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1.
Połatajko A Banaś B Encinar JR Szpunar J 《Analytical and bioanalytical chemistry》2005,381(4):844-849
Determination of selenomethionine in selenized yeast by HPLC–ICP MS has been revisited with the focus on recovery of this amino acid during the proteolytic digestion and chromatography steps. Recovery of the extracted selenium from an anion-exchange column was 100% but selenomethionine quantified by the method of standard additions accounted only for 67% of the selenium injected. Analysis (by size-exclusion LC–ICP MS) of the eluate collected before and after the selenomethionine peak showed the presence of oxidized selenomethionine (ca. 3%) and selenomethionine likely to be unspecifically associated with the biological matrix continuum (ca. 11%). This finding was validated by two-dimensional LC–ICP MS using a different elution order, i.e. size-exclusion anion-exchange. The approach developed enabled demonstration that more than 80% of selenium in the selenized yeast is actually present in the form of selenomethionine and suggests that many results reported elsewhere for the concentration of this vital amino acid in selenized yeast may be negatively biased. The research also provided insight into speciation of selenium in the solid residue after proteolytic extraction but the additional amount of selenomethionine recovered was negligible (<1.5%). 相似文献
2.
Summary The main phenolic compounds in dried extracts fromCynara scolymus (artichoke)—monocaffeoylquinic acids, dicaffeoylquinic acid, and flavonoids–have been separated by high-performance liquid
chromatography. By use of a narrow bore C18 column and an acidic mobile phase this HPLC method enabled improved separation within 31 min with significantly reduced solvent
consumption compared with other methods. The method was validated to demonstrate its linearity, precision, accuracy, and robustness.
Twelve commercial samples were analyzed. Monocaffeoylquinic acids were the most abundant phenolic compounds; the amounts present
ranged from 0.48 to 4.24%. The amounts of dicaffeoylquinic acids and flavonoids were smaller—from 0.03 to 0.52%. The method
is a good combination of efficiency and economy and should be especially useful for commercial applications. 相似文献
3.
Enantioseparation and determination of selenomethionine enantiomers in selenized yeast was investigated using chiral separation techniques based on different principles, coupled on-line to inductively coupled plasma mass spectrometry (ICP-MS) for selenium-specific detection. High performance liquid chromatography (HPLC) on a beta-cyclodestrin (beta-CD) column, cyclodextrin-modified micellar electrokinetic chromatography (CD-MEKC), gas chromatography (GC) on a Chirasil-L-Val column, and HPLC on a Chirobiotic T column have been investigated as the chiral separation techniques. For HPLC separation on the beta-CD column, and also for CD-MEKC, selenomethionine enantiomers were derivatized with NDA/CN(-). For chiral separation by GC, selenomethionine enantiomers were converted into their N-trifluoroacetyl (TFA)-O-alkyl esters. The developed hybridation methodologies are compared with respect to enantioselectivity, sensitivity and analysis time. The usefulness of the best-suited method [HPLC (Chirobiotic T)-ICP-MS] was demonstrated by its application to the successful chiral speciation of selenium and D-and L-selenomethionine content determination in selenized yeast. 相似文献
4.
I. A. Lebedev B. F. Myasoedov L. I. Guseva 《Journal of Radioanalytical and Nuclear Chemistry》1974,21(1):259-266
The sorption of transplutonium (TPE), rare-earth (RE) and other elements by anion-exchangers (Dowex 1 type) from aqueous alcoholic
solutions of nitric acid and ammonium thiocyanate was investigated. This investigation allowed the development of simple and
effective methods of americium—curium separation from frradiated plutonium. Plutonium, TPE (in a +3 oxidation state) and RE
are firmly sorbed by the anion-exchanger from 1 M HNO3 in 90% alcohol, Fe, Al and fission products Cs, Sr, Nb, Zr, and Ru pass through the column under these conditions. The RE
separation from TPE is achieved by washing the column with 0.5M NH4SCN in 80% alcohol. The column is then washed with 0.5 M HNO3 in 85% alcohol, and americium—curium separation proceeds. Use of this method for recovery of an irradiated plutonium target
containing 100 mg Pu, Am and Cm is described. 相似文献
5.
