Thin-layer Chromatographic Systems Research Articles

Aqueous urea solution promoted resolution of five-component mixture of amino acids on silica TLC plates

Summary A thin-layer chromatographic system comprising of silica gel as stationary phase and 1.0% aqueous urea solution as mobile phase (pH 7.44) has been developed for the mutual separation of five-component mixture of amino acids [lysine (RF = 0.38), histidine (RF = 0.59), leucine (R F = 0.78), alanine (R F = 0.87), and glutamic acid (0.98)]. The presence of foreign substances such as metal cations, anions, and vitamins as impurities in the sample on the separation was also examined. Thin-layer chromatographic parameters such as standard deviation (SD), ΔRF, separation factor (α), and resolution (RS) values of separated components of the mixture of these five amino acids were calculated. The limits of detection for lysine, leucine, and alanine were found to be 1.5 μg spot –1 , whereas for histidine and glutamic acid, these were 1.2 μg and 3.0 μg spot –1 , respectively. The proposed TLC system is applicable for the identification and separation of amino acids in pharmaceutical formulations.

Surfactant modified/mediated thin-layer chromatographic systems for the analysis of amino acids.

This review incorporates a large number of chromatographic systems modified by the surfactants. A large number of solvent systems and stationary phases are summarized in this paper. Three different kinds of surfactants (anionic, cationic, and nonionic) are used as modifiers for stationary phases as well as solvent systems. Surfactants are used at all the three different concentration levels (below, above, and at critical micelle concentration) where surfactants behave differently. Modifications of both stationary phases and solvent systems by surfactants produced a new generation of chromatographic systems. Microemulsion solvent systems are also incorporated in this paper. Microemulsion thin-layer chromatography is a new approach in the field of chromatography.

Preparation and evaluation of 99mTc-cefuroxime, a potential infection specific imaging agent: A reliable thin layer chromatographic system to delineate impurities from the 99mTc-antibiotic

Technetium-99m labelled cefuroxime, a second-generation cephalosporin antibiotic and potential bacteria specific infection imaging agent was evaluated. A good radiochemical purity (95%) of the labelled product was obtained after filtering the reaction mixture through a 0.22μm filter. Scintigraphy study of the purified product showed uptake in infectious lesions 45min after injection and abscess-to-muscle ratios were found to be 1.80, 1.85 and 1.88 at 45min, 1.5hr and 3hr, respectively. A versatile and reliable chromatographic technique to assess the radiochemical purity of 99mTc-cefuroxime has also been described.

99m Tc-HMPAO in Brain SPECT Imaging; Feasibility of Ultra-Utilization of the Cold kit with higher 99mTc activities - A Chromatographic Study.

Brain SPECT imaging has become one of the most interesting subjects for most specialists in nuclear medicine because of its ability to present clear and detailed data about the brain anatomy and function, allowing the specialist to obtain the greatest sensitivity and specificity for disease detection (Catafau, 2001). Technetium-99m complex of hexamethyl propylene amineoxime (HMPAO) (which is called also exametazime) is widely used as an efficient brain perfusion agent due to the ability of the primary 99mTc-HMPAO complex to penetrate the intact blood-brain barrier (BBB) which is believed to be attributed to its lipophilic property (Hung, 1994). The primary lipophilic 99mTc-HMPAO complex is inherently unstable and rapidly converts to a secondary less lipophilic complex. Retention in the brain results from the inability of the secondary complex to cross the blood-brain barrier (Ponto, 1990). Thus, we have here one more impurity ligand in addition to the 2 other persisting impurities which are the free and hydrolyzed-reduced technetium. The radiochemical purity of the 99mTc-HMPAO preparation could be recognized by using a combination of three thin layer chromatographic (TLC) systems (Tikofsky, 1993). HMPAO commercial kits are one of the most expensive materials in nuclear medicine, in addition to that; the added Tc-99m activities proposed by the commercial venders can be enough to perform only 2 patient studies per vial which is not cost effective especially in developing countries that obstacles depending on brain SPECT as a routine imaging protocol. To overcome this, there are two postulated solutions; one is to collect a larger number of patients per session which is not practical as it may take several weeks to have a good number of patients especially in small NM facilities, the other solution is to do a cold kit fractionation which is best idea allowing having secured single patient doses at different times; however, this method needs a well trained personnel to perform it. These two solutions are still not fully applicable because of the limited Tc-99m capacity of the HMPAO vial; this motivated us to study the effect of adding up to 200% of the recommended activity to one of the commercial kits which will allow us to know to which activity limit we can have a safe preparation and if we exceeds these limits what will be the produced impurities out of this, and hence, the preparation is modifiable and recoverable or not

