Quantitative Thin-layer Chromatography Research Articles

Application of quantitative thin-layer chromatography in drug assay and stability testing : Determination of codeine phosphate, noscapine, diphenhydramine hydrochloride, phenylephrine hydrochloride, caffeine, etofyllin, phenobarbital and thiamine hydrochloride by in situ reflectance spectroscopy

The application of quantitative thin-layer chromatography involving scanning of remission in the assay of drugs in pharmaceutical preparations is described. The technique seems to be particularly useful in instances in which the usual analytical methods either cannot be applied or can be applied only with difficulty. Accuracy, reproducibility and the time required are discussed on the basis of the results of routine quality control tests. Possible applications of quantitative thin-layer chromatography in stability testing are also discussed.

A new fluorescence assay of trimethoprin and metabolites using quantitative thin-layer chromatography

A new assay procedure using quantitative thin-layer chromatography has been developed for trimethoprim and its four major free and conjugated metabolitres. The method is based upon the measurement of the fluorescence which develops for these compounds on non-fluorescing silica gel plates. Quantities as low as 0.03 μg can be determined. Previously reported assay procedures for trimethoprim have not been generally applicable for the assay of the metabolites. Accuracy and reproducibility data are reported for the determination of trimethoprim in urine, plasma and various tissues, and for the metabolites from urine.

Separation of rauwolfia alkaloids by thin-layer chromatography

The separation of twelve common Rauwolfia alkaloids for quantitative thin-layer chromatography can be effected using a minimum of five solvent systems on silica gel layers. The alkaloids can be identified by chromatographic reactions reactions and ultraviolet and infrared spectrometry.

Chlorpromazine metabolism in humans. Part I

A direct scan technique employing quantitative thin-layer chromatography for color samples of chlorpromazine and its metabolites by spectro-photometric method with the use of double-beam spectrodensitometer is described. Chlorpromazine and 17 metabolites have been analyzed qualitatively and quantitatively. This method can be applied for the assay of phenothiazines in both human plasma and urine. Extraction procedures for chlorpromazine and its metabolites in blood plasma and urine are presented. Advantages and disadvantages of this technique are discussed.

Quantitative thin-layer chromatography with the use of different types of adsorbents

In quantitative thin-layer chromatography, the accuracy of measurements is highly dependent on the type of adsorbent and liquid mobile phase used. The present work was undertaken in order to establish the degree to which the type of adsorbent and the specific surface area affect the results of quantitative measurements in thin-layer chromatography. The problem was studied by separating a series of mixtures of substances with different adsorption energies and abilities to form hydrogen bonds, on different adsorbents (including silica gel) with different specific surface areas.The type of mobile phase solvent has an effect on the chromatographic parameters examined. The spots of the separated substances were examined with a densitometer. Planimetric measurements of the spots obtained were also made. It was found that the spot areas as well as the peak areas of the densitometric curves of the developed substances depend on many factors, among which the specific surface area of the adsorbents, the mobile phase, their viscosity coefficient and the migration rate of the phase on the adsorbent layer are of special importance.Generally, the areas of the spots of substances and the peak areas increase in parallel with increases in the specific surface area of the adsorbent. Some deviations from regularity are caused by some factors that are involved in the chromatographic process.

Quantitative dünnschichtchromatographie mit hilfe von reaktionsgaschromatographie

Quantitative thin-layer chromatography with the aid of reaction gas chromatographyA new method has been developed for quantitative thin-layer chromatography in which reaction gas chromatography is utilised so that substances isolated on the chromatogram are separated in a single apparatus without being removed from the support. The gaseous products of the reaction are determined by gas chromatography. The separation of organosilicon compounds is described as an example. The error in the determination is not greater than that in the densitometric method.

The binding site of retinaldehyde in cattle rhodopsin

The binding site of the chromophoric group in native rhodopsin was identified by means of a 2-fold chemical modification of this vertebrate visual pigment. More than 50 of the 52 primary amino groups (including the chromophore carrying group) present per rhodopsin molecule were amidinated with methylacetimidate. Under these conditions 70 % of the rhodopsin remained spectrally intact with a regeneration capacity of 70 %. The remaining amino groups were labeled with dansylchloride under conditions leading to removal of the chromophore. Subsequent hydrolysis and quantitative thin-layer chromatography revealed the presence of 1.4 ϵ-amino lysine groups, 0.5 ethanolamine residue and less than 0.1 serine residue per rhodopsin. In membranes illuminated prior to amidination only 0.4 ϵ-amino lysine group could afterwards be dansylated. This clearly demonstrates that in rhodopsin the chromophoric group is bound to the ϵ-amino group of a lysine residue of opsin.

