共查询到20条相似文献,搜索用时 0 毫秒
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W. L. Hollaway A. S. Bhown J. E. Mole J. C. Bennett 《Journal of separation science》1978,1(3):177-178
New methods for peptide separation are being developed. Resolution of peptide mixtures on HPLC with good reproducibility indicates the progress that has already been made in development of supports with useful separation capabilities. At present adsorptive characteristics of the stationary phases may place limitations on the applicability of the technique to underivatized peptides. Hopefully, the application of ionpairing techniques and the development of new support materials will expand the range of application for protein and peptide purification. 相似文献
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Fahad J. Al-Shammary 《Journal of separation science》1990,13(5):309-311
This paper reviews solid phase extraction as applied to the sample preparation of catecholamines and biologically active peptides. The mechanisms used in solidphase extraction are: non-polar, polar, ion-exchange, and covalent. 相似文献
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Haleem J. Issaq King C. ChanJosip Blonder Xiaoying YeTimothy D. Veenstra 《Journal of chromatography. A》2009,1216(10):1825-1837
This review discusses different liquid chromatographic and capillary electrochromatographic approaches to the separation and quantitation of peptides using silica-based and polymeric-based columns with emphasis on liquid chromatography. Mass spectrometry detection and quantitation of peptides using labeled and label-free procedures, will also be discussed, as well as the effect of amino acids’ properties on the solubility of peptides, an important parameter that influences the selection of the mobile phase. A discussion of different column packing materials, reversed-phase, cyclodextrins, macrocyclic antibiotics, porous graphitic carbon, mixed-phases, and normal-phase will be included, as well as a short discussion of multi-dimensional approaches for the separation of complex peptide mixtures. 相似文献
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Simple procedures are presented for separating the enantiomers of α-methyldopa, 5-hydroxytryptophan, tryptophan, triiodothyronine and thyroxine, which require neither special sorbents nor difficult-to-obtain or unstable reagents. The method for α-methyldopa, 5-hydroxytryptophan and tryptophan is based on the use of L-phenylalanine copper complex as the chiral constituent of the mobile phase; LiChrosorb® RP-18 serves as the stationary phase. The procedure for triiodothyronine and thyroxine is grounded on the L-proline copper complex as the chiral reagent and LiChrosorb® Si 60 as the stationary phase. In all observed cases, the D-enantiomer is eluted prior to the respective L-enantiomer. Chirality inversion of the mobile phase (application of the D-phenylalanine copper complex) reverses the order of elution; a racemic eluent (DL-phenylalanine copper complex) leads to no separation. In addition to the enantiomers of α-amino acids, the enantiomers of α-hydroxy acids (mandelic acid) can be separated. 相似文献
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Ammonia-nitrogen feedstock streams, free of oxygen containing impurities, are essential reagents for fabricating low oxygen contaminated nitride films. An analytical method is described for determining part per billion levels of oxygen containing impurities, which are converted to nitric oxide (NO) through reaction with microwave discharge produced active nitrogen. Quantitative determinations are then based on detecting the resulting chemiluminescence of NO at characteristic wavelengths. This metastable transfer spectrometric method (MTES) provides direct measurements of oxygen impurities over the 14 to 500 ppb region and has dynamic range extending to 200 ppm. The method, unparalleled in its measurement sensitivity for oxygen impurities in flowing nitrogen gas streams, is calibrated with an NBS standard and applied to the determination of the purification efficiency of an on-line resin system for removal of O2, CO and NO from ammonia-nitrogen mixtures. Gaseous streams, doped deliberately in the 0.2 to 100 ppm level with either O2, CO or NO following purification were found to contain less than 10 ppb of the residual impurity. A commercially available 1% ammonia in nitrogen semiconductor grade reagent (99.999%) is shown by MTES to be contaminated with 470 ppb of oxygen impurities. 相似文献
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A method is described for the qualitative and quantitative determination of configurational isomers of astaxanthin. It is based on the esterification of astaxanthin with (—)-camphanic acid chloride and analysis of the corresponding diesters by HPLC. 相似文献
