Supplies and Services for Mass Spectrometers, Gas Chromatographs
and Liquid Chromatographs
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7 | Last Update: 01/31/00 |
INTRODUCTION
Manufacturers are becoming increasingly concerned about the purity of their finished pharmaceutical preparations. Trace amounts of residual synthesis by-products, impurities in the synthesis chemicals, or decomposition of finished pharmaceutical product are often present in finished pharmaceutical preparations in levels down to parts per million (ppm) and a method is needed to detect and identify these impurities.
The technique of Direct Thermal Analysis utilizing the Short Path Thermal Desorption System permits the analysis of solid samples without the need for prior solvent extraction or other sample preparation. Using this technique, it is possible to analyze solid pharmaceutical samples to determine the solvent residues and impurities remaining after manufacture. Sample sizes ranging between 1 milligram and 250 milligrams of the pharmaceutical in question were inserted directly into the Glass Lined Stainless Steel (GLT) Thermal Desorption Tube. The new "Short Path Thermal Desorption System" was utilized to permit the direct sparging of the volatile and semi-volatile components from the solid pharmaceutical samples directly into the GC injection port with subsequent GC and MS analysis. Neither solvent extraction nor the use of vapor traps were required. This technique permits the maximum sensitivity of analysis due to this direct injection technique.
The Scientific Instrument Services' "Short Path Thermal Desorption System" was attached to the injection port of a Hewlett-Packard 5971 GC/MSD. A J&W DB-5, 25 m x .25 mm, 0.25 u film thickness capillary column was used for this study. The GC was used in the splitless mode at the flow rate of 0.5 ml/min.
