis on organic P in relation to environmental and biophysical variables, in 24 diverse pasture soils taken from
around New Zealand (organic C 19–102 g kg−1, total P 116–2746 mg kg−1, pH 5.2–7.0). Soils were separated by cluster analysis of soil physicochemical properties and sequentially extracted P pools
into those either derived from volcanic-ash materials or not. This separation was also evident for organic P species in NaOH–EDTA
extracts, which removed about 75% of total soil organic P. The major organic P compound class was monoesters (24–60% of extracted
P), made up of 14 to 91% myo-inositol hexakisphosphate. The next largest organic P class was diesters (0–4% of P extracted), which were enriched in volcanic-ash soils
(monoester to diester ratio = 14) compared to non volcanic-ash soils (ratio = 30). Correlation analysis indicated that mean
annual temperature had a significant negative and positive effect on monoester and diester concentrations, respectively. This
was attributed to better physical protection of monoesters (especially inositol phosphates) from mineralization, and increased
diesters from microbial activity and biological turnover. The anomalous behaviour of volcanic-ash soils was attributed to
slow mineralization and the sampling of soils at different times of year without full knowledge of the large and highly dynamic
microbial biomass P pool which is predominantly diesters. 相似文献
3.
Emmanuel Hatzakis Alexia Agiomyrgianaki Photis Dais 《Journal of the American Oil Chemists' Society》2010,87(1):29-34
31P-Nuclear magnetic resonance (NMR) spectroscopy was employed to detect and quantify free glycerol in virgin olive oils originating from various regions of Greece. This analytical method was based on the derivatization of the hydroxyl groups of glycerol with the tagging reagent 2-chloro-4,4,5,5-tetramethyldioxaphospholane, and identification of the phosphitylated compound on the basis of 31P chemical shifts. Quantification of glycerol in olive oils was accomplished by integration of the appropriate signals in the 31P NMR spectrum and the use of the phosphitylated cyclohexanol as internal standard. A linear correlation was observed between the glycerol content and 1,3-diacylglycerols and free acidity indicating that glycerol is the final product of the partial hydrolysis of triacylglycerols. 相似文献
4.
Abdolraouf Samadi-Maybodi Naser Goudarzi Christopher W. Kirby Yining Huang 《Journal of surfactants and detergents》2008,11(1):49-54
Silicate anions were studied using 29Si NMR to investigate the structure-directing effect of a surfactant (sodium dodecylsulfate-SDS) on the distribution of silicate
species present in alkaline silicate solutions. The distribution of the anions in the presence of polyelectrolytes was also
investigated by 29Si NMR through the use of different bases including tetramethyl ammonium hydroxide (TMAOH) and sodium hydroxide (NaOH). Both
SDS and the polyelectrolytic solutions were shown to stabilize low molecular weight silicate species and thus inhibit polymerization.
相似文献
Abdolraouf Samadi-MaybodiEmail: |
5.
In the oxidation of cyclohexene with H2O2in monophasic tri-n-butylphosphate (TBP) solution catalyzed by Keggin-type 12-heteropolyacids, i.e., H3PMo12-xW
x
O40(x=0–12), several peroxo species were observed by 31P-NMR spectroscopy in lower field than the original heteropolyacids. Their composition varied regularly with that of the starting catalyst. The P-containing peroxo species formed was deduced as [PM4O8(O2)8]3-(M = Mo, W). The peroxo species formed more easily with a decrease in the W content, x of H3PMo12-xWxO40. It was further indicated from the reactivity with cyclohexene and the comparison with catalytic performance that W-rich peroxo species were catalytically more active than Mo-rich peroxo species for the oxidation of cyclohexene in this reaction system. 相似文献
6.
In this study, proton NMR spectroscopy (200 MHz) was used for quantifying the content of ethyl esters in known mixtures of
soybean oil and ethyl soyate (biodiesel). For this purpose, the peak areas of ester ethoxy and glycerol methylenic peaks in
the region of 4.05–4.40 ppm were measured and a calibration plot of the respective peak areas vs. the known composition of
the oil/ethyl ester mixtures was used. The transesterification values determined in this way were compared with viscosity
and total glycerol determinations and a good correlation was obtained. Therefore, for routine analysis, the conversion (in
%) of oil to ethyl esters was determined. The methodology presented in this work proved to be quicker and simpler than others
reported in the literature, such as GC and/or HPLC. 相似文献
7.
