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Planar chromatography: current status and future perspectives in pharmaceutical analysis (short review)--II. Special techniques and future perspectives in planar chromatography.

The state of the art of various special analytical planar chromatographic methods is summarized especially for forced-flow planar chromatography (FFPC), overpressured-layer chromatography (OPLC) and rotation planar chromatography (RPC) as well as for the automated multiple development (AMD) technique. The connection between analytical planar and column liquid chromatographic methods and the identification of separated compounds with chromatographic and spectroscopic data are summarized. Some aspects of future perspectives, such as parallel connected multi-layer FFPC and long distance OPLC (LD-OPLC) are given. A combination of OPLC with the AMD method is predicted as the method of the future. Strategies using FFPC techniques are suggested in the form of a flow chart.

Chemistry, Pharmaceutical↗

PubMed2005

Determination of UV-filter residues in bathing waters by liquid chromatography UV-diode array and gas chromatography-mass spectrometry after micelle mediated extraction-solvent back extraction.

A preconcentration methodology utilizing the cloud point phenomenon is described in this study for the determination of sunscreen agent residues in bathing waters by reversed phase liquid chromatography with UV detection and gas chromatography (GC) with mass spectrometric (MS) detection. The method employs the entrapment of the analytes in the micelles of the non-ionic surfactant TX-114, upon increase of the solution temperature to 60 degrees C. The analytes are either re-extracted or back extracted from the final micellar extract into appropriate organic solvents, a procedure that facilitates the direct application of the method not only with liquid chromatography but mostly importantly with gas chromatographic analysis. Ultrasonication was employed to assist the procedure and accelerate the extraction of the analytes into the solvent phase. Under the optimum experimental conditions, the method affords satisfactory recoveries in the range of 95-102% and relative standard deviation lower than 6% without interference from the presence of the surfactant. The method was successfully applied to the determination of UV filters in natural waters.

Chromatography, Liquid↗

PubMed2005

Enhanced chromatographic resolution of amine enantiomers as carbobenzyloxy derivatives in high-performance liquid chromatography and supercritical fluid chromatography.

The carbobenzyloxy (cbz) protecting group is evaluated for it's potential to enhance the resolution of chiral amine enantiomers using high-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC). A series of cbz derivatives of commercially available racemates was prepared and analyzed by enantioselective chromatography using a variety of mobile phases and polysaccharide and Pirkle-type chiral stationary phases (CSPs). The cbz-derivatized product consistently demonstrated enhanced chiral resolution under HPLC and SFC conditions. Improved selectivity and resolution combined with an automated preparative HPLC or SFC system can lead to the rapid generation of highly purified enantiomers of desirable starting materials, intermediates or final products.

Amines↗

PubMed2006

Solid-phase extraction-gas chromatography and solid-phase extraction-gas chromatography-mass spectrometry determination of corrosion inhibiting long-chain primary alkyl amines in chemical treatment of boiler water in water-steam systems of power plants.

Gas chromatography with simultaneous flame-ionization detection (FID) and a nitrogen-phosphorus detection (NPD) as well as gas chromatography-mass spectrometry (GC/MS) has been used to characterize long-chain primary alkyl amines after derivatization with trifluoroacetic anhydride (TFAA). Electron impact ionization- (EI) and negative chemical ionization (NCI) mass spectra of trifluoroacetylated derivatives of the identified tert-octadecylamines are presented for the first time. The corrosion inhibiting alkyl amines were applied in a water-steam circuit of energy systems in the power industry. Solid-phase extraction (SPE) with octadecyl bonded silica (C18) sorbents followed by gas chromatography were used for quantification of the investigated tert-octadecylamines in boiler water, superheated steam and condensate samples from the power plant. The estimated values were: 89 microg l(-1)(n = 5, RSD = 7.8%), 45 microg l(-1) (n = 5, RSD = 5.4%) and 37 microg l(-1)(n = 5, RSD = 2.3%), respectively.

Amines↗

PubMed2003

Comparison of folate quantification in foods by high-performance liquid chromatography-fluorescence detection to that by stable isotope dilution assays using high-performance liquid chromatography-tandem mass spectrometry.

