THE FIRE DEBRIS SAMPLE WAS ONE OF SEVERAL RECEIVED AT THE LABORATORY IN CONNECTION WITH SUSPECTED ARSON. THE GAS CHROMATOGRAPHIC ANALYSES WERE CARRIED OUT USING A VARIAN 2700 GAS CHROMATOGRAPH EQUIPPED WITH FID AND A DUAL PEN RECORDER. TO MAKE A BETTER DECISION AS TO THE SIGNIFICANCE OF A PARTICULAR CHROMATOGRAM IN CASES WHICH ARE INDEFINITE, SOME PEAKS IN THE CHROMATOGRAM MUST BE IDENTIFIED. SINCE THE RESIDUAL VAPORS FOUND IN DEBRIS SAMPLES ARE OFTEN VERY LOW, ONLY GAS CHROMATOGRAPHY COMBINED WITH MASS SPECTROMETRY HAVE BEEN FOUND EFFECTIVE. USING BOTH METHODS, THE PRESENCE OF BENZENE, TOLUENE AND ETHYLBENZENE IN THE SAMPLE WAS CONFIRMED, AND A MOLECULAR WEIGHT OF 104 WAS OBTAINED AS BEING THE LARGE UNIDENTIFIED PEAK. IT WAS FOUND THAT THE AROMATICS FOUND IN THE DEBRIS SAMPLE WERE PROBABLY THE RESULT OF A POLYSTYRENE PLASTIC ITEM CONSUMED IN THE FIRE, AND NOT THE RESIDUE FROM AN ARSONIST'S FLAMMABLE LIQUID. THUS, THE WIDESPREAD USE OF POLYMERS COUPLED WITH THE EXTREME SENSITIVITY OF THE GAS CHROMATOGRAPHY SHOULD SERVE TO MAKE AN ANALYST CAUTIOUS WHEN AN UNFAMILIAR PATTERN WITH A FEW PEAKS HAVING RETENTION TIMES SIMILAR TO KNOWN FLAMMABLES IS OBTAINED FOR A DEBRIS SAMPLE. THE GAS CHROMATOLOGY/MASS SPECTROMETRY METHOD WITH ITS SENSITIVITY AND SPECIFICITY CAN BE USEFUL IN FURTHER ANALYZING SUSPECTED ARSON SAMPLES WHEN THE GAS CHROMATOGRAPH DOES NOT PROVIDE A DEFINITE ANSWER. TABULAR DATA AND REFERENCES ARE GIVEN. (MJW)