Visualization of Bile Homeostasis Using <Superscript>1</Superscript>H-NMR Spectroscopy as a Route for Assessing Liver Cancer 总被引:1,自引:1,他引:0
Changes in bile synthesis by the liver or alterations in the enterohepatic circulation due to a variety of etiological conditions
may represent a novel source of liver disease-specific biomarkers. Bile from patients with liver diseases exhibited significant
changes in the levels of glycine- and taurine-conjugated bile acids, phospholipids, cholesterol and urea relative to non-liver
disease controls. Cholangiocarcinoma and non-malignant liver diseases (NMLD) showed the most significant alterations. Further,
hepatocellular carcinoma (HCC) could be differentiated from NMLD (p = 0.02), as well as non-liver disease controls (p = 0.02) based on the amounts of bile acids, phospholipids and/or cholesterol. HCC also differed with cholangiocarcinoma although
not significantly. Urea increases somewhat in non-malignant liver disease relative to non-liver disease controls, while the
bile acids, phospholipids and cholesterol all decrease significantly. The ratio between some major bile metabolites also distinguished
NMLD (p = 0.004–0.01) from non-liver disease controls. This snapshot view of bile homeostasis, is obtainable from a simple nuclear
magnetic resonance (NMR) approach and demonstrates the enormous opportunity to assess liver status, explore biomarkers for
high risk diseases such as cancers and improve the understanding of normal and abnormal cellular functions. 相似文献
8.
有机磷酸31P-NMR谱图研究 总被引:7,自引:0,他引:7
报道了目前国内外常用水处理药剂中的四类有机磷化合物的^31P-NMR谱。其中包括小分子有机磷酸、大分子有机磷酸、有机亚磷酸和有机次磷酸。 相似文献
9.
10.
1H NMR can be used to determine the epoxide yield rapidly in the oxidation of squalene. Moreover, unequivocal distinction can
be made between internal and terminal epoxide bonds. To underline the power of this technique, different stoichiometric and
catalytic epoxidation procedures were carried out using squalene as substrate. They were characterized in terms of substrate
conversion and regioselectivity of the epoxide fraction. 相似文献
11.
David L. Compton Karl E. Vermillion Joseph A. Laszlo 《Journal of the American Oil Chemists' Society》2007,84(4):343-348
The acyl migration kinetics of neat 2-monoacylglycerol (2-MAG) to form 1-MAG was determined using 1H NMR spectroscopy to monitor the β-proton integration ratios of the two species over time. 2-MAG was synthesized by the Novozym
435-catalyzed alcoholysis of soybean oil and isolated by solvent extraction or molecular distillation at a mole fraction (X
2-MAG) of 0.94 relative to total MAG. The kinetics parameters of the neat 2-MAG acyl migration were investigated over the temperature
range of 23–80 °C. The 2-MAG mol fraction remained unchanged at 23 °C over the course of 168 h and reached an equilibrium
of X
2-MAG = 0.09 at only 80 °C. Modeling of the kinetics data revealed a 2-MAG half life (t
1/2) of 3,500 and 22.8 h at 23 and 80 °C, respectively, with an activation energy of 79.0 ± 6.5 kJ mol−1. The use of 1H NMR spectroscopy proved an expedient method for monitoring the acyl migration in 2-MAG compared to other reported methods
(e.g. GC, HPLC, and 13C-NMR spectroscopy), requiring no sample manipulation and minimizing the deleterious effects of high temperatures and solvent
exposure.
Product names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard
of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may
be suitable. 相似文献
12.
G. A. Nagana Gowda Narasimhamurthy Shanaiah Amanda Cooper Mary Maluccio Daniel Raftery 《Lipids》2009,44(6):527-535
Bile acids constitute a group of structurally closely related molecules and represent the most abundant constituents of human
bile. Investigations of bile acids have garnered increased interest owing to their recently discovered additional biological
functions including their role as signaling molecules that govern glucose, fat and energy metabolism. Recent NMR methodological
developments have enabled single-step analysis of several highly abundant and common glycine- and taurine- conjugated bile
acids, such as glycocholic acid, glycodeoxycholic acid, glycochenodeoxycholic acid, taurocholic acid, taurodeoxycholic acid,
and taurochenodeoxycholic acid. Investigation of these conjugated bile acids in human bile employing high field (800 MHz)
1H-NMR spectroscopy reveals that the ratios between two glycine-conjugated bile acids and their taurine counterparts correlate
positively (R
2 = 0.83–0.97; p = 0.001 × 10−2–0.006 × 10−7) as do the ratios between a glycine-conjugated bile acid and its taurine counterpart (R
2 = 0.92–0.95; p = 0.004 × 10−3–0.002 × 10−10). Using such correlations, concentration of individual bile acids in each sample could be predicted in good agreement with
the experimentally determined values. These insights into the pattern of bile acid conjugation in human bile between glycine
and taurine promise useful clues to the mechanism of bile acids’ biosynthesis, conjugation and enterohepatic circulation,
and may improve our understanding of the role of individual conjugated bile acids in health and disease.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
13.
