Octadecylsilane Stationary Phase Research Articles

Determination of vitamin A in animal feedingstuffs by high-performance liquid chromatography. Analytical Methods Committee.

A method is given for the determination of vitamin A in animal feeds. The sample is saponified with ethanolic potassium hydroxide solution and the vitamin A extracted into light petroleum and transferred into propan-2-ol. The concentration of vitamin A in this solution is determined by HPLC using an octadecylsilane stationary phase.

Simultaneous Determination of Acetaminophen, Guaifenesin, Pseudoephedrine, Pholcodine, and Paraben Preservatives in Cough Mixture by High-Performance Liquid Chromatography

□ The separation and simultaneous determination, by highperformance liquid chromatography, of acetaminophen (I), guaifenesin (II), pseudoephedrine hydrochloride (III), and pholcodine (IV), together with a series of parabens (methyl to butyl, V–VIII) in a cough mixture, has been demonstrated using a chemically bonded octadecylsilane stationary phase with a mobile phase of methanol–water–acetic acid (45:55:2) containing the ion-pairing agent octanesulfonic acid. Retention volumes for the active ingredients were 3.8 ml, 5.4 ml, 9.4 ml, and 15.6 ml for compounds I–IV, respectively. Corrected retention volumes for the parabens [5.4 ml for methyl (V), 9.6 ml for ethyl (VI), 18.5 ml for propyl (VII), and 37.9 ml for butyl (VIII)] showed an exponential relationship with chain length of the esterifying alcohols. Excipients did not interfere with the estimation of any of the compounds, hence pretreatment of the sample was unnecessary. Average recoveries of the active ingredients and of the parabens from laboratory prepared samples were essentially 100% of theoretical with standard deviations of 1.7, 0.3, 1.5, 0.3, 0.3, 3.3, 0.7, and 2.7% for I–VIII, respectively.

A Simple Analytical Method for Niacin and Nicotinamide in Foods by High Performance Liquid Chromatography

Niacin and nicotinamide, used as color fixatives in foods, were determined separatively by high performance liquid chromatography with a UV detector at 261nm. These food additives were extracted with water from meat or meat products at room temperature, and analyzed quantitatively by using ion-ion pairing in reverse phase chromatography with octadecyl silane stationary phase and a mixed mobile phase of methanol and 5mM sodium acetate solution (pH 5) containing 1mM tetra-n-butyl ammonium hydroxide (20:100).Recoveries of the additives from beef, fish, and their products were more than 90%. The detection limits of these additives were 1mg% each, and there was no disturbance to the procedure when 10mg% was added.

Simultaneous High-pressure Liquid Chromatographic Determination of Acetaminophen, Guaifenesin, and Dextromethorphan Hydrobromide in Cough Syrup

Acetaminophen (I), guaifenesin (II), and dextromethorphan hydrobromide (III) were separated and quantitated simultaneously in cough syrup by high pressure liquid chromatography. A chemically bonded octadecylsilane stationary phase was used with a mobile phase of 45% (v/v) aqueous methanol. The mobile phase pH was stabilized to 4.2 by adding formic acid—ammonium formate buffer (∼0.4%). The internal standard was o-dinitrobenzene. Retention volumes were 4ml for I, 6ml for II, 11ml for the interfere standard, and 20ml for III. Inactive syrup components did not interfere permitting direct diluted sample injection. Results on active ingredients were essentially 100% of the claim, with standard deviations of ± 1.5, 1.2, and 2.1% for I,II,andIII, respectively.

Simultaneous Quantitation of Morphine and Paraben Preservatives in Morphine Injectables

A high-performance liquid chromatographic method for the simultaneous determination of morphine sulfate, methylparahen, and propylparaben in morphine sulfate injection was developed. A reversed-phase system, based on an octadecylsilane stationary phase, was used with a binary solvent mobile phase consisting of methanol-phosphate buffer (pH4.0) containing methanol (5%) delivered at a constant rate (0.6:0.4ml/min) using a two-pump system. The detector response at 254nm was linear with the amount injected over a wide range, allowing rapid and reproducible quantitation of each component.

Studies of open-tubular micro-capillary liquid chromatography: II. Chemically bonded octadecylsilane stationary phase

A chemically bonded octadecylsilane stationary phase was successfully prepared on the inner glass surface of a micro-capillary tube of I.D. 60 μm. Using these capillary columns of length 3–20 m, several aromatic compounds were separated completely with methanol—water or acetonitrile—water as the mobile phase at a linear velocity of 0.3–1.3 cm/sec.

High-pressure liquid chromatography of drugs : An evaluation of an octadecylsilane stationary phase

The performance of a commonly used high-pressure liquid chromatographic stationary phase, octadecylsilane, has been evaluated for 30 compounds selected as representative of a wide variety of drug substances. Chromatographic behaviour is found to be highly predictable on the basis of p K a and partition coefficient, and the stationary phase should be especially valuable for the separation of acidic and neutral drugs. For basic drugs, however, the column efficiency is poor, detracting from the overall usefulness.