B. Kaufmann S. Souverain S. Cherkaoui P. Christen J. -L. Veuthey 《Chromatographia》2002,56(3-4):137-141
Summary A rapid analytical method has been developed for the mutual resolution of three steroidal compounds, withaferin A, iochromolide,
and withacnistin. Liquid chromatography was performed on a Chromolith analytical column (4.6 mm i.d.×50 mm), made from a cylindrical
silica rod, operated at a flow rate of 4 mL min−1 with a simple linear gradient prepared from 0.1% aqueous formic acid and 0.1% formic acid in acetonitrile. Under optimum
conditions simultaneous separation of the compounds was achieved in less than 7 min, one eighth the time required for conventional
LC separation. The overall analysis time was reduced without sacrificing chromatographic performance—essential for the resolution
of positional isomers such as iochromolide and withacnistin. The column was coupled to a single-quadrupole mass spectrometer
and the method was characterized by good performance in terms of repeatability, selectivity, linearity, and sensitivity. Detection
limits in the single-ion-monitoring mode were 0.15 μg mL−1 or below. Finally, the developed method was successfully applied to the determination of withanolides in extracts fromlochroma gesnerioides obtained by three different processes—traditional Soxhlet extraction and two faster methods, microwave-assisted extraction
and pressurized solvent extraction. 相似文献
6.
Derivatives of 1,4-dihydropyridine (DHP) still play an important role in treatment of cardiovascular diseases. Typical degradation of the DHP ring is aromatization to pyridine ring which occurs both chemically and biochemically. It is, therefore, important to have a reliable and robust analytical method for separation of DHPs from their oxidized counterparts. Separation of closely-related substances possessing similar hydrophobicity, such as DHP and its oxidized form, can be challenging on conventional alkyl-bonded sorbents. In this study, an impact of reversed-phase (RP) liquid chromatography conditions on separation of the DHP/Ox pair has been investigated. Initially, a systematic study has been performed on 33 commercial RP columns with mobile phase acetonitrile/water for separation of foridone and its corresponding oxidized form. The retention and selectivity are discussed in view of the hydrophobic-subtraction model. Best separation was found replacing conventional C18 sorbents with ones containing an embedded polar group due to polar interactions. Similarly, application of cyano columns resulted in efficient separation of analytes. Organic modifier of mobile phase (methanol vs. acetonitrile) contributed significantly to separation of foridone from its oxidized counterpart. Separation of six chemically diverse DHPs from corresponding oxidized forms was studied on seven RP columns (traditional C18 sorbent, alkyl sorbent with polar embedded group, two different aromatic phases, pentafluorophenylpropyl sorbent and sorbent with straight chain perfluorohexyl ligand). Both acetonitrile and methanol were applied as organic modifier. It was found that application of alkyl sorbent with an embedded polar group (column Zorbax Bonus RP) or cyano sorbent (column ACE CN) yields clear separation of chemically diverse DHPs from their oxidized forms. 相似文献
7.
A new on-line redox derivatization technique using double separation columns and one redox derivatization unit was presented for enhancement of separation selectivity of HPLC. This on-line redox derivatization HPLC system consisted of two separation columns and one redox derivatization unit placed between them. The redox reaction proceeds in the derivatization unit so that an analyte compound migrates as its original form in the first column, while as its oxidized or reduced form in the second column. The retention of the analytes is controlled by the lengths of the two separation columns in this system. We adopted a small column packed with porous graphitic carbon (PGC) as a redox derivatization unit and two C18 silica columns treated with hexadecyltrimethylammonium chloride as separation columns. The redox activity of PGC and the efficiency of the on-line redox derivatization HPLC system for enhancement of separation selectivity were investigated using EDTA complexes of some metal ions. Original untreated PGC and PGC treated with hydrogen peroxide completely oxidized Co(II)-EDTA and converted it to Co(III)-EDTA, while the other metal complexes eluted as their original oxidation states throughout the system. Selective separation and determination of cobalt in a reference copper alloy by the developed method were demonstrated. 相似文献
8.
本文用苯异硫氰酸酯作柱前衍生化试剂,衍生的硒蛋氨酸及其它非硒代氨基酸用反相高交液相色谱进行分离分析,分析表明,加无机硒培养的构菌菌丝体中含一定量的硒蛋氨酸,且这一方法广泛适于生物物质中其它硒代氨基酸的分析。 相似文献
9.
Updated estimates of the selenomethionine content of four NIST wheat reference materials have been obtained by use of a revised
gas chromatography–stable-isotope dilution mass spectrometric method. The revised method makes use of digestion with methanesulfonic
acid, which enables more complete recovery of endogenous selenomethionine than was previously achieved by overnight denaturing
treatment in 0.1 mol L−1 HCl. The NIST wheat reference materials each contain approximately 55% of their total Se content as selenomethionine. Information
about forms of Se in reference materials adds value to these materials in Se speciation studies. Estimates of selenomethionine
content are also provided for other wheat samples, including several grown under conditions of exposure to high Se levels.
