Determination of amitriptyline and nortriptyline in human plasma by quantitative thin-layer chromatography

A thin-layer chromatographic method for simultaneous determination of amitriptyline (AT) and nortriptyline (NT) in human plasma is described. Both substances are extracted from biological material by means of a single extraction. The extract is evaporated until dry and the residue quantitatively applied to a silica gel thin-layer plate. AT and NT are separated from interfering plasma components by chromatography. The spots are visualized by nitration, reduction and coupling with N-(1-naphtyl)ethylenediamine on the plate. The intensity of the azo-dyes formed can be measured densitometrically. Using 1 ml of plasma, the sensitivity limit was 0.5 ng/ml for both substances. About 10–15 plasma samples can be analysed per day. The method is applicable to pharmacokinetic studies after a single oral dose of 25 mg AT as hydrochloride in man.     

The determination of aminoacyl adenylate by thin-layer chromatography.

A rapid and convenient method is presented by which one may determine the extent of formation of Enz·(AA ∼ AMP) in the presence of isotopic amino acid, isotopic nucleotides, tRNA, enzyme, etc. Separation of the components of the reaction mixture is achieved by chromatography on tlc cellulose. Aminoacyl adenylate separates from other solutes and is characterized by its chemical and enzymatic reactions. The method may be used to determine the equilibrium constant for the synthesis of Enz·(AA ∼ AMP) which is very sensitive to salt concentration.     

Preparative thin-layer and column chromatography of prostaglandins

Chromatographic methods are used to identify various monounsaturated PGs (prostaglandins). TLC (thin-layer chromatography) and column chromatography are described in detail. These systems were developed specifically for separating epimers of PGE1 and PGF1, but they are useful in separating some of the known natural PGs as well. A table presents information on identification of the various PGs with neutral silica and acidic silica. The results of these laboratory experiments indicate that 1 ug-1g of PG can be purified by chromatographic methods with little or no loss due to irreversible adsorption or rearrangement if proper precautions and solvent systems are used. TLC seems to be useful in distinguishing diastereomers of PGs. Relative mobilities of the various hydroxy diastereomers are not changed by the solvent systems or by esterification.     

Separation of sterol acetates by column and thin-layer argentation chromatography

Column and thin-layer chromatographic systems employing silver nitrate-impregnated adsorbents are described for the separation of sterol acetates which differ in the number of double bonds in the steroid nucleus or side chain.     

Precise discrimination among homologous sequences by DNA probe column chromatography.

Synthesized oligo probes were immobilized to a HPLC gel in high concentrations (30-40 O.D. per gram dry gel), packed in a column (2mm x 10cm) and incorporated into a conventional HPLC system. The system was applied to the discrimination among homologous sequences. Two probes different in sequence and length (16mer and 24mer) were investigated under isothermal and isocratic conditions. For each probe, 4 oligos of similar sequences, one perfectly matched to the probe and others containing one mismatch in the center of the chain, were synthesized. The chromatogram obtained as the results of high performance liquid affinity chromatography (HPLAC) considerably varied with the column temperature and the type of mismatches. The dependency of the deformation of elution profile upon mismatch seemed to reflect the stability of the hybrid composed of samples and immobilized probe.     

Qualitative and quantitative determination of sesquiterpenoids in Achillea species by reversed-phase high-performance liquid chromatography, mass-spectrometry and thin-layer chromatography

A reversed-phase high-performance liquid chromatographic method was developed as a universal analysis system in order to determine and quantify antiphlogistic sesquiterpenoids in different Achillea species. Identification was performed by HPLC and diode array detection as well as by monitoring the HPLC fractions by TLC and MS. Using santonin as internal standard, HPLC separations were achieved with a methanol–water gradient system using RP 8 LiChrospher 100 (5 μm) as stationary phase. For validation, sample analyses were performed, using the two tetraploid species A. collina and A. pratensis. The method allows the identification and quantification of the main compounds achillicin, 8α-tigloxy-artabsin, 8α-angeloxy-artabsin, arglanin and santamarin with variation coefficients between 3.4 and 4.7% (total content) using santonin as internal standard. For the different compounds recovery was found between 81 and 107% performing multiple analyses of A. collina and A. pratensis.     

Four-directional-development thin-layer chromatography of lipids using trimethyl borate

Solvent mixtures containing trimethyl borate virtually eliminated the pronounced interconversion of 1,2- and 1,3-dipalmitins during their resolution by thin-layer chromatography on Silica Gel G. With trimethyl borate, an average of 1-2% of 1,2-dipalmitin was converted to 1,3-dipalmitin. A four-directional-development TLC procedure incorporating trimethyl borate resolves cholesteryl glucoside, ceramides, monogalactosyl diglyceride, 1- and 2-monopalmitin, palmitic acid, cholesterol, 1,2- and 1,3-dipalmitin, tripalmitin, methyl palmitate, cholesteryl palmitate, beta-carotene and some of its degradation products, squalene, and tetracosane. Digalactosyl diglyceride, phosphatidic acid, phosphatidylglucose, cerebrosides, and other phospholipids remain near the origin. A mixture containing triolein, 1,2- and 1,3-diolein, 1- and 2- monoolein, oleic acid, and cholesterol was resolved in one dimension. A similar series of palmitic-containing neutral lipids was also resolvable in one dimension. These procedures were applied to the TLC of human sera lipids.     

High-performance liquid column and thin-layer chromatographic determination of human serum glibenclamide at therapeutic levels

For glibenclamide bioavailability studies in serum, high-performance liquid column and thin-layer chromatographic methods were introduced. Both methods are specific, accurate and sensitive with detection limits of at least 5 ng of glibenclamide per ml of serum. Detection is performed in the ultraviolet at wavelengths of 200 nm for liquid chromatography or 300 nm for thin-layer chromatography.Serum levels determined by either method correlated well with those determined by an already existing radioimmunoassay. Some pharmacokinetic data were computed using a one-compartment open model.     

Preparative scale separation of neutral lipids and phospholipids by centrifugally accelerated thin-layer chromatography

Mixtures of lipids and phospholipids were separated by centrifugally accelerated thin-layer chromatography on a preparative scale (300-500 mg lipid mixture per run). The isolated lipids and phospholipids were identified by 1H and 13C NMR spectroscopy and their fatty acid composition was determined by GLC and GLC-MS of their methyl esters.