Quantitative determination of carbohydrates and some of their derivatives by direct densitometry of paper and thin-layer chromatograms

Conclusions The direct densitometric determination of mono-, di-, and trisaccharides, methyl ethers and methyl-glycosides of sugars, sugar alcohols, and acids on paper and thin-layer chromatograms was studied.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1473–1476, July, 1970.     

Simultaneous determination of light rare earths in monazite sand by densitometry on thin-layer chromatograms

The determination of individual light rare-earth metals in monazite sand is described, based on TLC with a mixture of di-isopropyl ether, diethyl ether, di(2-ethylhexyl)phosphate and nitric acid (8:8:0.4:0.07 v v ) as eluent. Linear densitometric calibration graphs are obtained for individual light rare-earths in the range 0.015-0.60 mug. The minimum detectable quantities of La. Ce, Pr, Nd and Sm are 9, 10, 20, 13 and 12 ng, respectively. The relative standard deviations for the determination of La, Ce, Pr, Nd and Sm in monazite sand were 1.8, 1.1, 5.9, 1.9 and 6.5%, respectively. Results were in good agreement with those obtained by spectrophotometry.     

Quantitative evaluation of thin-layer chromatograms

A commercially available scanning photometer, designed to scan paper electrophoresis strips, has been used to evaluate thinlayer chromatograms. The chromatogram may be lifted off the glass plate with cellophane tape which is then cut into strips and scanned, or the thin-layer chromatogram may be photographed and the photograph scanned. Newly developed cellulose-backed thin layers of silica or alumina may also be cut into strips and scanned. The instrument has also been modified to scan glass plates. A correction is applied for non-uniformity of the thin layer. Zones containing colourless components can be located by means of an auxiliary chromatogram, and the components present determined by carbon analysis.     

Glycosylation of triterpenoids of the dammarane series. VIII. Dammarane hydroxyketone β-D-glycopyranosides

Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, USSR Academy of Sciences, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 307–308. March–April, 1988.     

Quantitative estimation of salicylic acid and its metabolites by thin-layer densitometry

A rapid thin-layer densitometric method for the quantitative determination of salicylic acid and its metabolites in urine or plasma is described. The method is specific and very sensitive. Nanogram quantities of salicylic acid and its metabolites, both free and conjugated, may be estimated. Known metabolites, as well as the newly described gentisuric acid, were estimated quantitatively in urine from a patient treated with aspirin.     

Separation and micro determination of lipids by thin-layer chromatography followed by densitometry

Summary A method is presented for the rapid analysis of mixtures of lipids, particularly those from blood serum. The lipids are separated by thin-layer chromatography on silicagel, then charred with 10% aqueous sulphuric acid and the amount of carbon on the slides is measured densitometrically. 5–10 g of lipid mixture are needed for determination of the relative amounts of free sterol, sterol esters, glycerol esters, free fatty acids and total phospholipids.

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Zusammenfassung Es wird eine Methode beschrieben zur schnellen Analyse von Lipidgemischen, insbesonders von Lipiden aus Blutserum. 5–10 g eines Gemisches werden mit Hilfe der Dünnschicht-Chromatographie auf Kieselgel in Sterinester, Glycerinester, freie Steroide, unveresterte Fettsäuren und Phospholipide getrennt. Nach Verkohlung durch Erhitzen mit 10%iger Schwefelsäure werden die verschiedenen Typen densitometrisch bestimmt.

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The investigation forms part of a study on the chemical aspects of atherosclerosis, carried out under the auspices of the Netherlands Organisation of Health Research TNO.     

Quantitative analysis of phenobarbital in dosage form by thin-layer chromatography combined with densitometry

In this paper, a high-performance thin-layer chromatography (HPTLC) method combined with densitometry has been described. Chromatography was performed on silica gel Si 60F254 plates using dichloromethane-ethyl acetate-formic acid (9.5 +/- 0.5 +/- 0.1, v/v) mobile phase. This method has been successfully applied for the determination of phenobarbital in pharmaceuticals. Obtained results were comparable with traditionally used column high-performance liquid chromatography (HPLC) methods. For the proposed procedure, linearity (r > 0.999), sensitivity (limit of detection 0.4 microg/spot), recovery (97.8-102.1%), and repeatability were found to be satisfactory. The HPTLC-densitometry method has many advantages, such as simplicity, reasonable sensitivity, rapidity, and low cost, and it can be successfully used in routine quality control of multidrug preparations containing barbiturates.