RESUMO
We report the design and synthesis of a polymer structure from a cross-linkable epoxy-ionic liquid system which behaves like a hard and brittle epoxy thermoset, perfectly ductile thermoplastic and an elastomer, all depending on controllable network compositions.
RESUMO
Experimental conditions and parameters involved in high performance liquid chromatography (HPLC) separations of the peptide hormone oxytocin and seven of its diastereoisomers, namely [1-hemi-D-cystine]-, [2-D-tyrosine]-, [4-D-glutamine]-, [5-D-asparagine]-, [6-hemi-D-cystine-], [7-D-proline]-, and [8-D-leucine]-oxytocin, on reverse phase columns were investigated. The effects of solvent, pH, and salt concentration were studied. Using the solvent systems 10% tetrahydrofuran-ammonium acetate buffer or 18% acetonitrile-ammonium acetate buffer and the muBondapak C18 support, oxytocin was separated from each of its diastereoisomers under all conditions studied, but the order of elution of diastereoisomers was highly dependent on solvent and to a lesser extent on pH. Separations of the hormone and its diastereoisomers on reverse phase HPLC and on classical partition chromatography on Sephadex G-25 were compared. The results are discussed in terms of the interactions of the solute with the reverse phase column and the solvent system. Implications of these findings in terms of the different solution conformations of the peptides are discussed.
Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Ocitocina/isolamento & purificação , Sequência de Aminoácidos , Cromatografia em Gel , Concentração de Íons de Hidrogênio , Ocitocina/análise , Ocitocina/síntese química , Conformação Proteica , Sais , Solventes , EstereoisomerismoRESUMO
Using a simple injection adapter of our own design, the tetrahydrocannabinol content of marlhuana was determined by gas chromatography. The injection method obviates the need for preliminary extractions and allows analyses to be conducted on milligram quantities in less than thirty minutes.