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1.
G. Theodoridis I. Papadoyannis A. Hermans-Lokkerbol R. Verpoorte 《Chromatographia》1995,41(5-6):153-160
Summary A major problem in the HPLC analysis of alkaloids is the poor peak shape and consequently low resolution, due to the interactions
of the basic alkaloids with the residual acidic silanol groups of most reversed phase materials. The performance of new packing
materials specially designed for the separation of basic compounds has been studied using mobile phases without the special
additives commonly applied in the analysis of alkaloids. Strongly basic Cinchona alkaloids were used as test compounds. Retention
characteristics and selectivities of each material were studied, after mobile phase optimisation for the column. The influence
of the major factors (nature and content of the organic modifier, pH value, salt concentration) affecting resolution was studied.
The mobile phases were chosen so that they could be used in thermospray LC-MS. The addition of salts to the mobile phase improves
separation but in general the modification of the mobile phase gave little change in selectivity. The performance of silica-based
C18 material proved superior to the polymer materials tested. 相似文献
2.
G. Theodoridis I. Papadoyannis A. Hermans-Lokkerbol R. Verpoorte 《Chromatographia》1995,41(3-4):153-160
Summary A major problem in the HPLC analysis of alkaloids is the poor peak shape and consequently low resolution, due to the interactions of the basic alkaloids with the residual acidic silanol groups of most reversed phase materials. The performance of new packing materials specially designed for the separation of basic compounds has been studied using mobile phases without the special additives commonly applied in the analysis of alkaloids. Strongly basic Cinchona alkaloids were used as test compounds. Retention characteristics and selectivities of each material were studied, after mobile phase optimisation for the column. The influence of the major factors (nature and content of the organic modifier, pH value, salt concentration) affecting resolution was studied. The mobile phases were chosen so that they could be used in thermospray LC-MS. The addition of salts to the mobile phase improves separation but in general the modification of the mobile phase gave little change in selectivity. The performance of silicabased C18 material proved superior to the polymer materials tested. 相似文献
3.
Summary Octadecyl-porous glass was prepared and used as the packing for reversed-phase high-performance liquid chromatography. A mixture
of ginsenosides, saponins of ginseng was analyzed with detection at 203 nm. Ginsenosides Rf, Rg2, Rb1, Rc, Rb2, and Rd were separated with acetonitrile-water (27.5:72.5) as the mobile phase. A well-resoluted chromatogram of ginsenosides
Ro, Rg1 and Re was also obtained with acetonitrile-water (16.5:83.5). The whole separation was achieved in 12 min with a flowrate
of 1 ml/min. Calibration curves of ginsenosides Rb1, Rc, Rb2, Rd, Rg1 and Re were linear up to 5 μg. It can be concluded that the rapid and accurate analysis of ginsenosides is possible by the
described method. 相似文献
4.
Summary A chromatographic system comprising untreated silica gel and an aqueous buffer—methanol eluent was investigated for the micropreparative
separation of the alkaloids ofChelidonium majus L. The relationship between the logarithm of the retention factorsk of the alkaloids and volume fraction of methanol at pH* 6 was linear for volume fractions in the range of 0.1 to 0.4. From this relationship it is possible to estimate the value
of the retention factor for a given alkaloid in pure buffer and then the maximum volume of alkaloid extract that can be sampled
on micropreparative column filled with silica gel. 相似文献
5.
Summary Two simple methods were developed for the simultaneous determination of six alkaloids (ephedrine, pseudoephedrine, norephedrine,
norpseudoephedrine, methylephedrine and methyl-pseudoephedrine) inEphedrae Herba by high-performance liquid chromatography. The first method was carried out by using a Cosmosil 5C18-MS column with a gradient solvent system consisting of a phosphate buffer and acetonitrile, and detection at 210 nm. The
contents of alkaloids in non-pretreated ephedra herb extracts could be determined easily in 50 min. Alternatively, the alkaloids
could be determined within 35 minutes by using a Cosmosil 5C18-MS column with an isocratic solvent system of a sodium dodecyl sulfate-acetonitrile solution. The two methods are compared
and discussed. 相似文献
6.
Summary A reversed phase HPLC method for the separation of the five major alkaloids fromPapaver somniferum L., morphine, codeine, thebaine, papaverine and noscapine, has been developed and validated. By use of a basedeactivated
silica-based stationary phase excellent peak shape was achieved for each substance. The five alkaloids were quantified by
internal standardization within 20 min and with good precision. The method is applicable to opium and to poppy straw. 相似文献
7.
Summary The chromatographic behaviour of some porphyrins and their complexes with zinc has been studied by HPLC on 150×3.9 mm and
300×3.9 mm columns packed with Nova-Pak C18 and μ-Bondapak C18, respectively, and on a microcolumn (64×2 mm) packed with Nucleosil C18. The effect of the nature and the arrangement of side substituents in the porphyrin molecules on retention is considered.