Some biochemical and histochemical properties of the age pigment in the human intervertebral disc.

In the human intervertebral disc, specially in old age, areas with so-called pigment are found. The composition of this age pigment has been studied with histochemical and microchemical techniques. A special histochemical technique for the detection of masked lipids has been devised. The granules of the pigment areas appeared to be particularly rich in masked lipids. This is also true for the abundant globular structures occurring in different regions of the annulus fibrosus. Tyrosine, sulfhydryl-containing amino acids and keratosulphate were detected histochemically in the granule proteins. By chemical extraction three lipid fractions were isolated from the annulus fibrosus tissue of the disc. With quantitative thin-layer chromatography these fractions were found to contain a large amount of triglycerides. A hypothesis concerning the formation of such areas of age pigment is proposed.

The possible role of metabolites in therapeutic response to chlorpromazine treatment.

Eight male adult schizophrenic patients undergoing chronic treatment with chlorpromazine were investigated. Clinical assessments were made weekly by a psychiatrist who was unaware of the biochemical findings. Blood samples were drawn 3 h after the first daily dose and the plasma concentrations of chlorpromazine and 11 of its metabolites were assessed by a direct scan technique employing quantitative thin layer chromatography.

Quantitative Thin Layer Chromatography (with particular reference to the "Flying Spot" system of scanning) Anonymous Papers presented at Quantitative TLC Symposium held in Loughborough, England, Jan. 4, 1971. Published by Fisons Scientific Apparatus, Bishop Meadow Road, Loughborough

Journal Article Quantitative Thin Layer Chromatography (with particular reference to the “Flying Spot” system of scanning) Anonymous Papers presented at Quantitative TLC Symposium held in Loughborough, England, Jan. 4, 1971. Published by Fisons Scientific Apparatus, Bishop Meadow Road, Loughborough Get access Journal of Chromatographic Science, Volume 10, Issue 12, December 1972, Page 21A, https://doi.org/10.1093/chromsci/10.12.21A Published: 01 December 1972

Lipids in tissues of the eye: VII. Changes in concentration and composition of sphingomyelins, cholesterol esters and other lipids in aging sclera

The lipid composition of the aging human and animal sclera has been investigated by means of quantitative thin-layer chromatography and gas chromatography. In human sclera the phosphoglycerides decrease and the other lipids increase in concentration during life span. Sphingomyelin and cholesterol esters increase by a factor of 2.5 and 23, respectively, total lipids by a factor 2.6. Cholesterol linoleate contributes especially to this increase. In the senile sclera perifibrous extracellular lipid deposits are found and the picture of lipid accumulation resembles that in aging cornea and aorta and to a certain extent that in atherosclerosis. In rabbit and bovine sclera the increases in the various lipid concentrations are relatively small. Sciera contains low concentrations of neutral and acid glycosphingolipids, which were not detected to be involved in aging. Squalene was identified in human sciera and cornea by gas chromatography. Similarities between the age-dependent scleral lipid composition and the lipids of various connective tissues are discussed.

Spot Applicator for Quantitative Thin-Layer and Paper Chromatography, Suitable for Clinical Analysis

Abstract Construction and operation of a semiautomatic TLC sample-spotting applicator are described. With the apparatus, multiple samples, each as large as 2.0 ml, can be transferred to a thin-layer chromatographic plate with little or no operator attention. Replicate analyses show a relative standard deviation of 1.35-1.99% without washout; liquid holdup is no more than 3-5%, and is of no significance in the analytical accuracy. The apparatus has been found to be very suitable for quantitative (as well as qualitative) thin-layer chromatographic analysis in the clinical laboratory.

A motorized device for qualitative and quantitative thin-layer chromatography

A motorized device for qualitative and quantitative thin-layer chromatography

Lipids in tissues of the eye VI. Sphingomyelins and cholesterol esters in human sclera

The lipid composition of normal scleras of two age-groups has been analyzed by quantitative thin-layer chromatography. The older scleras contain much higher concentrations of sphingomyelin and cholesterol esters than the younger ones. The concentrations of the remaining lipids show only little differences. Lipid deposits are found extracellularly. There appear to be striking similarities between the changes with age in sclera, cornea and aorta.

