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Solution conformations of the polypeptides beta endorphin (beta-END) and a cysteine peptide (CYSP) were investigated with the use of particle beam LC/FT-IR spectrometry. Gradient elution HPLC with mobile phases that contained acetonitrile with 0.1% TFA (v/v) and 0.1% aqueous TFA (v/v) were used. The conformations of both polypeptides were studied in 0.9% sodium chloride injection USP, 5% dextrose in water injection USP and sterile water for injection USP. Additional conformational studies over a pH range of 2-10, temperatures of 25, 50, 75 and 100 degrees C and after storage for 24 h were investigated. The studies indicated that the two polypeptides did not behave similarly under identical conditions. It was observed that both beta-END and CYSP had slightly different conformations in the various parenteral solutions. It was also shown that the conformation of CYSP changed with both pH and temperature while beta-END was conformationally stable to both temperature and pH. The identity of the peptides and the conformationally sensitive charge-state intensities of the peptides were investigated with electrospray ionization mass spectrometry (ESI/MS). The combination of IR and MS data allowed an estimation of solution effects on the conformations of the model polypeptides.

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High performance liquid chromatography procedures have been developed for the assay of propofol-thiopental sodium and propofol-ondansetron mixtures. The separation and quantitation of propofol-thiopental sodium were performed on a stable bond phenyl column at ambient temperature using a mobile phase of 55:45 v/v aqueous 0.01 M monobasic postassium phosphate pH 4 -acetonitrile at a flow rate of 1 mL/min, with detection set at 235 nm. The separation was achieved within 20 min. Propofol and thiopental sodium were linear in the 12.7 -38 and 31.4 -94 pg/mL ranges, respectively. Accuracy and precision were in the range 0.2 -2.6 and 0.2 -3.2%, respectively, for the two analytes and the limits of detection for propofol and thiopental sodium were 1210 and 317 ng/mL, respectively, based on a signal to noise ratio of 2 and a 20 pL injection. The separation and quantitation of the propofol-ondansetron mixture was achieved on a 10 vm particle size phenyl column.,using a mobile phase of 50:50 v/v aqueous 0.01 M monobasic potassium phosphate pH 4 -acetonitrile at a flow rate of 1 mL/min, with detection set at 268 nm. The separation was achieved within 15 min. Propofol and 2285 Copyright 0 1996 by Marcel Dekker. Inc Downloaded by [UQ Library] at 05:31 04 November 2014 2286 KING ET AL.ondansetron were linear in the 2.5 -37.5 and 0.48 -7.2 pg/mL ranges, respectively. Accuracy and precision were in the range 0.4 -2,4 and 0.2 -0.6%, respectively, for the two analytes and the limits of detection for propofol and ondansetron were 1 17 and 6 1 ng/mL, respectively, based on a signal to noise ratio of 2 and a 20 pL injection.