It is demonstrated that HPLC can be used for the separation ofcis-andtrans-isomers (atropisomers) of the zinc complex of 5,15-di(phenyl-2-CH3O)-3,7,13,17-tetramethyl-2,8,12,18-tetrabutylporphyrin and other porphyrins with a similar structure. The efficiency of separation
has been compared on different columns. 相似文献
8.
Summary The proportion of organic modifier and the pH of the acetonitrile-water mixtures used as mobile phases were optimized in order
to separate a group of diuretic compounds covering a wide range of physyco-chemical properties. The Linear Solvation Energy
Relationship (LSER) formalism based either on the multiparameter π*, β and α scales or the single solvent polarity parameterE
T
N
, have been used to predict their chromatographic behaviour as a function of the percentage of acetonitrile in the eluent.
Moreover, correlation established between retention and pH of the aqueous-organic mobile phases have been used to predict
the chromatographic behaviour of the diuretic compounds studied as a function of the eluent pH. Linear correlation between
a function of the eluent pH. Linear correlation between the chromatographic retention and theE
T
N
polarity parameter of mobile phases containing different percentages of organic modifier has been obtained Based on the knowledge
of the acid-base dissociation constant the relation between retention and mobile phase pH has also been linearized. These
relationship allowed an important reduction of the experimental retention data needed for developing a given separation and
a great improvement in chromatographic optimization schemes. 相似文献
9.
Summary Poppy capsules with a high alkaloid content are of great importance to the pharmaceutical industry, because approximately
35 000 tons of straw (capsule with short stem), 350 tons of straw concentrate, and 1000 tons of opium are used annually for
extraction of morphinane alkaloids.
The combined use of four different liquid chromatographic methods is proposed for determination of alkaloid content. In the
first, semi-quantitative, method screening is performed by multilayer overpressured-layer chromatography (MLOPLC) in which
142 samples are separated on silica as stationary phase within 5 s per sample. If the morphine content is >1.3% it is then
measured quantitatively by NPHPTLC (normal-phase high-performance thin-layer chromatography) combined with densitometric evaluation.
A second, quantitative, determination is always performed by means of a rapid RPHPLC (reversed-phase high-performance liquid
chromatography) method in which the separation time is less than 4 min per sample. If the difference between the alkaloid
content measured by use of the last two methods is >12% a confirmatory RPHPLC method with increased selectivity and analysis
time (15 min) must be used.
The high throughput strategy presented has been used for analysis of ca. 15 000 samples per year, per genotype. Systematic
selection, cross-breeding, and this analytical strategy with combined planar and column liquid chromatographic methods resulted
in the discovery of two new candidate cultivars with high morphine (ca. 2%) and thebaine (ca. 1.5%) content.
Presented at Balaton Symposium '01 on High-Performance Separation Methods, Siófok, Hungary, September 2–4, 2001. 相似文献
10.
Summary A new reversed-phase (RP) HPLC method has been developed and validated for the separation of the main opium alkaloids morphine,
codeine, thebaine, papaverine and noscapine on a non-porous (micropellicular) stationary phase. On this phase quantification
of the compounds by internal standardization with brucine was achieved extremely rapidly, in ca 1.5 min, only. Thus, the analysis
time for the opium alkaloids was approximately one tenth of that on porous stationary phases. Different opium samples were
investigated using non-porous and porous packings. The correlation between the results was excellent.
Presented at Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 1–3, 1999 相似文献
11.
Summary The employment of three chiral stationary phases (CSPs) obtained by derivatizing γ-mercaptopropyl-silanized silica gel with
quinine, quinidine and N-methyl-quinium iodide, for the separation of organic racemates, is presented. They are quite useful
in the resolution of alkylarylcarbinols, binaphthyl derivatives, amides and other substances of pharmaceutical interest. 相似文献
12.
Summary An efficient, reproducible and rapid high-performance liquid chromatographic method, in normal phase mode, for the analysis of the three dinitrobenzene isomers is described. The method affords good linearity for each isomer in the range 10–160 g ml–1. The total analysis time is only 10 minutes, and the method shows an accuracy of ±1.25% with a coefficient of variation from 0.30% to 2.85% for different levels of the dinitrobenzene isomers. 相似文献
13.
Summary A rapid and sensitive high performance liquid chromatographic method is described for the determination of azlocillin in serum.
This method involves a short manual protein precipitation of the sample followed by an injection into a PR 18 column for separation
and quantitation.
The mobile phase was a 22% (V/V) solution acetonitrile in phosphate buffer pH 4.8 at a flow rate of 2,5 ml/min. The spectrophotometer
detector was set at 220 nm with a sensitivity of 0.08 AUFS. 相似文献
14.