Effect of mobile phase composition on the overall elution process in thin-layer chromatography

Summary Phenylacetone was chromatographed on alumina with mixture of toluene and 1,4-dioxane as a mobile phase in a thin-layer chromatography (TLC) system. All the chromatograms were scanned with a densitometer. It was found that for such a binary mobile phase, there is a range of stronger component concentration that gives both peaks of Gaussian shape and triangle-like shape as well. Non-Gaussian peaks of phenylacetone chromatographed on alumina with a mixture of toluene and 1,4-dioxane were observed in the case of relatively low concentration of the latter in the mobile phase. Appropriate model describing the observed retention process is suggested.

Ethylene Glycol as New Mobile Phase for Resolution of Two-Component Mixture of Cationic Surfactants on Alumina Surface

Aqueous ethylene glycol (ethane 1,2 diol) as a green mobile phase has been used for thin layer chromatographic (TLC) studies of cationic surfactants on alumina layers. Nineteen solvent systems were used to examine the mobility of the surfactants and to discover the best TLC system for the selective separation of dodecyl trimethylammonium bromide (DTAB) from multi-component mixture of other surfactants. Among the TLC systems studied, M3 (ethylene glycol: water, 8:2) was best for achieving the selective separation of DTAB from multi-component mixture of other surfactants because in this mobile phase mobility of all surfactants except DTAB were insignificant. Effect of organic additives in aqueous ethylene glycol mobile phase on the mobility of surfactants was examined. The results obtained on laboratory made alumina TLC plates and commercially available precoated alumina HPTLC plates were compared. The lower limits of detection of DTAB, CPC, CTAB, HDTAC, and TTAB were 0.02, 0.05, 0.04, 0.06, or 0.08 µg per zone respectively. The resolution of mixture of cationic surfactants was also examined in the presence metal cations as an impurity in the analyzed sample.

Application of hydrophilic interaction TLC systems for separation of highly polar glycosidic compounds from the flowers of selectedVerbascumspecies

Separation of highly polar compounds, for example, iridoids and triterpene saponins, present in natural samples is a challenging task. Because of their nonvolatility and the lack of chromophores, their analysis by means of gas chromatography or high-performance liquid chromatography (HPLC) is difficult. The use of normal as well as reversed-phase systems fails to resolve highly polar compounds that are strongly adsorbed on polar stationary phases and poorly retained on alkyl-bonded stationary phases usually used in HPLC. Because of these facts, separation has been performed in hydrophilic interaction systems by means of thin-layer chromatography (TLC). Planar chromatography offers also a possibility to use different derivatizing agents to visualize the resolved compounds. Another problem encountered in the analysis of such compounds present in plant extracts is that they occur as multicomponent mixtures. In this article, two-dimensional (2D) TLC systems were used for the resolution of compounds present in...

Screening for tertiary and quaternary alkaloids in some African Fagara species

Abstract A method has been described for the separate extraction of tertiary and quaternary alkaloids from plant material. Different thin-layer chromatographic systems have been used to separate compounds within each group of alkaloids. The methods have been applied to the screening of the barks of five Fagara species in which the presence of angoline, angolinine, skimmianine and, in some cases, 1-hydroxy-2,9,10-trimethoxy-NN-dimethylaporphinium chloride is indicated.

A novel thin-layer chromatography system for lysergide (LSD).