Three oil samples obtained from sacha inchi (Plukenetia volubilis L.) seeds were studied by means of FTIR and 1H NMR. Frequency data of the most significant bands of the IR spectrum of this oil are given. These data show that sacha inchi
oil has a high degree of unsaturation. The same fact is deduced from the ratio between the absorbance of the bands due to
the stretching vibrations of the cis olefinic CH double bonds at 3010.5 cm−1 and to the methylene symmetrical stretching vibrations at 2855.1 cm−1. The proportions of monounsaturated, polyunsaturated, and saturated acyl groups were predicted from the frequency of some
IR bands, and these were in satisfactory agreement with the values obtained through FAME generation and their quantification
by GC. Likewise, simple observation of the 1H NMR spectra provided a great deal of information about sacha inchi oil, with regard not only to the relative proportions
of the different acyl groups but also to their nature. Thus, the presence of γ-linolenic acyl groups was discounted. Furthermore,
the area of some 1H NMR signals was used to determine the proportion of saturated and mono-, di-, and triunsaturated acyl groups, which also
were in satisfactory agreement with the values obtained by classical methods. IR and 1H NMR determinations take very little time in comparison with classical methods and do not require chemical manipulation or
transformation of the sample. A comparison was also made between the compositions of sacha inchi and linseed oil. Both oils
are important sources of the healthful n−3 linolenic acyl groups, and sacha inchi also contains high proportions of the n−6
linoleic acyl groups. 相似文献
14.
Characterization of the lipid fraction of raw cow and buffalo milk samples, collected in different breeding areas in Apulia,
a region of southern Italy, were performed by means of 1H NMR. The aim of this work was to establish whether FA composition data obtained by 1H NMR can be used in the differentiation of buffalo and cow milk samples according to species. A complete assignment of the
signals present in the spectrum was attempted by COSY, heteronuclear coherence spectra. Quantification of FA was carried out
by inserting the integrals of particular peaks in suitable calculations. Multivariate statistical analysis, conducted on the
results of the quantification, permitted buffalo and cow milks to be distinguished. 相似文献
15.
The roles of adsorbed hydroxyl radicals, OH, at a high temperature and adsorbed hydrogen atoms, H, in an acidic solution were
investigated in the electrochemical reactions on Pt electrode by using potentiodynamic polarisation experiment, cyclic voltammetry
and constant-potential electrolysis combined with UV/VIS analysis. From the analysis of the polarisation curves obtained from
Pt electrode in a 0.185 M H3BO3 solution at 473 K, it was found that the reducing capability of dissolved hydrogen is significantly enhanced due to the increases
of the mass transfer and the electron transfer rates. Especially, it is suggested that the stable Pt-OHad plays a significant role in the passivation reaction in the potential range from 0.60 to 0.75 VSHE. From the analyses of the experimental results for the electrochemical reduction of UO22+ ions on Pt surface in a 1.0 M HClO4 solution, it is recognised that the reduction reaction of UO22+ to U4+ ions is strongly dependent on the hydrogen atoms adsorbed on Pt electrode (indirect reduction of UO22+) as well as on the electrons transferred from Pt electrode (direct reduction of UO22+). In addition, the reduction mechanism of UO22+ ions involved in Pt-Had is also proposed. 相似文献
16.
1H NMR spectra of cetyltrimethylammonium bromide (CTAB) micellar solutions in the absence and presence of sodium anthranilate
(NaAn) have been recorded. Studies were performed at a fixed CTAB concentration in the presence of different NaAn concentrations.
The specificity of the functional group attached to the salt in producing changes (i.e., viscoelasticity) in CTAB micellar
solutions was explored. It was concluded that the nature of the salt counterion together with its intercalation/adsorption
in the head group region is the principal cause of viscoelasticity. 相似文献
17.
Rapid Identification and Relative Quantification of the Phospholipid Composition in Commercial Lecithins by <Superscript>31</Superscript>P NMR 下载免费PDF全文
Ying Yang Richard Hiserodt Jing Li 《Journal of the American Oil Chemists' Society》2017,94(7):885-892
31P NMR analysis of samples prepared in a sodium cholate detergent system was used as a method for the identification and quantification of enzymatic hydrolysis products of lecithin. To precisely characterize all of the hydrolysis products from commercial lecithin, a series of enzymatic reactions of each phospholipid with phospholipase PLA1 were conducted and monitored by 31P NMR at different times. Twenty-six phosphorus-containing hydrolysis products from six classes of phospholipids (PC, PI, PS, PE, PG, PA) were found and determined by 31P NMR measurement. The impact of pH on the chemical shift values for these hydrolysis products was observed and reported. To the best of our knowledge, this is the first report of 31P-NMR chemical shift values for entire lyso-phospholipids hydrolyzed from 6 classes of phospholipids. Rapid and routine analysis of phospholipid composition in commercial lecithins by 31P NMR was achieved without the need of phospholipid standards. 相似文献
18.
