Search results for "Mace"

Determination of phenoxy acid herbicides in drinking waters by HPLC and solid phase extraction

1998

Abstract An HPLC procedure for determining phenoxy acid herbicides in waters is described. A LichroSpher RP select B octadecyl-silane analytical column and spectrophotometric detection at 230 nm were used. Adequate retention was achieved with a mobile phase containing MeOH/phosphate buffer 10−2 M pH 2.5/PnOH (50/42/8, v/v). The herbicides were isolated from water samples by using a single solid phase extraction procedure with C18 solid-phase columns. An enrichment factor of 500 is achieved. The coefficients of variation of the method were generally lower than 2.7% at 0.4 μg L−1 herbicide concentration levels. Recoveries ranged between 93 and 118%. The results obtained indicate that the prop…

Separation Efficiency of Two SEC Packings: Comparison of Chromatographic, Thermodynamic, and Fractal Parameters

2004

Abstract The size‐exclusion chromatographic (SEC), thermodynamic, and fractal behavior of two organic packings, named TSK‐Gel HHR and TSK‐Gel HXL, has been compared in order to assess their separation efficiency. The different experimental elution trends of five solvent/polymer systems have been evidenced through the universal calibration curves, and the existence of secondary mechanisms (such as adsorption) has been quantified by the chromatographic partition coefficient K p. From a thermodynamic point of view, the swelling and crosslinking degrees have been evaluated and compared in the two gels assayed. Moreover, the values of some fractal parameters (fractal dimension of the surface and…

Über die Verwendung von homogenen azeotropen Gemischen in der Dünnschichtchromatographie 8. Mitt.: Gaschromatographische Untersuchung einiger Fließmi…

1970

Homogene azeotrope Gemische wurden vor und nach ihrer Benutzung als Fliesmittel in der DC gaschromatographisch untersucht. Hierbei zeigte sich, das bei hohem Anteil an polaren Komponenten (> 15%) keine veranderung in der Zusammensetzung der Fliesmittel eintrat. Eine gewisse Abreicherung der polaren Komponenten war jedoch festzustellen, wenn deren Anteil klein sowie der Polaritatsunterschied der Einzelkomponenten gros war und die DC-Platten eine grosere Schichtdicke als 0,1 mm besasen. Homogeneous Azeotropic Mixtures in Thin-layer Chromatography Homogeneous azeotropic mixtures have been analyzed by gas chromatography before and after they were used as solvents in TLC. If polar components wer…

2020

In this study, the potential for correlation between disintegration and dissolution performance of enteric-coated (EC) dosage forms was investigated. Different enteric hard shell capsule formulations containing caffeine as model drug were tested for disintegration (in a compendial disintegration tester) and for dissolution in both USP type I (basket) and type II (paddle) apparatuses using different media. Overall, good correlations were obtained. This was observed for both the basket and the paddle apparatus, indicating that the use of disintegration testing as a surrogate for dissolution testing (allowed by International Conference on Harmonization (ICH) for immediate release dosage forms …

Analysis of phytosterols in foods

2006

Phytosterols are bioactive compounds, one of their most studied and outstanding properties being their cholesterol-lowering activity. This explains the growing interest in the phytosterol contents of foods as either intrinsic or added components. The different steps (extraction, saponification, clean up, chromatographic determination) of plant sterol determination are reviewed, and emphasis is placed on the methods used to assay different phytosterols in food.

Beiträge zur Extraktion von Drogen. 4. Mitt.: Selektive Extraktionseigenschaften von Lösungsmitteln

1969

Am Beispiel der getrockneten Meerzwiebel wird gezeigt, wie bei der fraktionierten Extraktion mit Losungsmitteln steigender Polaritat die gewunschten Extraktivstoffe bis zu einem gewissen Grad selektiv extrahiert werden konnen. Extraction of Vegetable Drugs With the squill as example it is shown that the components of the extractable matter can be extracted selectively up to a certain point in a fractioned extraction with solvents of increasing polarity.

Spray Freeze Dried Lyospheres® for Nasal Administration of Insulin

2021

Pharmacologically active macromolecules, such as peptides, are still a major challenge in terms of designing a delivery system for their transport across absorption barriers and at the same time provide sufficiently high long-term stability. Spray freeze dried (SFD) lyospheres® are proposed here as an alternative for the preparation of fast dissolving porous particles for nasal administration of insulin. Insulin solutions containing mannitol and polyvinylpyrrolidone complemented with permeation enhancing excipients (sodium taurocholate or cyclodextrins) were sprayed into a cooled spray tower, followed by vacuum freeze drying. Final porous particles were highly spherical and mean diameters r…

Determination of Anticonvulsant Drugs in Pharmaceutical Preparations by Micellar Liquid Chromatography

2004

A micellar liquid chromatographic method for quality control of pharmaceutical preparations (capsules, pills, tablets, injections, drops, and suppositories) containing the anticonvulsant drugs acetazolamide, carbamacepine, chlordiazepoxide, diazepam, ethosuximide, phenytoin, phenobarbital, and zopiclone has been developed. This methodology involves the use of micellar solutions of cetyltrimethylammonium bromide (CTAB) as mobile phases and UV detection. The proposed approach is rapid and reproducible. Sample preparation only requires dissolution with micellar solvent and adequate dilution with the mobile phase before injection into the chromatographic system.

Performance of Markers and the Homologous Series Method for Dead Time Estimation in Reversed-Phase Liquid Chromatography

2009

Abstract Two methods for dead time estimation (the use of markers and the homologous series mathematical method) are revised. Out of twelve assayed common markers, only KBr, KI, tartrazine, thiourea, uracil, and urea yielded retention times independent of the mobile phase composition in the range 10–90% acetonitrile, using a Zorbax Eclipse XDB−C18 column. On the other hand, the quality of the estimations provided by the homologous series method was limited by the mathematical approach and the data quality. With this method, the estimated dead time is an extrapolated value, which is severely affected by the data of the most retained compounds that act as leverage points, biasing the result. …

Determination of Lobenzarit Disodium in Human Plasma by High-Performance Liquid Chromatography

1998

Abstract A reversed-phase high performance liquid chromatographic procedure was developed for determination of lobenzarit disodium in human plasma over the range 0.5−17.5 μg/mL with diphenylamine as internal standard. Plasma samples were extracted with acetonitrile and an aliquot was injected onto a Lichrospher 100 RP-18 column with ultraviolet absorbance detection at 308 nm. Composition of the mobile phase was acetonitrile-water-glacial acetic acid (50:50:0.2 v/v/v).