Journal Article A novel thin-layer chromatography system for lysergide (LSD) Get access Geraldine V Alliston, Geraldine V Alliston Laboratory of the Government Chemist, Cornwall House, Stamford Street, London S.E.1 Search for other works by this author on: Oxford Academic Google Scholar M J de Faubert Maunder, M J de Faubert Maunder Laboratory of the Government Chemist, Cornwall House, Stamford Street, London S.E.1 Search for other works by this author on: Oxford Academic Google Scholar G F Phillips G F Phillips Laboratory of the Government Chemist, Cornwall House, Stamford Street, London S.E.1 Search for other works by this author on: Oxford Academic Google Scholar Journal of Pharmacy and Pharmacology, Volume 23, Issue 7, July 1971, Pages 555–557, https://doi.org/10.1111/j.2042-7158.1971.tb08714.x Published: 12 April 2011

The relationship between thin-layer chromatographic behaviour and the stereochemistry of some heteroyohimbine alkaloids

Abstract ANUMBER of thin-layer chromatography systems have been used to distinguish and identify some indole and oxindole alkaloids isolated from various species of the genus Mitragyna (Shellard & Phillipson, 1964). It has been suggested moreover that a relationship exists between the stereochemistry of these alkaloids and their behaviour on thin-layer chromatograms (Phillipson & Shellard, 1966). Two new heteroyohimbine alkaloids, mitrajavine and hirsutine, have recently been isolated from Mitragyna species (Shellard, Beckett, Tantivatana, Phillipson & Lee, 1966) and their behaviour on thin-layers has been compared with some related alkaloids of known stereochemistry. Based on this, certain suggestions have been made about the stereochemistry of these two new alkaloids.

Separation of Some Aromatic Amino Acid Enantiomers with Pressurized Planar Electrochromatography and TLC

Influence of buffer pH, buffer concentration and ratio of methanol to acetonitrile in ternary mobile phase on migration distance of enantiomers of phenylalanine, tyrosine and DOPA in pressurized planar electrochromatography (PPEC) and thin-layer chromatography (TLC) systems is presented and compared. The applied operating variables in PPEC system more strongly influence on separation selectivity of investigated solutes than those in TLC one. Higher separation efficiency of PPEC system relative to TLC one is also demonstrated.

Two-dimensional thin-layer chromatography of selected Polygonum sp. extracts on polar-bonded stationary phases

Two-dimensional thin-layer chromatographic systems on cyano-bonded polar stationary phases were used for the separation of some phenolic compounds extracted from two species of Polygonum: Polygonum hydropiper L. and Polygonum cuspidatum L. Non-aqueous solvents were used in the first direction and aqueous solvents were used in the second direction on CN silica TLC plates. For the separation of phenolics’ standards optimal chromatographic systems were chosen from the retention data collected in one-dimensional TLC experiments by plotting graphs of R F vs. R F dependencies. Using above described method the satisfactory results of separations were obtained.

TLC separation of amino acids with a green mobile phase

Thin-layer chromatography (TLC) of fifteen amino acids was performed using silica gel and alumina impregnated with micellar solutions of cetrimide and cetylpyridinium chloride as stationary phases and aqueous solutions of dextrose as mobile phases. TLC system comprising of silica gel impregnated with micellar solution of cetrimide (5.0 mM) as stationary phase and 40% ( w/v ) aqueous solution of dextrose as mobile phase was found the most favourable for the separation of amino acids. Impregnation of silica gel with the micellar solution of cetrimide brings about a substantial change in the mobility of lysine. Separation of lysine (ketogenic) from arginine (glucogenic) is important physiologically. Surface modification of silica gel on impregnation, as indicated by FTIR and SEM studies, was responsible for improved chromatographic performance. The effect on the separation of the presence in the sample of heavy metal cations, as impurities, was examined. Limits of detection for lysine and arginine were 0.17 ...

Thin-Layer Chromatographic Specification and Separation of Cu1+, Cu2+, Ni2+, and Co2+ Cations

The M(PyDTC)(2) (M: Cu, Co, or Ni) and CuPyDTC complexes, prepared by reactions of ammonium pyrrolidinedithiocarbamate with metal nitrates, are examined for qualitative analysis, speciation, and mutual separation using thin-layer chromatography systems. These complexes and their mixtures are spotted to the activated and non-activated thin layers of silica gel 60GF(254) (Si-60GF(254)) with a 250-microm thickness. Toluene-dichloromethane mixtures (4:1, 1:1, 1:4 v/v) are used as mobile phases for running of the complexes. All of these chromatographic systems are successfully used for speciation of Cu(2+) and Cu(1+) cations. The best analytical separation for the qualitative analysis of corresponding metal cations and mutual separation of components in M(PyDTC)(2) and CuPyDTC complexes are obtained when using pure toluene-dichloromethane (1:1 v/v) on the activated layer. This study shows that it is possible to qualitatively analyze and satisfactorily separate a mixture of Cu(1+), Cu(2+), Ni(2+), and Co(2+) cations on cited chromatographic systems. These results may be also said for the adaptability or validity on column chromatography.

