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1.
F. Pérez-Giménez G. M. Antón-Fos F. J. García-March M. T. Salabert-Salvador R. A. Cercós-del-Pozo J. Jaén-Oltra 《Chromatographia》1995,41(5-6):167-174
Summary The possible relation existing between RF values obtained by thin-layer chromatography for a group of anilines with connectivity indices proposed by Kier and Hall
has been studied. Using multivariable regression the corresponding connectivity functions, selected for their respective correlation
coefficients, standard deviations, Snedecor’s F and Student’s t were obtained. Regression analysis of the connectivity functions
gives a correct prediction of the experimental elution sequence for this group of substances on silica gel stationary phases
and various mobile phases of different polarity. The corresponding random and stability studies of the different prediction
models selected were carried out, showing good stability and null randomness in all cases. 相似文献
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M. T. Salabert-Salvador F. J. García-March F. Pérez-Giménez G. M. Antón-Fos R. A. Cercós-del-Pozo J. Jaén-Oltra 《Chromatographia》1995,41(5-6):702-706
Summary A study has been made of the relationship between the RF values obtained by thin layer chromatography for a group of barbiturates and the connectivity indices proposed by Kier and
Hall. By using multivariable regression we obtained the corresponding connectivity functions, which were selected on the basis
of their respective statistics parameters. The regression analysis of the connectivity functions shows a correct prediction
of the experimental elution sequence for this group of molecules on silicagel with two mobile phases of different polarity.
The corresponding random and stability studies of the different prediction models selected were carried out, demonstrating
good stability and null randomness in all cases. The results also demonstrated that different structural features determine
the RF values in TLC of barbiturates. 相似文献
4.
Summary To characterize the retention and selectivity of separations of 23 flavonoids (aglycones and glycosides) relationships betweenR
F and modifier concentration were determined for silica and diol adsorbents (with mixtures of ethyl acetate and methanol as
mobile phases), for cyanopropyl silica (with mixtures of ethyl acetate and dichloromethane as mobile phases), for aminopropyl
silica (with mixtures of ethyl acetate, methanol and water as mobile phases) and for octadecyl silica (with mixtures of methanol
and water as mobile phases). Owing to large polarity differences between aglycones and glycosides, these groups of compounds
cannot be separated other than by use of reversed-phase systems, for which the selectivity is lower. It follows from correlation
plots ofR
F1 againstR
F2 that for some pairs of adsorbents (e. g. silica and diol) selectivity differences are small; for others the points in the
plot are widely dispersed, indicating selectivity differences. The chemometric database obtained can be used to choose optimum
chromatographic systems for the separation of given sets of flavonoids and for planning gradient elution programs for separation
of flavonoid aglycones and glycosides in a single TLC experiment. 相似文献
5.
B. Banjanin J. Budimir N. Djonlagic A. Hadzisće M. Mazalović B. Stančić 《Chromatographia》1982,16(1):294-296
Summary The aim of this investigation was the synthesis of -aryl propionic acids which might be expected to have antiinflammatory activity. The total synthesis of -(4-benzoylphenyl)--methyl propionic acid was monitored by thin-layer chromatography. The adsorption of the compounds of interest was found to be dependent upon the polarity of the eluting solvents. The observed retentions were mathematicaly analysed, and the system that showed the best separation of reactants evaluated. A least squares method was used to determine the best geometric curve expressing the relationship between values for Rf and eluent composition.Presented at the 14th International Symposium on Chromatography London, September, 1982 相似文献
6.
Summary A method is reported for the separation of 16 closely related 2-(1, 2-diphenylvinyl)-3-phenylbenzofuran and 2-(1, 2-diphenylvinyl)-1-phenylnaphtho[2,1-b] furan derivatives on thin-layers of silica gel-G. 相似文献
7.