These samples also contain approximately 55% of their total Se content as selenomethionine. The consistent level of 55% of
total selenium occurring in the form of selenomethionine when the total selenium content varies by a factor of 500 is suggestive
of an active mechanism of incorporation of selenium into wheat grain.
Figure Selenomethionine content of wheat samples 相似文献
10.
Retention study of inorganic and organic selenium compounds on a silica-based reversed phase column with mixed ion-pairing reagents 总被引:1,自引:0,他引:1
Summary Separation of seven inorganic and organic selenium compounds, namely selenic acid [Se(VI)], selenous acid [Se(IV)], trimethylselenonium
iodide (TMSe+), selenocystine (SeCys), selenomethionine (SeMet), selenoethionine (Seet), and selenocystamine (SeCM), has been performed
on a LiChrosorb C 18 column by using mixed ion-pair reagents; 1-butanesulfonic acid and tetramethylammonium hydroxide. Flame
atomic absorption spectrometry (FAAS) was used as an element-specific detector. The retention behaviors of selenium compounds
in terms of several chromatographic parameters, such as pH of the mobile phase, the concentrations of ion-pair reagents, and
the content of organic modifier (methanol) were investigated. It was found that the separation of both inorganic and organic
selenium compounds can be achieved within 12 min with a mobile phase of 10 mM 1-butanesulfonic acid −4 mM tetramethylammonium
hydroxide −4 mM malonic acid −0.05% methanol adjusted to pH 4.5 at a flow rate of 1.0 mL min−1. The results obtained in this study showed that the use of mixed ion-pair reagents is very useful to improve the separation
of selenium compounds. The applicability of this technique for the speciation of selenium compounds in real samples was demonstrated
by the determination of selenium compounds in a selenium nutritional supplement. The results were found to be in good agreement
with those obtained by ion-exchange HPLC-ICP-MS. 相似文献
11.
E. Roy Clark Kawther A. Al-Zubaidi H. Al-Shahristani 《Journal of Radioanalytical and Nuclear Chemistry》1980,60(1):149-158
The silica gel adsorption behaviour of zirconium, niobium, ruthenium and cerium in hydrochloric acid has been investigated
by batch and column techniques. A satisfactory radiochemical separation of zirconium and niobium from each other and from
other fission products has been achieved by a two column technique. The recommended procedure consists of sorption of all
the nuclides on a primary silica gel column. Fifteen per cent of95Nb, all of the zirconium and all of the other fission products are eluted first by washing with 5.5 M HCl. A second elution
with concentrated hydrochloric acid then recovers the95Nb (free from other products). The solution from the first elution after evaporation to 1 ml is then passed through another
silica gel column and successively washed with 0.5M HCl, 5.5M HCl and concentrated HCl to obtain three fractions—other fission
products—95Zr free from other products—95Nb free from other products, respectively. 相似文献
12.
G. R. van der Hoff R. Hoogerbrugge R. A. Baumann U. A. Th. Brinkman P. van Zoonen 《Chromatographia》2000,52(7-8):433-438
Summary Normal-phase LC (NPLC) is a powerful method for the clean-up of fatty samples in the determination of organochlorine pesticides
(OCPs). The injected sample deactivates the stationary phase and the triglyceride matrix therefore serves as a polarity modifier
in the NPLC separation. Thus, the amount of sample injected is the key to both selectivity and sensitivity in matrixmodified
LC coupled to capillary GC.
In coupled LC-GC the NPLC separation becomes particularly critical because only a limited amount of the LC eluent can be transferred
to the GC and the triglyceride matrix must be prevented from entering the GC, because it degrades the performance of the injector
and the column. In previous applications method development was seriously hampered by these boundary conditions and tedious
and lengthy trial-and-error experiments were required to determine suitable experimental conditions. In this study an empirical
model was developed that describes the NPLC separation process in terms of column dimensions and fat loadability. The output
is given as the probability of achieving successful LC-GC analysis of a particular set of analytes, thus furnishing a useful
tool for the development of new applications in the field of exposure assessment and analysis of residues of apolar compounds
in fatty samples. The limitations of current procedures—maximum transfer volumes and minimal separation—are also discussed. 相似文献
13.
