Spent cartridges found at a crime scene may provide information for determining the approximate time that a firearm was discharged. The solid phase microextraction (SPME) technique has been used to detect volatile compounds from firearms and spent cartridges. In this study, the volatile compound, naphthalene, was monitored because of the reproducibility and detection limit of the peaks produced with GC-MS. The concentration of the naphthalene remained constant prior to laboratory analysis. The naphthalene peak height produced a curve-fitting line that was used to estimate time since discharge. The SPME technique combined with GC-MS was used to detect several volatile combustion compounds in shotgun shells after they had been fired. The volatile compound naphthalene proved to be a suitable peak to monitor because of its reproducibility and noticeable decrease in concentration over time. The decrease in concentration of the naphthalene could be used to estimate time since discharge. A glass vial system was found to have the ideal conditions to preserve the condition of a spent cartridge in that the concentration of the naphthalene did not significantly decrease prior to laboratory analysis. Repeated SPME sampling could be performed on the shell without a significant decrease in the naphthalene concentration. The vial system also included other evidence valuable to a forensic crime lab. A shotgun shell as a piece of evidence needs to be placed in a sealed container. The vial provides this condition and also allows testing without disturbing the shell. Future work will involve examining this system with other types of ammunition cartridges, and examination of other types of SPME fibers that may be more suitable for monitoring volatile compounds. 5 figures, 5 references