INFLUENCE OF THE INJECTION TECHNIQUE ON THE THERMAL-DEGRADATION OF COCAINE AND ITS METABOLITES IN GAS-CHROMATOGRAPHY

Thermal degradation of some substances due to high temperature at the injection port and/or the type of injection technique used may limit the usefulness of gas chromatography with conventional detectors or coupled to mass spectrometry. To minimize thermal degradation of cocaine and its metabolites, chromatography was performed using two different insert liners and a cool on-column inlet. When using a packed liner, marked degradation of all compounds was observed. The degradation process was reduced by the use of an open liner and, when the cool on-column inlet was employed, essentially no degradation occurred.