Summary The influence of methanol concentration, column temperature, and column back-pressure on the enantios-electivity of the separation
of eighteen amino alcohols in supercritical-fluid chromatography has been investigated by use of statistical experimental
design. The enantioselective retention of the amino alcohols was studied using Chiralcel OD and Chiralpak AD as the chiral
stationary phases and the experimental responses obtained—retention factors (k) and selectivity factors (α)—were evaluated by use of the partial least squares algorithm. The performance of the columns
was compared and the enantioselectivity of the Chiralcel OD column was found to be superior. Almost all the racemic amino
alcohols tested were separated and separation factors as high as 4.5 were obtained by use of the Chiralcel OD column.
Experimental results from a factorial design with three centerpoints resulted in a statistical model based on linear terms
only. The first-eluted enantiomers, which, when identified, were found to be theR forms, had similar retention times, whereas the retention times of theS forms were more varied. The column temperature had a greater effect on enantioselectivity than methanol content. Changes
in the system back-pressure had no significant influence on enantioselectivity.
The results obtained from the factorial design were used to predictk and α. Differences between predicted and experimental data were less than 10%.
The effect on enantioselectivity of protolytic mobile phase additives, e. g. dimethyloctylamine, acetic acid, and trifluoroacetic
acid, and of mobile-phase flow-rate, were also studied, as was the effect of solute structure. The position of substituents
on the aromatic ring, type of alkyl group attached to the nitrogen atom, and the number of methylene groups between the stereogenic
center and the nitrogen atom all affected enantioselectivity.
The chromatographic system developed could be used to determine enantiomeric purity even if the chiral impurity eluted after
the main peak. 相似文献
14.
František Kvasnička Václav Janda Daniela Rousová Jiří Manda Lubica Kollerová 《Central European Journal of Chemistry》2005,3(1):137-145
Some oxyhalides can be found in drinking waters as inorganic disinfection byproducts. An on-line coupled capillary isotachophoresis—capillary
zone electrophoresis (CITP-CZE) method was developed for the analysis of chlorate, chlorite and bromate in water. The optimized
CITP-CZE electrolyte system consisted of the following: 10 mM—HCl+20 mM—β-Alanine (leading electrolyte), 5 mM—succinic acid
(terminating electrolyte), and 10 mM—succinic acid +5 mM—β-Alanine +0.1% HPMC (carrier electrolyte). A clear separation of
oxyhalides from other components of drinking water was achieved within 25 min. Method characteristics, i.e., linearity (0–200 ng/mL), accuracy (88–110%), intra-assay (3–5%), quantification limit (5–15 ng/mL), and detection limit
(2–5 ng/mL), were determined. Minimum labor requirements, sufficient sensitivity and low running cost are important attributes
of this method. It was found that the developed method is useful for the routine analysis of oxyhalides in water. 相似文献
15.
The effects of different columns and mobile phases on the separation of mitochondrial membrane phospholipids in rice by high-performance
liquid chromatography (HPLC) were studied. The results suggest that the main six kinds of phospholipids in the rice mitochondrial
membrane can be successfully separated within 22 min on a KR 100-SIL (250 × 4.6 mm, 5 μm) column with a mobile phase of acetonitrile-methanol-85%
phosphoric acid (100: 10: 0.8, V/V) and DAD detector (205 nm). The quantitative analysis of five important components—phospatidylinositol
(PI), phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphotidic acid (PA), and phosphatidylcloline (PC)—has been
achieved with an external standard method. The linear range is 0.005–2.00 mg/mL, the recovery ratio is 95.9–100.6%, and the
relative standard deviation is 0.32–1.24%. The study indicates that the HPLC method that has been applied to the analysis
of the trace content of biomembrane phospholipids is characterized by a satisfactory linear relationship, reproducibility,
and stability.
The text was submitted by the authors in English. 相似文献
16.
Blagoj Mitrevski Paul Wynne Philip J. Marriott 《Analytical and bioanalytical chemistry》2011,401(8):2361-2371
Multidimensional gas chromatography (MDGC), and especially its latest incarnation—comprehensive two-dimensional gas chromatography
(GC × GC)—have proved advantageous over and above classic one-dimensional gas chromatography (1D GC) in many areas of analysis
by offering improved peak capacity, often enhanced sensitivity and, especially in the case of GC × GC, the unique feature
of ‘structured’ chromatograms. This article reviews recent advances in MDGC and GC × GC in drug analysis with special focus
on ecstasy, heroin and cocaine profiling. Although 1D GC is still the method of choice for drug profiling in most laboratories
because of its simplicity and instrument availability, GC × GC is a tempting proposition for this purpose because of its ability
to generate a higher net information content. Effluent refocusing due to the modulation (compression) process, combined with
the separation on two ‘orthogonal’ columns, results in more components being well resolved and therefore being analytically
and statistically useful to the profile. The spread of the components in the two-dimensional plots is strongly dependent on
the extent of retention ‘orthogonality’ (i.e. the extent to which the two phases possess different or independent retention
mechanisms towards sample constituents) between the two columns. The benefits of ‘information-driven’ drug profiling, where
more points of reference are usually required for sample differentiation, are discussed. In addition, several limitations
in application of MDGC in drug profiling, including data acquisition rate, column temperature limit, column phase orthogonality
and chiral separation, are considered and discussed. Although the review focuses on the articles published in the last decade,
a brief chronological preview of the profiling methods used throughout the last three decades is given. 相似文献
17.