Wen‐Jing Zhao Xu‐Yan Chen Yu‐Qian Liu Ping Li Hui‐Jun Li 《Journal of separation science》2020,43(9-10):1755-1772
Alkaloids are a widespread group of basic compounds in herbal medicines and have attracted great interest due to various pharmaceutical activities and desirable druggability. Their distinctive structures make chromatographic separation fairly difficult. Peak tailing, poor resolution, and inferior column‐to‐column reproducibility are common obstacles to overcome. In order to provide a valuable reference, the methodologies and/or strategies on liquid chromatographic separation of alkaloids in herbal medicines proposed from 2012 to 2019 are thoroughly summarized. 相似文献
15.
Summary A chromatographic method has been developed for enrichment of methionine-bound sulfur in casein, for stable-isotope analysis.
Casein is precipitated from milk samples and cleaved by acid hydrolysis in 6m hydrochloric acid at 95 °C. The amino acids released are converted into theirN-acetyl derivatives by addition of acetic acid anhydride. After lyophilization,N-acetylmethionine is separated from the accompanying components on octadecylsilica by use of a gradient prepared from 0.02m formic acid and methanol. The fractions containingN-acetylmethionine are pooled and freeze dried. Procedures for hydrolysis and derivatization were optimized to furnish the
highest yields. The influence of the abundance ratio on the chromatographic separation is shown and discussed. From 1.0 g
casein 16.5 mgN-acetylmethionine were isolated. 相似文献
16.
Summary The chromatographic properties of five columns packed with phenyl-bonded phases were characterized by an approach based on
Tanaka's method for column to column comparisons in order to develop an LC analysis of partially methylated β-cyclodextrins.
The retention behaviour of β-cyclodextrin, heptakis(2,6-di-O-methyl)-β-cyclodextrin and heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin
was examined in order to evaluate the different interactions between phenyl stationary phase and this family of compound.
Chromatograms show that the residual silanol activity of the packing materials plays a beneficial role in the partially methylated
β-cyclodextrins separation process. It is concluded that knowledge of the interactions involved allows one to make a reasoned
choice of the stationary phase in order to obtain the best possible analysis of three different commercial samples of partially
methylated β-cyclodextrins. 相似文献
17.
Summary The potential of different chromatographic systems for automated, on-line analysis of amphetamine in biological fluids is
illustrated. The various systems integrate analyte purification and enrichment, separation, derivatization in different derivatization
modes witho-phthaldialdehyde (OPA) and N-acetyl-L-cysteine (NAC), and fluorimetric detection. The reliability of the systems has been
tested by analysing urine and plasma samples containing amphetamine in the 0.1–20.0 μg mL−1 range. Pre, on and post-column derivatization strategies are compared in terms of their instrumental requirements, selectivity,
sensitivity, linearity and reproducibility. 相似文献
18.
Summary The effect of the surface chemistry of bonded-phase column material containing alkyl, phenyl, cyano and amino groups on the
adsorption of pyrimidine molecules has been studied by HPLC. The dependence of the retention on the chemical structure of
the adsorbed molecules was determined. The influence of the substituents at the pyrimidine ring and their position on the
retention character is shown for various bonded phases. 相似文献
19.
Summary The internal cyclization of a new phenyldiazene liquid crystal (called A), with an activated methylene group in theortho position to the diazo linkage, has been studied. The kinetics of cyclization were studied at different temperatures and followed
by HPLC. Separations were performed on a 30 cm×0.4 cm silica column withn-heptane-tetrahydrofuran-acetonitrile, 190∶20∶5 (v/v), as mobile phase. The Van't Hoff plot (of ln reaction constantk against 1000/T) gives a mean activation energy of 101.3±2.1 kJ mol−1. The analytical properties of A and the final compound B during the decomposition were investigated by gas chromatography
on home-made glass capillary columns coated with A. The retention times of the solutes tested became constant when the B/A
ratio reached 5, which corresponds to 83% cyclization. The nematic phase of B has interesting properties enabling the separation
of the isomers of decalin, the positional isomers of diethylbenzenes and phenols, and some polyaromatic hydrocarbons and their
derivatives. 相似文献
20.
Summary Using n-heptane as eluent a direct linear correlation was found between the logk’ values of various polar test compounds and
the silanol content determined by the methyllithium method. The peak asymmetries pass through a maximum at a medium silanol
content. Peak asymmetries and logk’ values depend also on the chain length of the bonded alkyl group. A computer program was
used to classify 25 home-made RP materials, 7 commercial products and the starting silica to achieve a hierarchical classification
of them. The arrangement provides some detailed information about the presence and the effect of silanol groups.
Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984 相似文献