A comparison study on folate quantitation was carried out between the recently developed stable isotope dilution assay using liquid chromatography-tandem mass spectrometry (LC-MS-MS) and the frequently used HPLC with fluorimetric detection (LC-FD). By applying LC-MS-MS, spinach, wheat bread, beef, and blood plasma were found to contain 159.2, 19.8, 1.2, and 5.6 microg/100 g total folates, respectively, whereas the respective quantitative data obtained by LC-FD were 95.5, 16.2, 0.7, and 6.8 microg/100 g. In all samples, LC-MS-MS revealed superior selectivity and precision and circumvented the shortcomings of conventional LC techniques, i.e., ambiguous peak assignment as well as high detection limits for 5-formyltetrahydrofolate, 10-formylfolic acid, and folic acid. The affinity chromatography columns used in this study showed excellent cleanup performance and permitted detection limits as low as 0.1, 0.5, 0.1, 0.08, and 0.1 microg/100 g for tetrahydrofolate (H(4)folate), 5-methyl-H(4)folate, 5-formyl-H(4)folate, 10-formylfolate, and pteroylglutamic acid, respectively. Thus, a 10-fold higher sensitivity compared to solid-phase anion-exchange cartridges was achieved. However, affinity chromatography columns revealed a significantly higher affinity toward the natural vitamers than to the racemic isotopomeric standards, which has to be considered when applying the latter in stable isotope dilution assays.

Animals↗

PubMed1988

Separation of lipids by new thin-layer chromatography and overpressured thin-layer chromatography methods.

New methods were developed for the separation of major lipid classes varying in polarity from cholesterol esters to lysophosphatidylcholine. The methods were used for the analysis of extracts obtained from human sera. The lipids were separated by overpressured thin-layer chromatography, classical thin-layer chromatography, and one-dimensional thin layer chromatography, using six different solvent systems for development. These techniques are also suitable to separate unsaturated and saturated cholesterol esters according to the number of carbon atoms and double bond numbers of their constituent fatty acids.

Cholesterol Esters↗

PubMed1988

Combined lectin-affinity and metal-interaction chromatography for the separation of glycophorins by high-performance liquid chromatography.

Human erythrocyte sialoglycoproteins, or glycophorins, were chromatographed by lectin-affinity and metal-interaction chromatography on high-performance liquid chromatographic columns. Glycophorins A, B and C were separated from other proteins and from glycophorin E by using a column containing wheat germ agglutinin, immobilized on a microparticulate silica support. The glycophorins were adsorbed on the lectin column from a mobile phase containing 0.25 M sodium chloride and recovered by stepwise desorption with 0.2 M N-acetylglucosamine solution. Glycophorins A, B and C were separated into the individual components on a silica-bound iminodiacetic acid stationary phase in the copper(II) chelate form. The separation of the glycophorins by metal-interaction chromatography was accomplished by decreasing salt gradient elution. Retention times and resolution of the individual glycophorins were sensitive to the initial sodium chloride concentration and the pH of the eluent. Addition of methanol to the eluent increased the resolution. The effects of linear, decreasing gradients of pH and methanol in 25 mM phosphate buffer on the resolution of glycophorins were also investigated. In both types of chromatography the mobile phases contained 0.05% (w/v) sodium dodecyl sulfate. With octylglycoside or CHAPS in the eluent glycophorins A and C could not be eluted. Sodium dodecyl sulfate polyacrylamide gel electrophoresis was used to analyze all the chromatographic results.

Chromatography, Affinity↗

PubMed1979

Simultaneous microdetermination of capsaicin and its four analogues by using high-performance liquid chromatography and gas chromatography--mass spectrometry.

An improved method is described for the simultaneous determination of capsaicin and its analogues at levels from nanograms to micrograms using high-performance liquid chromatography (HPLC) and gas chromatography--mass spectrometry. This method consists of two steps: firstly, purification and determination of total capsaicinoid by HPLC, and secondly, the simultaneous determination of capsaicin and its analogues by mass chromatography (MC) or mass fragmentography (MF). Crude extracts of capsaicinoid were purified with a Zorbax SIL column. Total capsaicinoid was detected at 235 nm and measured automatically by a microcomputer. It was collected, evaporated, trimethylsilylated and subjected to MC or MF. After monitoring the molecular ions of trimethylsilyl derivatives of capsaicinoid and the internal standard, the absolute contents of each analogue were determined by computer. By using this method, capsaicin and all of its analogues can be determined simultaneously at levels from micrograms to nanograms without any interferences from other components.

Capsaicin↗

PubMed1989

Determination by coupled high-performance liquid chromatography-gas chromatography of the beta-blocker levomoprolol in plasma following ophthalmic administration.

