sodium-dodecyl-sulfate and ethyl-acetate

New methods based on MEEKC coupling with field-amplified sample injection (FASI) induced by ACN were proposed for five isoquinoline alkaloids (berberine, palmatine, jatrorrhizine, sinomenine and homoharringtonine) in no salt and high salt sample solution (HS). For the separation of five isoquinoline alkaloids, a running buffer composed of 18 mM sodium cholate, 2.4% v/v butan-1-ol, 0.6% v/v ethyl acetate, 10% v/v (or 30% v/v) methanol and 87.0% v/v (or 67% v/v) 5 mM Na2B4O7~10 mM NaH2PO4 buffer (pH 7.5) was developed. In order to improve the sensitivity, FASI induced by ACN was applied to increase the detection sensitivity. The detection limit was found to be as low as 0.0002 microg/mL in no salt sample solution and 0.062 microg/mL in HS. The method has been applied for the analysis of human urine spiked with analytes, and the assay results were proved to be satisfactory, and also the determination of berberine in urine sample after oral administration berberine.

Topics: 1-Butanol; Acetates; Acetonitriles; Alkaloids; Berberine Alkaloids; Chromatography, Micellar Electrokinetic Capillary; Harringtonines; Homoharringtonine; Humans; Hydrogen-Ion Concentration; Methanol; Morphinans; Reproducibility of Results; Sensitivity and Specificity; Sodium Dodecyl Sulfate; Water

Detergents are commonly used for the extraction of hydrophobic proteins and must be removed for sensitive detection of peptides by mass spectrometry. We demonstrate that ethyl acetate is able to extract octylglycoside from a protease digest without loss of peptides or interference with the peptide mass spectral profile. Ethyl acetate extraction was also found to reduce interference by sodium dodecyl sulfate, Nonidet P-40, or Triton X-100 in the mass spectrometry analysis.

Topics: Acetates; Detergents; Peptides; Proteins; Sodium Dodecyl Sulfate; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Surface-Active Agents

The use of microemulsion electrokinetic chromatography was proposed to separate psoralen and isopsoralen in Psoralea corylitolia L. and its preparations. After conducting a series of optimizations, baseline separation was obtained for the analytes under the optimum conditions [sodium dodecyl sulfate 1.05% (m/v), ethyl acetate 0.96% (v/v), butan-1-ol 0.24% (v/v), 25 mm borate, pH 8.5, applied voltage 17.5 kV and detection at 254 nm]. Regression equations revealed linear relationships (correlation coefficients 0.9997 for psoralen and 0.9999 for isopsoralen) between the peak area of each analyte and the concentration. The limits of detection (defined as a signal-to-noise ratio of about 3) were 0.42 microg/mL for psoralen and 0.32 microg/mL for isopsoralen, respectively. The analytes were successfully determined with recoveries ranging from 95.50 to 102.03%. The method has been successfully applied for the analysis of psoralen and isopsoralen in medical samples. Furthermore, a simple and effective extraction method, with methanol in an ultrasonic water bath for 20 min three times, was used for sample preparation.

Topics: 1-Butanol; Acetates; Chromatography, Micellar Electrokinetic Capillary; Cross-Linking Reagents; Drugs, Chinese Herbal; Emulsions; Ficusin; Furocoumarins; Hydrogen-Ion Concentration; Intercalating Agents; Plant Structures; Plants, Medicinal; Psoralea; Reproducibility of Results; Sensitivity and Specificity; Sodium Dodecyl Sulfate

Recombinant human growth hormone (rhGH) was encapsulated within poly(D,L-lactic-co-glycolic acid) microspheres by a double emulsion solvent evaporation method. A mixture of methylene chloride and ethyl acetate in varying volume ratios was used for the microsphere preparation. Protein release profiles from three different microsphere formulations demonstrated initial burst effects ranging from 28.2% to 54.7% after a 1-day incubation and exhibited no further significant releases up to 19 days. This was because the encapsulated rhGH with the microspheres was largely aggregated in a noncovalent fashion during the formulation. Nonaggregated water soluble rhGH species within the microspheres are likely to be responsible for the rapid release upon incubation. The initially released rhGH in the incubation medium, however, was composed of mostly monomer species with a small amount of dimer as probed by size-exclusion chromatography. Circular dichroism spectra of the initially released rhGH in the medium revealed that the conformation of the released rhGH was correctly folded relative to that of native rhGH, with little variation in alpha-helix contents depending on the formulations. The "nonrelease" mechanism after the initial burst release was attributed to nonspontaneously dissociable noncovalent protein aggregation and surface adsorption of rhGH present within the microspheres.

Topics: Acetates; Adsorption; Biocompatible Materials; Chromatography, High Pressure Liquid; Circular Dichroism; Delayed-Action Preparations; Dimerization; Drug Carriers; Drug Compounding; Freeze Drying; Guanidine; Human Growth Hormone; Humans; Lactic Acid; Methylene Chloride; Microspheres; Polyesters; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Polymers; Protein Structure, Secondary; Sodium Dodecyl Sulfate; Solubility

A combination chloride electrode was used to determine quantitatively the outward rate of epidermal chloride transport in vivo. Regional anatomical variation and the effects of topical agents and cellophane tape strippings on the rate of chloride diffusion were determined. Transepidermal chloride flux through hydrated skin appears to be an alternative method for determining stratum corneum function in vivo.

Topics: Acetates; Acetone; Biological Transport; Chlorides; Dermabrasion; Dimethyl Sulfoxide; Electrodes; Humans; Skin; Sodium Dodecyl Sulfate; Sweating; Time Factors; Water