Determination of dexamethasone acetate in CETETH 20‐based in liquid crystalline systems using HPLC

2020 ◽  
Author(s):  
Márcia Helena Oyafuso ◽  
Bruno Fonseca‐Santos ◽  
Ana Carolina Kogawa ◽  
Flávia Chiva Carvalho ◽  
Maria Palmira Daflon Gremião ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Dexamethasone Acetate

Determination of the charge of Al13 Keggin oligocations intercalated into synthetic hectorite

2019 ◽  
Vol 74 (1) ◽  
pp. 85-90
Author(s):  
Marius Schöttle ◽  
Dominik Schuchardt ◽  
Andreas Edenharter ◽  
Sebastian Koch ◽  
Jürgen Senker ◽  
...  
Keyword(s):  
Reaction Time ◽  
Solid State ◽  
Ir Spectroscopy ◽  
Cation Exchange ◽  
Elemental Analysis ◽  
Crystalline Phase ◽  
Solid State Nmr ◽  
Liquid Crystalline ◽  
A Charge

AbstractApplying a nematic liquid crystalline phase of a synthetic Na-hectorite with layer separations >100 nm, the reaction time for pillaring with Al13 Keggin oligocation could be reduced to seconds ensuring that cation exchange is controlled by thermodynamics. With this material at hand we are able to resolve the long-standing dispute regarding the charge of intercalated Keggin oligocations. Micropore sizes as determined by physisorption isotherms, adsorption isotherms obtained via elemental analysis, and results of 27Al solid-state NMR and pyridine probe IR spectroscopy favor a charge of +7 for the Al13 pillars intercalated into hectorite unaltered.

Reverse Phase Liquid Chromatographic Determination of Dexamethasone Acetate and Cortisone Acetate in Bulk Drug Substances and Dosage Forms: Method Development

1987 ◽  
Vol 70 (5) ◽  
pp. 829-833
Author(s):  
Linda L Ng
Keyword(s):  
Mobile Phase ◽  
Method Development ◽  
Chromatographic Determination ◽  
Dosage Forms ◽  
Cortisone Acetate ◽  
Drug Substances ◽  
Dexamethasone Acetate ◽  
Bulk Drug ◽  
Liquid Chromatographic

Abstract The determination of the steroid acetates was evaluated for ruggedness of the method by using an octyldecylsilane column, 254 nm detection, and acetonitrile-water as mobile phase. Mobile phase pH, oven temperature, and columns from various manufacturers had no dramatic effect on the chromatography. The method was then optimized for dexamethasone acetate and cortisone acetate bulk drug and dosage forms. For dexamethasone acetate, the bulk drug substance should be dried at 105°C before use, and the sample should be dissolved in 50% acetonitrile-buffer pH 6 for stability. Cortisone acetate, on the other hand, was found to be nonhygroscopic and hence could be used as received. For stability, the sample should be stored in 50% acetonitrile-buffer pH 4

scholarly journals Identification and Quantitation of Polymyxin B, Framycetin, and Dexamethasone in an Ointment by Using Thin-Layer Chromatography with Densitometry

2005 ◽  
Vol 88 (5) ◽  
pp. 1549-1554 ◽  
Author(s):  
Jan Krzek ◽  
Anna Maślanka ◽  
Pawel Lipner
Keyword(s):  
Thin Layer ◽  
Silica Gel ◽  
Polymyxin B ◽  
Rapid Identification ◽  
Mobile Phases ◽  
Relative Standard ◽  
Dexamethasone Acetate ◽  
Similar Accuracy ◽  
Layer Chromatography

Abstract A new thin-layer chromatographic-densitometric method has been developed for rapid identification and quantitative determination of polymyxin B, framycetin, and dexamethasone in a dental ointment. Silica gel 60 and F254 silica gel 60 plates were used for separating antibiotics and dexamethasone acetate, respectively. When determining framycetin and polymyxin B, chromatograms were developed by using 2 mobile phases, namely methanol and methanol–n-butanol–ammonia (25%)–chloroform (14 + 4 + 9 + 12, v/v/v/v/). The densitometric measurements were made at 550 nm after detection with 0.3% ninhydrin solution. Dexamethasone was determined by using the mobile phase cyclohexane–ethyl acetate (2 + 3, v/v) and ultraviolet densitometric recording at 245 nm. The results obtained for individual constituents with the chromatographic-densitometric method demonstrate similar accuracy, relative standard deviation values from 1.49 to 2.47%, and relative error values from 0.02 to 0.81% and are comparable to those obtained with the reference methods.

Reverse-Phase Liquid Chromatographic Determination of Dexamethasone Acetate and Cortisone Acetate in Bulk Drug Substance and Dosage Forms: Collaborative Study

1988 ◽  
Vol 71 (3) ◽  
pp. 534-538
Author(s):  
Linda L Ng
Keyword(s):  
Dosage Forms ◽  
Cortisone Acetate ◽  
Drug Substance ◽  
Reverse Phase ◽  
Coefficients Of Variation ◽  
Dexamethasone Acetate ◽  
Phase Liquid ◽  
Bulk Drug ◽  
Liquid Chromatographic

Abstract A reverse-phase liquid chromatographic method for determination of dexamethasone acetate and of cortisone acetate was subjected to an interlaboratory study by 8 collaborators for each steroid acetate. Bulk drug substance, suspensions, and tablets were assayed. Bulk drug or dosage form is dissolved in an acetonitrile-buffer mixture and analyzed by an external standard method. The steroid acetate is resolved from extraneous components by reverse-phase chromatography and detected at 254 nm. The sample solutions are stable for at least 72 h. For dexamethasone acetate, coefficients of variation were 0.9 and <3.1% for the bulk drug substance and the suspensions, respectively. For cortisone acetate, coefficients of variation were 0.7% for bulk material, <2.0% for suspensions, and <2.5% for tablets. All dosage forms were commercial formulations. The 2 methods have been adopted official first action

scholarly journals X-Ray Diffraction Studies on Alicyclic Saturated Discotic Liquid Crystals

1987 ◽  
Vol 42 (6) ◽  
pp. 631-635 ◽  
Author(s):  
H. W. Neuling ◽  
H. Stegemeyer ◽  
K. Praefcke ◽  
B. Kohne
Keyword(s):  
Liquid Crystalline ◽  
Optical Observations ◽  
X Ray Diffraction ◽  
X Ray ◽  
Alkyl Chains ◽  
New Class ◽  
X Ray Scattering ◽  
Oriented Samples ◽  
Hexagonal Columnar

The discotic liquid crystalline phase of a new class of disc-like molecules (hexa-O-alkanoylscyllo- inositoles) is studied by small angle X-ray scattering, DSC and optical observations. Comparison of these three methods allows the determination of the structural arrangement. X-ray film exposures of oriented samples clearly demonstrate the hexagonal columnar ordered type of mesophases. A simple model calculation shows that the alkyl chains of neighbouring columns interpenetrate each other to a small extent.

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