Automated identification by computer of the mass spectra of drugs in urine or serum extracts.

Gas chromatography/mass spectrometry (GC/MS) is the method of choice for confirming the presence of drugs tentatively identified in urine or serum by thin-layer chromatography, gas chromatography, or immunoassay. One of the most widely used GC/MS systems is the Hewlett-Packard (HP) Model 5970 mass selective detector equipped with a work station programmed in Pascal. Searching of mass spectra after a GC/MS run must be done manually, and this can take hours, especially when there are many peaks in a chromatogram to check. I have developed software that allows the unattended searching of all peaks in a run, using a forward search algorithm with a custom-made drug library developed over a period of 5 years, and a reverse search with a 1600+ drug library from HP or another in-house drug library. Using these libraries with the two algorithms maximizes the chances of finding a drug peak and identifying it correctly. Individual searches take about 5 seconds each. Overall search time of nearly 200 mass spectra per run takes about 40 minutes, including printing time. This software has proven to be both labor saving and effective in positively identifying drugs.