Positive secondary-ion mass spectra and thin-layer chromatography/mass spectrometry of phenothiazine drugs

High-performance liquid chromatographic assay of (+/-)-ethopropazine and its enantiomers in rat plasma

Two high-performance liquid chromatographic (HPLC) methods are described for determination of (+/-)-ethopropazine (ET) in rat plasma. After deproteination and liquid-liquid extraction, assay of (+/-)-ET was performed using either a C18 column (non-stereospecific assay) or an (alpha-R-naphthyl)ethylurea column (stereospecific assay). The UV detection was at 250 nm. Mean recovery was >85%. Both assays demonstrated excellent linear relationships between peak height ratios and plasma concentrations; quantitation limits were < or =25 ng/ml, based on 100 microl rat plasma. Accuracy and precision were <17% with both methods. Both methods were applied successfully to the measurement of ET plasma concentrations in rats given the drug intravenously.

High-performance thin-layer chromatography/fast atom bombardment (tandem) mass spectrometry of Pseudomonas rhamnolipids

Several rhamnolipid preparations from Pseudomonas strains were studied by thin-layer chromatography/fast atom bombardment (TLC/FAB) mass spectrometry and TLC/FAB tandem mass spectrometry (MS/MS). The preparations were separated with normal-phase (Silica 60) and reversed-phase (RP-8) chromatography. Silica 60 plates appeared to be very useful in the separation of rhamnolipids according to the number of monosaccharide residues present. Spectra which show characteristic fragment ions could be obtained from components of mixtures with a total sample size of less than 200 ng. Chromatography on RP-8 plates gave a good separation of the rhamnolipids based on the length of the fatty acid alkyl chain. MS/MS of the sodium cationized molecules gave information about the sequence of the building blocks. Particularly, heterogeneity in beta-hydroxy fatty acid composition was determined for the principal as well as minor components present in natural rhamnolipid mixtures.

Progress in densitometry for quantitation in planar chromatography

The principal methods for obtaining quantitative information from separations performed by planar chromatographic techniques are reviewed. Recent advances in obtaining structural information for sample identification of separated components are also discussed. Reasonable expectations concerning future developments in densitometry are made.

Imaging analysis and selected sequence monitoring of small peptides using planar chromatography/secondary ion mass spectrometry

Mixtures of enkephalins and bradykinins contained on silica gel thin-layer chromatograms were imaged by secondary ion mass spectrometry. Spatial profiles of the sample distribution in the chromatographic plane were determined using a precision manipulator that moves the sample into and out of the primary beam generated in a liquid metal gallium source. For instance, spatial profiles are conveniently measured by monitoring the protonated molecule [M + H]+ of each compound or, in a selected-sequence monitoring experiment, by monitoring a sequence ion common to the members of each peptide group. The latter experiment is useful for quick location and identification of a class of peptides separated by planar chromatography, including thin-layer chromatography and electrophoresis.