Synergistic Effect of Cationic-Nonionic Surfactants on Simultaneous Separation of Phenylalanine and Tyrosine

Abstract A new thin layer chromatographic system comprising of silica gel impregnated with 0.1% aqueous solution (below CMC) of nonionic surfactant Brij-35 as stationary phase and 0.1% aqueous solution (below CMC) of cationic surfactant (cetrimide) as eluent has been found most suitable for the separation of closely related amino acids (phenylalanine and tyrosine) from their mixture. Effect of substitution of Brij-35 by cetrimide and sodium cholate has been examined to assess the impact of charge of impregnant on the chromatographic behavior of analytes. The changes brought about by the impregnation in the structure and homogeneity of silica gel have been studied by scanning electron microscopy (SEM) and fourier transform infra-red spectroscopy (FTIR) techniques. Optimizations of concentration of Brij-35 and cetrimide in the stationary and mobile phases respectively and the effect of bed height on the separation have also been examined. Chromatographic parameters like ΔRF, separation factor (α) and resolution (RS) were calculated for the separation of tyrosine from phenylalanine and separation mechanism have been proposed. The limits of detection for phenylalanine and tyrosine were found to be 0.25 and 0.23 μg respectively. The proposed method studied is simple, rapid and free from the use of volatile organic solvents.

Thin-Layer Chromatographic Mobility of Aryl-Substituted Porphyrins and Their Metalloporphyrins

The migration behavior of aryl-substituted porphyrins and their metalloporphyrins with Zn(II), Ni(II), and Cu(II) were studied in high-performance thin-layer chromatography systems with silica gel and RP(18) plates using different organic mobile phases having different polarities. The (bromohydroxy)phenyl, (phenoxy)phenyl, and oxy(acetic acid)phenyl porphyrins migrated at similar rate. Chloromethylphenylporphyrin was weakly adsorbed on silica gel using either polar or nonpolar mobile phases. The mobility of metal complexes generally tends to increase in the given order of central metal ions: Zn(II) < Ni(II) < Cu(II) on silica gel. The favorable mobile phase for the separation of ligands and the metalloporphyrins is a mixture of acetonitrile-benzene.

Anionic-Nonionic Surfactants Coupled Micellar Thin-Layer Chromatography: Synergistic Effect on Simultaneous Separation of Hydrophilic Vitamins

A micellar thin-layer chromatographic system comprising of silica layer impregnated with 0.01% sodium dodecyl sulphate (SDS) as stationary phase and 0.1% aqueous solution of Cween 80 as mobile phase was identified as the most favorable system for the mutual separation of five water-soluble vitamins (folic acid, cyanocobalamin, thiamine, pyridoxine, and riboflavin). Effects of the presence of metal cations, inorganic anions, and amines as impurities was determined. The detection and dilution limits, given in parenthesis for folic acid (1 microg and 1:0.1 x 10(4)), cyanocobalamin (0.08 microg and 1:1.25 x 10(4)), thiamine (0.05 microg and 1:2.0 x 10(4)), pyridoxine (0.5 microg and 1:0.2 x 10(4)), and riboflavin (0.5 microg and 1:0.2 x 10(4)) were determined.

Simultaneous separation and identification of cyanocobalamin, thiamine, and ascorbic acid on polyoxyethylene sorbitan monooleate-impregnated silica layers with water as mobile phase

A thin-layer chromatographic system comprising a silica layer impregnated with nonionic surfactant (2% Cween 80) as stationary phase and double-distilled water as mobile phase was identified as the most favorable system for mutual separation of the water-soluble vitamins thiamine, cyanocobalamin, and ascorbic acid. The presence of inorganic anions and metal cations as impurities in the sample, the effect of different solvents of the analyte, and the effects of pH of sample and mobile phase were examined for separation of the three-component mixture. It was possible to separate microgram amounts of thiamine from milligram amounts of cyanocobalamin and vice versa. The stability of the mixture of thiamine, cyanocobalamin, and ascorbic acid; the relative standard deviation of the R F values of separated components of the mixture; and the lowest detectable amounts of the three vitamins were determined. The proposed thin-layer chromatographic method is suitable for identification and separation of thiamine, cya...