Summary 166 data sets of different chromatographic parameters for barbiturates taken from the literature were correlated with the first order valence connectivity indices. The most significant correlations were found for HPLC. The correlations depend on the structure of the substituents and the substitution mode of the barbituric acid ring.Preliminary results of this work have been published at the Annual Meeting of the Polish Chemical Society, in Krakow, September 17–20, 1980. 相似文献
8.
Miao Zhan Hongxia Jiang Xuehai Pang Tao Zhang Ruixue Xu Lifeng Zhao Yu Liu Yu Gong Yuanwei Chen 《Tetrahedron letters》2014
A highly effective and operationally practical method for the regioselective deuteration of N-alkyl-substituted anilines employing Ru3(CO)12 (?1 mol %) as catalyst and D2O as deuterium source was described. A variety of N-alkyl-substituted anilines were efficiently deuterated (up to 98%) at the ortho and/or para position with respect to the nitrogen at neutral conditions. Under the present conditions, deuterated anilines can be easily obtained with simple extraction and evaporation. Substituents with aromatic methoxy groups would not influence the selectivity compared to previous method. 相似文献
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Summary The thin-layer chromatographic behaviour of 28 phenolic compounds was studied on semicrystalline stannic tungstate layers using various solvent systems of which formic acid and n-butanol-formic acid were found to be the most useful for the separation of these compounds. Dimethyl sulphoxide was found to act as a self detector for a number of phenols. An interesting feature of the study of phenols using stannic tungstate is the novel separation of different isomeric compounds. A number of binary, ternary and quarternary separations of bioanalytical and immunophysiological importance have been achieved. 相似文献
11.
Summary Thin-layer chromatographic behaviour of thirteen anions on plain silica gel and silica gel impregnated with copper sulphate
solution has been investigated in aqueous-organic solvents containing acetone, some of which have achieved reliable and reproducible
separations. The effect of copper sulphate concentration on the mobility of anions has been examined. The results obtained
on plain silica gel have been compared with those obtained on copper sulphate impregnated layers. The impregnated layers dramatically
change the selectivity and permit separations not possible on untreated silica. Aqueous sodium chloride-acetone (9∶1) and
ammonium hydroxide-acetone (9∶1) were the most effective solvent systems for differential migration of anions. Better results
in terms of clarity of detection and compactness of spots were found with HCOOH-acetone as compared to HCl-acetone.
The effect of anion loading on RF values has been investigated and identification limits on impregnated layers determined. 相似文献
12.
Summary The previously described analytical method for carbohydrates, catecholamines, uric acid, creatine and creatinine using thin-layer
chromatography on aminomodified HPTLC plates and subsequent thermal activation of the chromatogram zones is expanded to include
several steroid hormones. Specifically, they are the pharmacologically relevant compounds cortisone and hydrocortisone, estradiol
and estradiol benzoate, estriol, estrone, methyltestosterone, testosterone and testosterone propionate, prednisolone, pregnandiol
and triol, progesterone and Reichstein's S. 相似文献
13.
Summary Surface-enhanced Raman spectra (SERS) ofp-dimethylaminobenzylidenerhodanine have been recorded on silica gel 60 F254 and Si60 F254 Raman TLC plates. Spectra were enhanced by use of a silver sol prepared according to the modified Lee-Meisel procedure. The
standard deviations of the intensities and the band ratios for the seven most intense peaks were calculated for 30 parallel
measurements. Although the Raman plate gives more reproducible results, several experimental difficulties are encountered
in the development of chromatograms.
SERS detection of ascorbigen and 1′-methylascorbigen was performed after chromatography on silica gel 60 F254 TLC and HPTLC plates and on Si60 F254 Raman TLC plates. Traditional development was used for the silica gel 60 F254 TLC plates and Si60 F254 Raman plates, and the personal OPLC technique for the silica gel 60 F254 HPTLC plates. It was found that the SERS spectrum gave information about the indole ring only. Because bonding of the analyte
to the stationary phase results in a change in molecular conformation-in contrast with the behaviour of rhodanine-the type
of the plateused and the development procedure employed can significantly influence the quality of the SERS spectrum.