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This paper shows how simply and yet very rapidly fatty acid esters of monohydric alcohols, but particularly partial and full fatty acid esters of fully hydric alcohols can be separated and determined by means of high-pressure liquid chromatography on LiChrosorb RP-8 with methanol/water. We have separated quantitatively the methylesters of the fatty acids C8:0 to C22:0 and C24:0, the i-propyl-, i-butyl-, n-hexyl- and i-octyl-esters of the even-numbered fatty acids C8:0 to C18:0, mono- and difatty acid esters of the 1,3-bis-(2-hydroxyethyl)-5,5-dimethyl-hydantoin, mono-, di- and triesters of the trimethylolpropane as well as the tetraesters of the penta-erythrite. 相似文献
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Glycation is a common class of nonenzymatic posttranslational modifications relevant for several diseases and cell aging in
general, such as D-glucose-derived modifications at the ɛ-amino groups of lysine residues in blood proteins, especially albumin, immunoglobulin,
and hemoglobin, for diabetic patients. These Amadori compounds are identified on the peptide level after enzymatic digestion
and chromatographic separation by mass spectrometry. Their syntheses usually rely on a global glycation approach. Both areas
require the reliable separation of glycated peptides from their unmodified congeners present in different ratios, which is
typically not achieved by standard eluent systems in ion-pairing RP-HPLC (IP-RPLC). Here, we compare aqueous acetonitrile
and methanol gradients containing either trifluoroacetic acid (TFA) or heptafluorobutyric acid (HFBA) as ion-pairing agents
to separate such peptide pairs. TFA-containing eluents resulted in rather low resolutions, and the glycated and unglycated
peptides often coeluted. HFBA increased the retention times of the unmodified peptide more than for the glycated peptide thereby
improving the separation of all eight studied peptide pairs, even achieving baseline separations for some sequences. Thus
the use of HFBA as ion-pair reagent provides a universally applicable eluent system in IP-RPLC to separate glycated peptides
from their unmodified counterparts, even at the preparative scale required for synthetic peptides. 相似文献
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A method is described for the qualitative and quantitative determination of configurational isomers of zeaxanthin (=3,3′ -dihydroxy-β, β -carotene) and lutein (=3,3′ -dihydroxy-α -cartotene). It is based on the reaction of these zeaxathin and lutein isomers with (S)-(+)-α-(1-naphthyl) ethyl isocyanate to afford diastereomeric dicarbamates, which are analyzed by HPLC. 相似文献
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Summary The sensitive detection of volatile, methylated selenium and tellurium compounds based on capillary gas chromatography coupled to fluorine-induced chemiluminescence detection is described. The method requires no sample derivatization, and the detection limits for selenides and tellurides (low pg range) are the lowest reported to date. This technique can resolve and speciate complex mixtures of methylated tellurium, selenium, and sulfur gases and is useful for analysis of selenium and tellurium gases in environmental samples that also contain usually interfering reduced sulfur gases. Applications of the technique for analysis of bacterial and fungal headspace samples are presented. 相似文献
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Isocratic conditions are described for the separation, identification and quantitation of selected phenolic antioxidants and related compounds by high performance liquid chromatography on a reverse phase microparticulate ODS column. Mobile phases containing 0.05 M lithium perchlorate in aqueous methanol are used. Three detection systems: ultraviolet; fluorescence; and electrochemical detectors are connected in tandem. The use of these three detection systems in sequence as additional means for separation, identification, and quantitation is demonstrated. Other advantages of the system include speed of analyses and improved detection. The ? values and detector responses at 2 settings per detector for 12 compounds are reported. 相似文献
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《Analytical letters》2012,45(3):567-579
ABSTRACT A resin (I) containing imidazolylazo functional group has been used for the separation and preconcentration of palladium(II) and silver(I) from other metal ions in synthetic mixture, ores, alloys and medicinal samples. No interference could be observed from alkali and alkaline earth metal. Palladium(II) is quantitatively separated from ores and platinum wire without interferences. 相似文献