Zi Teng Chong Liu Xiaoquan Yang Lin Li Chuanhe Tang Yueming Jiang 《Journal of the American Oil Chemists' Society》2009,86(5):409-417
The substitution of CaCl2 by MgCl2 was undertaken in Deak’s two-step process of separating the soybean 11S and 7S globulins, aiming at higher purities and lower
phytic acid (PA) contents of recovered protein fractions. The effects of pH and the addition of NaCl were also evaluated.
Compared with CaCl2, MgCl2 reduced the PA content of the 11S-rich fraction by 63–71% but increased that of the 7S-rich fraction by 14–28%, depending
on pH. Correspondingly, more Ca2+ was recovered in the 11S-rich fraction, while more Mg2+ co-precipitated with the 7S-rich fraction. NaCl increased the purity of the 11S-rich fraction and reduced its PA content,
but the purity of the 7S-rich fraction was reduced by using 50–100 mM NaCl. Lowering pHs from 6.4 and 4.8 to 5.6 and 4.0 in
the two precipitation steps increased the yield of both fractions. The optimized fractionating procedure was as follows: the
11S-rich fraction was precipitated at pH 5.8 by using 5 mM MgCl2, 10 mM NaHSO3 and 20 mM NaCl, followed by the precipitation of the 7S-rich fraction at pH 4.5. The new method provided both fractions with
satisfactory protein yields (22% for 11S and 16% for 7S), purities (88% for 11S and 80% for 7S) and PA contents (0.356% for
11S and 0.882% for 7S). 相似文献
19.
Inger B. Standal Angelika Praël Lesley McEvoy David E. Axelson Marit Aursand 《Journal of the American Oil Chemists' Society》2008,85(2):105-112
The objective of this study was to test the possibility of using lipid profiles obtained by gas chromatography (GC) and 13C nuclear magnetic resonance (NMR) in authentication of cod liver oils according to wild/farmed and geographical origin. GC
and 13C-NMR data of cod liver oil from wild and farmed fish from different locations in Norway and Scotland were obtained, and analyzed
by principal component analysis (PCA) and linear discriminant analysis (LDA) to test if it was possible to differentiate oil
from wild and cultured cod (Gadus morhua L.), and to further elucidate differences between fish from the different farms/catch area. Cod liver oils of wild and farmed
origin were clearly separated in the PCA score plot both from GC and NMR data. From NMR data it was also possible to observe
groupings based on geographical origin (farm/catch area) of the different samples. Using LDA with cross validation the wild/farmed
classification rates were 97% for GC data and 100% for NMR data. In the classification of cod liver oils according to geographical
origin (38 samples from six different farms/catch area), the correct classification rate was 63% for GC data and 95% for NMR
data. 相似文献
20.
Nitrogen (N) leaching under grazed pastures can be very high directly under urine spots. The amount of N which is returned
by one excretion of urine or dung can locally exceed 1000 kg ha−1 a−1 which is far more than the uptake by surrounding plants during one grazing period. We therefore quantified the contribution
of N deriving from urine and dung to the total N leaching under urine and dung patches. Dung N and urine N was separately
sampled from a cow feed with 15N labelled grassilage, and were amended on lysimeters in October 2000 and October 2001. Lysimeters (350 mm diameter and 800 mm
length) were filled with sand, and an intact grass sod from a pasture, 4 lysimeter each were amended with the 15N labelled dung and urine; 4 lysimeters without an application of dung or urine served as control. During 11 months after
dung and urine amendment the amount of leachate was monitored and leachate was analysed for nitrate, ammonium and total N.
15N in these fractions was measured. Dung and urine applications of 1052 and 1030 kg N ha−1 in autumn increased N leaching. Leaching loss of nitrate and dissolved organic N deriving from dung was only 37 kg N ha−1 in both years, whereas under urine patches 447 kg nitrate-N ha−1, 108 kg N ha−1 ammonia-N and 53 kg ha−1 dissolved organic N leached on average of both experimental years. N not deriving from dung and urine exceeded the leached
N under the control by about 36 and 136 kg ha−1 on average of both years, suggesting the contribution of different priming processes. 相似文献