The trace analysis of biological fluids or tissues for toxicologically active compounds has traditionally been frustrated by a combination of very complex, dirty samples and relatively non-selective detection methods. The use of capillary GC columns together with highly selective detectors, such as the mass spectrometer (MS), has provided us with very sensitive and specific methods of trace organic analysis. Gas chromatography-microwave induced plasma (GC-MIP) emission spectroscopy has long been used for the trace analysis of both nonmetals and metal derivatives. Unfortunately, GC-MIP methods have rarely been applied to the trace analysis of compounds derived from biological matrices, despite the obvious fact that it should provide significant opportunities and advantages when compared with almost all other conventional, inexpensive GC detectors (FID, ECD, PID, AFID, etc.). We have now developed and applied GC-MIP based trace analytical methods, in combination with n-butyl boronate ester derivatization, for catechol, 3-methylcatechol, and 4-methylcatechol, two of which are present in a number of human urine extracts. We describe the final GC-MIP conditions for the analysis of standards and real samples, as well as a comparison of the qualitative and quantitative results vs trimethylsilylation and GC-FID analyses of these same samples.