Porous Silica Microparticles Research Articles

Gas chromatography on 10 um silica particles

Porous silica microparticles designed for modern liquid chromatography have proven effective in gas chromatography. Columns of 35–50 cm gave plate heights as low as 3.3 particle diameters and speeds of 2400 theoretical plates per second or 500 effective theoretical plates per second. Inlet pressures up to 70 atmospheres were required using hydrogen as carrier gas. The particles as received were too retentive for fast chromatography and gave asymmetric peaks. A coating of fluorosilicone oil overcame both problems. Other coatings were less effective. Bonded phases proved less satisfactory on both counts and also gave substantially less efficient columns and greater flow resistance. Column efficiency and flow resistance were sharply dependent on physical properties of the particles. The most efficient packing was clearly spherical particles of 5–10 μm diameter with narrow size distribution, pore diamters about 50 nm, BET surface areas of 25–50 m2/g and surfaces modified with trifluoropropyl silicone. A six-component hydrocarbon sample was separated in 33 s with a resolution of 4 for the most difficult pair and in 2.6 s with a minimal resolution. Performance was limited by end effects and by available pressure so that much better performance can be expected from longer columns and higher pressures.

Disposition of procainamide and its N-acetylated metabolite after acute I.V. Infusion in man determined by high-speed liquid chromatography

A simple and sensitive method for determination of procainamide and its N-acetylated metabolite in plasma and urine has been developed. After extraction from alkalified biological samples the amines are separated by liquid chromatography on microporous silica particles and quantified by UV-detection. Concentrations down to 0.4 nmol/ml (100 ng/ml) of plasma can be determined but the sensitivity can be increased to 0.04 nmol/ml by concentration of the extract before injection.

Étude de la pénimocycline par chromatographie en phase liquide à haute performance

High-performance liquid chromatography of penimocycline Penimocycline is an antibiotic obtained by Mannich reaction between tetracycline and ampicilline. Separation of penimocycline from tetracyclines and other impurities has been studied by high-performance liquid chromatography. The most effective method is liquid-liquid partition on a Micropak CH column (non-polar hydrocarbon bonded on porous silica microparticles) and gradient elution with water-methanol, 0.02 M phosphate buffer (pH 7.6) and 1 m M EDTA. Some results on hydrolysis of penimocycline are given.

Séparation par chromatographie en phase liquide rapide des dérivés phénylthiohydantoine des amino-acides rencontrés lors de la dégradation d'Edman

Separation by high-performance liquid chromatography of phenylthiohydantoin derivatives of amino acids released by Edman degradation The separation by high-performance liquid chromatography of seventeen phenylthiohydantoin derivatives of amino acids released after Edman degradation of proteins is described. Sixteen phenylthiohydantoin derivatives of amino acids are differentiated within 40 min by liquid-liquid partition on a column packed with Micropak CN (moderately polar alkyl nitrile phase bonded on 10-μm porous silica microparticles) and gradient elution with hexane-methylene chloride-isopropanol mixtures.