thiourea and diphenyl

Reversed-phase nonporous silica (RP-NPS) of 1.5 microm dp is employed to demonstrate rapid and efficient separations in packed capillary electrochromatography (CEC). Two methods for packing capillaries and two techniques to manufacture frits used to hold the packing in place are evaluated for their effect upon separation performance using polyaromatic hydrocarbons (PAHs) and polar neutral pharmaceutical compounds. Attention is given to conditioning of the packed capillaries for high efficiency separations without necessity for sodium dodecyl sulfate (SDS). Separation conditions for the nonporous materials were modified from those previously determined on porous reversed-phase silica. Feasibility for method development and validation of a parent pharmaceutical compound and related impurities in the range of 0.1-120% of a 5 mg/mL concentration was assessed and reported. An approach to improving detection sensitivity through use of large-bore capillaries is briefly discussed.

Topics: Anthracenes; Biphenyl Compounds; Chromatography, High Pressure Liquid; Electrophoresis, Capillary; Evaluation Studies as Topic; Feasibility Studies; Fluorenes; Magnetics; Naphthalenes; Pressure; Sensitivity and Specificity; Silicon Dioxide; Thiourea

Capillary columns have been packed for capillary electrochromatography (CEC) using centripetal forces. The packed columns were maintained under wet conditions or they were dried with nitrogen gas prior to forming the retaining frits. Upon fabrication of the retaining frits, the dried columns were resolvated with the mobile phase. The performance of the columns was evaluated to determine the effect of the drying step during the packing procedure. The columns submitted to the drying step showed improved separation efficiencies and stronger retention characteristics than those kept under wet conditions. The drying step allows the silica-based packing material to be better accommodated inside the capillary column. Upon solvation, the packing material "swells," resulting in a greater packing density, which allows for a stronger retention and improved separation efficiencies. The drying step led to a 13% increase in retention on columns packed with isopropanol. An increase of 15-20% in theoretical plates for the most retained compounds was also observed in such columns.

Topics: 2-Propanol; Acetone; Benzyl Alcohol; Biphenyl Compounds; Chromatography, High Pressure Liquid; Electrophoresis, Capillary; Naphthalenes; Pentanes; Solvents; Thiourea

Topics: Biphenyl Compounds; Humans; Leprosy; Thiourea

Topics: Biphenyl Compounds; Diphenhydramine; Thiourea

Topics: Biphenyl Compounds; Humans; Rosacea; Thiourea

Topics: Biphenyl Compounds; Leprosy; Nigeria; Phenylthiourea; Thiourea

Topics: Animals; Animals, Laboratory; Antitubercular Agents; Biphenyl Compounds; Thiourea; Tuberculosis