Levomoprolol is a beta-blocking agent used in the topical treatment of glaucoma. The necessity for comparing the plasma levels of a drug administered by the ophthalmic route with those obtained following systemic treatment requires increasingly sensitive methods in order to determine the low plasma concentrations produced by the administration of eye drops. On-line high-performance liquid chromatography-gas chromatography and concurrent solvent evaporation proved to be advantageous in the determination of levomoprolol in human plasma. Levomoprolol was determined by capillary gas chromatography (GC) with electron-capture detection (ECD) after solid-phase extraction from plasma and derivatization. Quantitation was based on the internal standard method. The detection limit of 0.2 ng/ml is 50 times lower than that obtained with previous GC methods involving on-column injection and ECD.

Adrenergic beta-Antagonists↗

PubMed1983

On-line high-performance liquid affinity chromatography-high-performance liquid chromatography analysis of monomeric ribonucleoside compounds in biological fluids.

We describe an on-line multi-dimensional column chromatography system. It consists of a high-performance liquid affinity chromatography perfractionation column for cis-diol compounds and a series-connected reversed-phase high-performance liquid chromatography system for the analysis of ribonucleosides. This on-line procedure allows the rapid and direct analysis of methylated ribonucleic acid catabolites in biological fluids (serum, urine) and therefore might be useful in pathobiochemistry.

Chemical Phenomena↗

PubMed1989

Advances in the use of computerized gas chromatography-mass spectrometry and high-performance liquid chromatography with rapid scanning detection for clinical diagnosis.

A multi-component analytical system designed for the diagnosis of metabolic disorders is described. The urinary components are separated by a variety of chromatographic techniques, including automated amino acid analysis, high-performance liquid chromatography with diode-array detection and gas chromatography-mass spectrometry with a computerized mass spectral library search for identification of organic acids. The complete system can be used to diagnose over 100 different metabolic diseases. The usefulness of the chromatographic system is exemplified by the pre- and postnatal diagnosis of glutaric aciduria type I, the diagnosis of lysinuric protein intolerance and of alkaptonuria. Drugs and diet may cause interfering metabolites, as exemplified by glycofurol, used as a solvent for intravenous drugs, and saccharin. It is predicted that chromatography and mass spectrometry will continue to be important diagnostic tools for many years ahead.

Acids↗

PubMed1987

Molecular species analysis of lysophospholipids using high-performance liquid chromatography and argentation thin-layer chromatography.

Separation of the dimethyl ester derivative of lysophosphatidic acid into component molecular species was performed. This approach permits assessment of the metabolism of species of a given lysophospholipid class in studies that employ in vivo labeling where fatty acid analysis by gas chromatography is not useful. The relative utility of argentation thin-layer chromatography compared to reversed-phase high-performance liquid chromatography in biologically relevant model systems is discussed. Separation of 1,acyl- from 2,acyl- isomers of methylated lysophosphatidic acid was accomplished as was the analysis of monoglycerides by enzymatic radioactive phosphorylation.

Autoradiography↗

PubMed1983

Comparison of carboxymethyl-cellulose cation-exchange chromatography and high-performance liquid chromatography in the purification of guinea-pig insulin from pancreatic extracts.

Guinea-pig insulin was purified from pancreatic extracts either by carboxymethyl-cellulose cation-exchange chromatography with a sodium chloride gradient or by high-performance liquid chromatography (HPLC) on octadecyl silica with mixtures of acetonitrile and phosphate buffer. HPLC proved to be superior to ion-exchange chromatography in the purification of insulin with respect both to time saving and to the purity of the product.

Animals↗

PubMed1989

Non-aqueous size-exclusion chromatography coupled on-line to reversed-phase high-performance liquid chromatography. Interface development and applications to the analysis of low-molecular-weight contaminants and additives in foods.

An interface has been developed which permits the on-line coupling of size-exclusion chromatography in tetrahydrofuran with aqueous reversed-phase high-performance liquid chromatography. The interface isolates the required size exclusion chromatography fraction and dilutes it with water to ensure reconcentration of analytes on the reversed-phase column prior to gradient elution. Operational parameters and the influence of analyte polarity have been examined in detail. A predictive system is presented for determining the applicability of the system to any analyte, based on solute retention times on an ODS phase eluted with a methanol-water gradient. The method is illustrated with examples of direct analyses of crude lipid extracts from a snack product for 2,6-di-tert.-4-methylphenol and from chocolate for dibutyl phthalate. Detection limits of ca. 0.5 mg/kg have been achieved.