Preliminary observations on steroid metabolism in isolated epithelum of guinea pig seminal vesicle.

The metabolism of nine radioactively labeled steroids in the epithelium of the seminal vesicle of the mature guinea pig has been studied. The rapid assimilation and metabolism of these steroids demostrate the very active biochemical nature of this tissue. Based on the use of several thin-layer chromatography systems and comparison with the locations of known standards, the following have been disclosed. Testosterone was rapidly converted to dihydrostestosterone and androstanediol. The latter was the major metablolite of dihydrotestosterone and of androsterone. Androstenedione was readily converted to androstanedione, testosterone, and dihydrostestosterone, although it formed little androstanediol. Dehydroepiandrosterone was converted to small amounts of androstenediol and androstanediol. Pregnenolone was rapidly converted to an unidentified highly polar compound only. Progesterone was converted to 5alpha-pregnane-3beta-ol-20-one and its 3alpha-isomer. Dehydroepiandrosterone and progesterone were also significantly converted to unidentified highly polar compounds. The major metabolites of 17-hydroxyprogesterone co-chromatographed with standard androstanediol, testosterone, and unidentified metabolite possessing intermediate chromatographic mobility. In addition, 17-hydroxyprogesterone was converted to small amounts of compounds possessing identical Rf values as standard androstenedione and dihydrostestosterone. The identification of the products of 17-hydroxyprogesterone metabolism and their physiologic significance must await critical evaluation. Because of its homogeneity, isolated epithelium of guinea pig seminal vesicle shows promise as a tissue preparation for use in future studies that might elucidate the role(s) of individual androgens in secretory tissues of the male accessory sex organs. Our demonstration of extensive steroid interconversions in this tissue is a logical prerequisite to such studies.

How to suppress the spontaneous oscillatory in-vitro chiral conversion of α-substituted propionic acids? A thin-layer chromatographic, polarimetric, and circular dichroism study of complexation of the Cu(II) cation withl-lactic acid

Summary In our earlier investigations we showed, for the first time, with numerous practical examples that α-substituted propionic acids dissolved in the low-molecular-weight solvents are able to undergo spontaneous oscillatory in-vitro chiral conversion. In this study, we focused on attempting to suppress the spontaneous oscillatory in-vitro chiral conversion of α-substituted propionic acids using, as example, l-lactic acid dissolved in water in the presence of copper(II) cations. Our intention was to check whether the coordinate covalent bonds between copper(II) and l-lactic acid ligands prevented the latter species from oscillatory chiral conversion. To do this we stored aqueous solutions of copper(II) acetate and lactic acid in the molar ratios 1:1, 1:2, and 1:3 for a long period of time. Scrutiny of possible chiral conversion of l-lactic acid was carried out by thin-layer chromatography (TLC), polarimetry, and circular dichroism (CD) spectroscopy. Seemingly contradictory results were obtained from our investigations. From the TLC data it was apparent that chelating of copper(II) cations with l-lactic acid molecules did not result in suppression of the spontaneous oscillatory in-vitro chiral conversion of the acid. It was also established that different molar proportions of copper(II) cation and l-lactic acid molecules had somewhat different effects on the dynamics of conversion. In contrast, from polarimetric and circular dichroism studies it was apparent that when l-lactic acid is dissolved in water in the presence of copper(II) cations almost no chiral conversion is observed. Hence a final conclusion was drawn that chelating of copper(II) cations with l-lactic acid stabilizes the chiral structure of the acid in solution. Intermolecular interactions between the copper(II)-l-lactic acid complex and the silica gel stationary phase evidently affects the structure of the complex, however, most probably resulting in partial “liberation” of l-lactic acid ligands. Thus the chiral structure-stabilizing effect of copper(II) cations is apparently weakened by the TLC system and the freed l-lactic acid molecules can undergo chiral conversion.