Rapid ESI-MS method for examining the thermal decomposition of pharmaceuticals

A Finnigan MAT TSQ 700 triple quadrupole mass spectrometer equipped with a Harvard 22 syringe pump has been used to investigate the thermal decomposition of three common pharmaceuticals, acetaminophen, indomethacin, and mefenamic acid. In addition, comparative measurements on these same drugs were carried out by HPLC after thermally degrading them at elevated temperatures in order to evaluate the usefulness of the ESI-MS as a rapid means of determining the relative stability and identifying thermal decomposition products. Similar results were obtained between the two techniques (i.e., the relative rates of decomposition were mefenamic acid > indomethacin > acetaminophen), with the advantage that the ESI-MS approach was much quicker to perform. (C) 2004 Wiley-Liss, Inc. and the American Pharmacists Association.