silicon and octadecylsilane

Topics: Air; Air Pollutants, Occupational; Dichlorvos; Environmental Monitoring; Fenitrothion; Silanes; Silicon

Using a single mini-octadecylsilane (ODS) 5-micron ultrasphere column (0.46 X 4.5 cm) and linear gradients of different solvents, all the aspects of protein structural analysis have been defined. The effectiveness of the system has been evaluated by separating the alpha and beta chains of hemoglobin and their tryptic peptides, then performing amino acid analysis and, finally, identifying the phenylthiohydantoin derivatives of amino acids.

Topics: Amino Acid Sequence; Amino Acids; Chromatography, High Pressure Liquid; Hemoglobins; o-Phthalaldehyde; Peptides; Phenylthiohydantoin; Proteins; Silanes; Silicon; Spectrophotometry, Ultraviolet; Trypsin

Topics: Chromatography, High Pressure Liquid; Silanes; Silicon

Topics: Chromatography, High Pressure Liquid; Silanes; Silicon; Triamcinolone Acetonide

The capacity factors of several penicillins and cephalosporins, as well as those of 7-aminocephalosporanic acid, 6-aminopenicillanic acid, and 7-aminodeacetoxycephalosporanic acid, were determined at pH 2.5-7.5 with different methanol concentrations in the mobile phase. The influence of ionic strength on activity factors also was studied. Some theoretical equations providing a quantitative description of the influence of the mobile phase pH on the retention of penicillins and cephalosporins by an octadecylsilyl stationary phase were established. The analysis of experimental data by a nonlinear least-squares fit to theoretically deduced equations permitted determination of the capacity factors of anionic, cationic, zwitterion, and undissociated forms of the substances studied.

Topics: Cephalosporins; Chemical Phenomena; Chemistry; Chromatography; Drug Interactions; Hydrogen-Ion Concentration; Methanol; Penicillins; Salts; Silanes; Silicon; Structure-Activity Relationship