Comparative metabolism of mecloqualone-2-14C in mice, rats, dogs and man

A comparative study of the metabolism of mecloqualone (I) was carried out in mice, rats, dogs and man by use of the radioactive drug, 3-(o-chlorophenyl)-2-methyl-4[3H]-quinazolinone-2-14C. It is excreted in both urine and feces almost entirely as metabolites by all the species without loss of the 14C as 14CO2. Biliary excretion was demonstrated in rats. After hydrolysis of the conjugated metabolites in the urines with β-glucuronidase, 26–45% of the 14C-labeled metabolites (depending on the species) could be extracted with benzene. The metabolites in benzene extracts were identified by a combination of methods including quantitative thin-layer chromatography, countercurrent distribution, inverse isotope dilution and, when present in a sufficient amount, direct crystallization. The metabolic pathways and metabolites are: hydroxylation of the 2-methyl, 3-(o-chlorophenyl)-2-(hydroxymethyl)-4[3H]-quinazolinone (II); hydroxylation of the quinazolinone ring in the anthranilic acid moiety, 3-(o-chlorophenyl)-6-hydroxy-2-methyl-4[3H]-quinazolinone (III); and hydroxylation of the o-chlorophenyl ring, 3-(2-chloro-4-hydroxyphenyl)-2-methyl-4[3H]-quinazolinone (IV). Compounds I, II, III and IV were excreted in the following amounts as percent of the 14C in the urine collected up to 48 hr, respectively: mice (female, Swiss) 1, 5, 10 and 6; rats (male, Wistar descendant) 1, 26, 9 and 3; dogs (male, mongrel) <0.5, 6, 2, 18; humans (male) 0.5, 4, 3 and 17. Thus, although all the identified metabolites were excreted by all the species, the phenolic metabolite (IV) is the principal one in the benzene extract of urine in man and dogs, while in rodents it is the alcohol (II). However, the phenolicmetabolites (III and IV) were a more important component in collections of rat bile.

Quantitative thin-layer chromatography of glycolipids in animal tissues

A method is described for quantitative analysis of four glycolipids in brain. The combination of a thin-layer chromatographic system, which makes the previous separation of glycolipids by column chromatography unnecessary, with the orcinol reaction carried out in the presence of silica gel, permitted a rapid and simple determination of cerebrosides, sulphatides and monogalactosyl diglyceride with as little as 50 mg of brain tissue. Somewhat modified procedure was applied for a semi-quantitative determination of glycolipids in liver.

Quantitative dünnschichtchromatographie von mutterkornalkaloiden

Quantitative thin-layer chromatography of ergot alkaloids A description is given of thin-layer chromatography for the quantitative determination of ergot alkaloids of the peptides, alkanolamide and clavine type alkaloids (ergotamine, ergometrine, chanoclavine-(I) and their mixtures). Photometric determination was carried out after extraction of the alkaloids from the adsorbents (silica gel and aluminium oxide). Three of the five elution solvents tested proved to be useful. The results have been statistically recorded. Quantitative recovery proved to be dependent on various criteria, e.g. relative mobilities and R F values of the individual alkaloids; length and width of the alkaloid bands on the chromatogram; concentration of the solution of alkaloids applied; manner of application; partly the adsorbent and numerous other factors that generally affect thin-layer chromatography. The recovery did not seem to be influenced by the type of alkaloids used, but the individual working conditions proved to be of significance.

Quantitative thin-layer chromatography of organothiophosphorus pesticides by in situ fluorimetry.

Quantitative thin-layer chromatography of organothiophosphorus pesticides by in situ fluorimetry.

Phospholipid distribution in erythrocyte and plasma of the man, cow, pig and rabbit.

The phospholipid class composition and the ratio of the amounts of two sphingomyelin fractions, supposed to have different fatty acid compositions, were determined by quantitative thin-layer chromatography on the erythrocytes and plasma of four representative mammalian species, man, pig, cow and rabbit. A remarkable species difference was confirmed on the phospholipid class compositions between bovine erythrocyte and those of three other species. The phospholipid distribution in plasma was rather relatively similar each other in these species, with the predominant presence of choline phospholipids. The ratio of two sphingomyelin fractions varied appreciably from species to species. The bovine erythrocyte gave the highest value whereas the bovine plasma gave the lowest value of the F/S fractional ratio among these four species.

Quantitative thin-layer chromatography : Assay of Drug mixtures by scanning of remission peaks

Several examples are given showing that scanning of the remission of thin-layer chromatograms may be successfully applied to the assay of drug mixtures not responsive to less complicated methods. Simultaneous assays of etofyllin and nicotinic acid, pentobarbital and cyclobarbital, as well as sodium oestrone sulphate and sodium equilin sulphate are discussed in detail. The importance of adequate spot preparation for scanning is pointed out. Figures on the accuracy and reproducibility of the procedures are given.