Chromatography, Gel↗

PubMed1988

Hydrophobic interaction chromatography of peptides as an alternative to reversed-phase chromatography.

Hydrophobic interaction chromatography (HIC) was examined as an alternative to reversed-phase chromatography (RPC) for peptide separations by high-performance liquid chromatography. With small peptides, selectivity was similar in both modes. This was the case with commercially available standards and with a set of synthetic peptides having the same amino acid composition but different sequences. Column efficiency was higher in RPC. HIC possesses several other disadvantages, including significant baseline changes during gradient elution and a requirement for non-volatile mobile phases, which complicates peptide isolation. Thus, RPC is still the method of choice for most small peptides. Marked differences in selectivity were noted with small proteins and polypeptides large enough to possess tertiary structure. Good results were also obtained by HIC in the case of some peptides that could not be purified at all by RPC, due to aggregation or poor binding or recovery. Thus, in these cases, HIC is a useful alternative to RPC for peptide purification.

Chemical Phenomena↗

PubMed1987

Analysis of triacylglycerols by combined high-performance liquid chromatography and gas-liquid chromatography.

A method for the analysis of the triacylglycerols from animal and human adipose tissue has been developed by combining high-performance liquid chromatography and gas-liquid chromatography (HPLC) and (GLC). Following isolation by thin-layer chromatography, the triacylglycerols are chromatographed by HPLC on a 5-micron Spherisorb ODS column with a gradient of 45 to 60% 2-propanol in acetonitrile as the mobile phase. Fractions eluted from the column are collected at intervals ranging from 0.2 to 1.0 min, and the triacylglycerols present are then trans-esterified prior to analysis of the resulting fatty acid methyl esters by an automated packed column GLC system. Triacylglycerols eluted from the column may be identified by a combination of their elution volume in HPLC and their fatty acid content. From the GLC data, profiles can be constructed for the distribution of several fatty acids amongst the triacylglycerols present in the adipose tissue sample. The method can be used with solvents such as acetonitrile, 2-propanol and acetone in the mobile phase, and there is no baseline drift during gradient elution. The adipose tissue triacylglycerols of normal and streptozotocin induced diabetic rats have been compared. No differences in the distribution of the fatty acids in the two groups of rats were observed under the conditions of our study.

Adipose Tissue↗

PubMed1997

Determination of mycotoxins produced by Fusarium isolates from banana fruits by capillary gas chromatography and high-performance liquid chromatography.

A method of analysis for trichothecenes (nivalenol, deoxynivalenol, 3- and 15-acetyldeoxynivalenol, diacetoxyscirpenol, neosolaniol, T-2 tetraol, T-2 and HT-2 toxins), zearalenone and zearalenols, and another method for determination of fumonisin B1 are described and applied to cultures of Fusarium isolated from bananas. Both methods were adapted from different techniques of extraction, clean-up and determination of these mycotoxins. The first method involves extraction with methanol-1% aqueous sodium chloride, clean-up of extracts by partition with hexane and dichloromethane, additional solid reversed-phase clean-up and analysis of two eluates by both high-performance liquid chromatography with ultraviolet detection and capillary gas chromatography. The method for fumonisin B1 implies extraction with aqueous methanol, concentration, clean-up with water and methanol on Amberlite XAD-2 column, formation of a fluorescent 4-fluoro-7-nitrobenzofurazan derivative and analysis by high-performance liquid chromatography with fluorescence detection. Both procedures give good limits of detection and recoveries, and are considered suitable for the detection and quantification of the studied toxins in corn and rice cultures of Fusarium spp. isolated from banana fruits.

Carboxylic Acids↗

PubMed1982

Sample purification using a C18-bonded reversed-phase cartridge for the quantitative analysis of corticosteroids in adrenal cell cultures by high-performance liquid chromatography or gas chromatography--mass spectrometry.

Quantitative extraction and subsequent purification of small biological samples often involve cumbersome procedures. We have devised a short and efficient method for the quantitative extraction of the corticosteroid and the 20 alpha reduced steroid series from culture medium containing 20% sera in a single, pure fraction with separation from cholesterol. Passage through a C18-bonded reversed-phase Sep-Pak cartridge of the acidified culture medium and subsequent extraction of the steroid fraction with methanol yields a single fraction containing all steroids in 90% recovery and reduced quantities of cholesterol down to 30%. The extract can then be used without further purification for quantitative analysis by high-performance liquid chromatography or derivatized and analyzed by gas chromatography and gas chromatography--mass spectrometry.

Adrenal Cortex Hormones↗