The spectrophotometric reactions of triterpene compounds with concentrated sulfuric acid, a mixture of sulfuric acid and ethanol,
and a mixture of sulfuric and acetic acids has been studied with hederagenin and its glycosides — caulosides A, C, and D,
isolated from the Far Eastern plantCaulophyllum robustum Maxim — as examples. Conditions for performing the reaction which exclude the influence of the carbohydrate components of
the glycosides from the determination of hederagenin have been suggested. The reaction with a mixture of sulfuric acid and
ethanol has been used to determine the amounts of caulosides A and C in a total preparation after their separation by the
TLC method. The relative error of the determination did not exceed 5 rel.%.
Pacific Ocean Institute of Bioorganic Chemistry, Far-Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok.
Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 643–646. September–October, 1980. 相似文献
18.
Yasumi Anan Takahiro Mikami Yoshiro Tsuji Yasumitsu Ogra 《Analytical and bioanalytical chemistry》2011,399(5):1765-1772
The distribution and metabolism of selenohomolanthionine (4,4′-selenobis[2-aminobutanoic acid], SeHLan), a newly identified
selenoamino acid in selenized Japanese pungent radish, were evaluated by administering 77Se-labeled SeHLan at a dose of 25 μg/kg body weight in rats. Exogenous 77Se of SeHLan was preferably distributed to the kidneys and remained in the intact form for up to 6 h after dosing. The accumulation
in the kidneys is one of the specific characteristics of SeHLan, differing from other selenoamino acids, such as selenomethionine
and Se-methylselenocysteine, which preferably accumulate in the pancreas. The intact form of SeHLan was detected in the serum and
kidney supernatant but not in the urine, suggesting that the amount of exogenous Se that was distributed to the kidneys was
within metabolic capacity. Indeed, the exogenous Se was converted into two urinary metabolites, Se-methylseleno-N-acetyl-galactosamine and trimethylselenonium. Exogenous Se was also detected in several selenoproteins, including selenoprotein
P and extracellular glutathione peroxidase. SeHLan is expected to be a potential supplemental source of Se because its distribution
differs from that of selenomethionine and Se-methylselenocysteine. 相似文献
19.
V. Koprda 《Journal of Radioanalytical and Nuclear Chemistry》1976,30(1):103-118
The diffusion of chlorocomplexes of some corrosion and fission products in anion exchange beads has been studied in mixed
solvent media. The effects of variables on the kinetics of the exchange process by the batch and flow technique were examined.
The strongly basic anion exchanger Dowex 2X8 in its Cl− form was used in organic solvent—water—hydrochloric acid solutions. The dependence of the exchange rate on temperature, the
viscosity of the solution, the mean resin particle diameter and the composition of the solution was studied. Film and particle
diffusion coefficients were calculated from the experimental data. The results provide valuable data for the design of separation
procedures. 相似文献
20.
Magnetic separation technology was applied in the separation of flavonoids from the licorice root in this work. Licorice flavonoids
(LF) displayed a remarkable array of biological and pharmacological activities. The magnetic adsorbents with functional —NH2 groups were synthesized by immobilization of amino-silane on the surface of the magnetic silica supports, which were prepared
by co-precipitation method. The adsorption and desorption characteristics of the magnetic adsorbents for the separation of
LF have been evaluated. The purity of an enriched extract with this method was 16.7% while the crude extract only had about
6.8% purity. Therefore, it can be concluded that these kinds of magnetic adsorbents have selectivity to the flavonoids to
some extent. The affinity selectivity of the adsorbents is based on the formation of hydrogen bonding between the —NH2 on the magnetic adsorbents and —OH, —CO on the flavonoids.
Supported by the National High Technology Research and Development Program of China (Grant No. 2002AA302211) and the National
Science Fund for Creative Research Groups of China (Grant No. 20221603) 相似文献