Instrumental Data for Drug Analysis, Second Edition by Terry Mills

Author:Terry Mills
Language: eng
Format: epub
Publisher: Taylor & Francis (CAM)

MASS SPECTROMETRY

The mass spectra were acquired on a Hewlett-Packard 5985B GC/MS operating in the electron impact (El) mode with an electron energy of 70 ev. Unless otherwise noted, the samples were introduced via a 5 % phenylmethyl silicone column into the ms source, which was maintained at 200°C.

Every effort was made to standardize the sample size and mass spectrometer tuning to ensure consistent spectra throughout this collection. Where it was necessary to manipulate the spectra, e.g., to remove traces of the injection solvent or column background, due care was exercised to avoid distorting the data. Mass calibration was checked several times a day, and the inertness of the interface was demonstrated daily by the analysis of cholesterol, which produced a 386/368 ion ratio of greater than 2:1.

In a few cases, the only appropriate means of introducing a sample was by direct insertion probe, also called solid probe or DIP. These spectra are identified where they occur in the book.

Finally, the mass spectra were plotted on a HP 7550A graphics plotter using a routine written especially for this work. Although prominent ions in each spectrum are labeled, the user should be aware that these masses were selected on the basis of abundance and may not indicate the most significant fragments for each compound.

A cumulative index of the mass spectra, sorted by base peak, is included as Appendix E.

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