Presented at Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary September 1–3, 1999 相似文献
14.
Summary Twenty barbituric acid derivatives having four different types of substitution were separated in TLC-S chambers. Using non-polar adsorbents (silanized silica gel or silica gel coated with paraffin oil) and binary water-organic solvent mixtures as the mobile phase. Linear relationships between RM and the concentration of the organic solvent were observed for the majority of the investigated compounds. The non-polar absorbents ensure a better separation than untreated silica gel especially for the therapeutically useful C5 disubstituted barbiturates. The results can be used for the optimization of the systems for the chromatography of barbiturates. The Rf values were correlated with the number of carbon atoms of the substitutions, molecular connectivity and a parameter associated with the molecular volume. The best correlations were obtained for this last parameter. 相似文献
15.
Summary Rf values of twenty therapeutic sulfonamides have been estimated in seven solvent systems. Based on these data a simple identification scheme was developed demanding only three solvent systems for complete separation.Quantification of corresponding fluorescamine derivatives at nanogram level was performed by the use of an TLC-scanner configured online with a microcomputer. Mathematical treatment of standard curves using the computer program Curve Fitter are discussed. Validity and reproducibility of results are compared with data obtained by HPLC and show good correlation. 相似文献
16.
Qing Liu Shuchen Yu Liangzhen Hu Muhamad Ijaz Hussain Xiaohui Zhang Yan Xiong 《Tetrahedron》2018,74(50):7209-7217
The cross-dehydrogenative coupling strategy for metal-free phosphonation and cyanation of secondary N-alkyl anilines has been developed firstly under mild reaction conditions. Based on detailed optimization of reaction conditions, the substrate generality of N-alkyl anilines and various hydrogen phosphonates has been investigated, and a series of versatile α-aminophosphonates and α-aminonitriles were therefore furnished in good to excellent yields. A plausible collective reaction mechanism through dehydrogenation to imine formation, then to respective α-aminophosphonates and α-aminonitriles was proposed. 相似文献
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Summary The 2-benzoylbenzoic acid series was investigated by reversed-phase, high-performance, thin-layer and column chromatography using various alkylammonium salts and di(2-ethylhexyl)orthophosphoric acid as polar associating reagents. The effects of the individual substituents on retention were quantified by log k and RM values. The compounds investigated differing in molecular structure (hydrophilic and hydrophobic substituents) commonly occurring groups in drugs and biologically active substances provide information on molecular interaction in these ion-pair systems. The combined effects on retention of organic modifier and ion-pair reagent concentration were investigated. 相似文献
19.
Similarities and differences between the retention characteristics of octadecylsilica wettable with water used in TLC and RP-18 used in HPLC have been elucidated by use of the linear relationships between log k and RM. The stationary phases compared were investigated with the same mobile phases—binary mixtures of methanol and water, acetonitrile and water, and tetrahydrofuran and water. For these adsorbents of the same type but differing in specific surface area the correlation line was shifted by log (systemI/systemII). High values of the correlation coefficients obtained over the whole range of mobile phase organic modifier concentration examined indicated that the TLC systems could be used to predict HPLC conditions for flavonoid separation. 相似文献
20.
Summary Using methanol-water mixtures as the mobile phases, the retention behaviors of thirty-seven pesticides were determined in
RP-HPLC and RP-HPTLC. Regular retention behavior was observed for all the investigated pesticides: theirR
m and logk values decreasing linearly with increasing concentration of methanol in the mobile phase. The lipophilicity and specific
hydrophobic surface area values for each compound were obtained and they have a good linear relationship. Although the chemical
structures of these pesticides were different, factor analysis proved that the lipophilicity and specific hydrophobic surface
area of these compounds have much in common, and the insecticides, fungicides and herbicides could not be distinguished from
each other according to their lipophilicity parameters obtained from chromatography method. 相似文献