No abstract

Summary

The enantiomers of both terbutaline and ephedrine were separated by capillary electrophoresis using electrolyte solutions of heptakis(2,6-di-O-methyl)-beta-cyclodextrin in low pH buffers. The analytes were detected by ion spray mass spectrometry using selected ion monitoring or by selected reaction monitoring in the positive ion mode. Both the free drug enantiomers and the noncovalent enantiomer-cyclodextrin inclusion complexes for terbutaline can be detected simultaneously using this method. The feasibility of using CE/MS for chiral purity determination is demonstrated. In addition, a comparison of UV detection versus mass spectrometry detection for a spiked urine sample is included to demonstrate the selectivity and sensitivity advantages of the mass spectrometer as a CE detector.

An on-line immunoaffinity extraction-coupled column capillary liquid chromatography/tandem mass spectrometry (IAE/LC/LC/MS/MS) method is described. The system involves three columns, a 2.1-mm-i.d. protein G immunoaffinity column with noncovalently immobilized antibody specific to the analytes of interest, a packed capillary trapping column, and a packed capillary analytical column. With use of a short packed capillary trapping column, the protein G column could be operated at flow rates of 2.5-4 mL/min while the packed capillary analytical column was maintained at a flow rate of 3.5 microL/min. Human urine diluted 1:1 with phosphate-buffered saline was pumped directly onto the immunoaffinity column without pretreatment and was analyzed by electrospray mass spectrometry following the column switching process. Sample handling and transfer procedures were eliminated. The system was optimized and evaluated for the determination of LSD, its analogs, and metabolites in spiked human urine at low part-per-trillion (ppt) levels using mass spectrometric detection. LSD-positive human urine specimens from LSD users were also analyzed. Concentrations as low as 2.5 ppt of LSD and several of its analogs were detected in spiked human urine using IAE/LC/LC/MS/MS/. This is 20-fold below our previous limit of detection using solid phase extraction and LC/MS/MS.

The quantitative determination of some isoquinoline alkaloid natural products is described using combined capillary electrophoresis-ion trap mass spectrometry (CE/MS). The benchtop ion trap is a previously described modified commercial Varian Saturn II system equipped with an in-house constructed atmospheric pressure ionzation (API) ion source which was operated in the ion spray CE/MS mode. All relevant operational parameters have been optimized for the CE/MS experiments described in this work. A coaxial sheath flow of solvent buffer was used to facilitate ion spray CE/MS operation. Analysis of synthetic mixtures containing nine related isoquinoline alkaloids provided full-scan mass spectra for these compounds with injected quantities as low as 370 attomole. The signal-to-noise ratio was better than 10/1 for theextracted ion current electropherograms of the parent ions for these compounds with injected quantities in the 370-510 attomole range. CE/MS analysis of methanol extracts from the natural bark of Pbellodendron wilsonii&s well as an herbal medication provided full-scan mass spectra for the identification of major and minor components in the mixture. Quantitative analyses were carried out using tetrahydroberberine as an internal standard. The standard curve ranged from injected levels of 0.6 to 16 pg (1.7 to 45 fmol) and had correlation coefficients of 0.998 and 0.999 for berberine and palmatine, respectively. These results suggest that the ion trap CE/MS system is sufficiently sensitive and reliable to provide acceptable quantitative analysis of synthetic and natural product mixtures.High-performance capillary electrophoresis (HPCE) is recognized as a powerful technique for the separation and analysis of samples composed of charged species which range from small ions to large proteins.1-3 The coupling of capillary electrophoresis with mass spectrometry (CE/MS) offers added capability by providing important information necessary for the identification and confirmation of components in complex mixtures. On-line CE/MS was first reported by Smith et al.4 and later by Lee et al.5 where capillary electrophoresis was coupled to a quadrupole mass spectrometer using an atmospheric pressure ionization electrospray and an ion spray interface, respectively. Since then, other types of mass