Estimation of cartridge discharge time is very important for the investigation of same gun-firing related cases. Accompanied with shooting, nitrate gunpowder in cartridges burns and reacts vigorously, while a large series of gaseous and solid reaction compounds are generated and absorbed onto the internal surface of cartridge cases. Experiments were conducted in order to detect the volatile nitrate organic gunshot residues (OGRS) of China-made 7.62 mm type 64 and 9 mm type 92 pistol cartridge cases. After discharged, these two cartridge cases were sampled using solid phase micro-extraction (SPME), and analyzed by gas chromatographic-thermal energy analyzer (GC-TEA).One double peak can be observed in all GC-TEA chromatogram as late as 10 days past discharge. The double peak became weaker along with the time elapsing since discharge. From the discharge time of Day 1 to Day 7, a notable peak was identified in GC-TEA chromatogram of the two cartridge cases in the test time segment from 1 to 2 min. On Day 1, it was merged by one sub-peak of weaker and sharper plus another sub-one of stronger and broader, continuing to be only a peak notably wider, becoming much weaker on Day 9, and eventually hardly seen on Day 11 after discharge. For the first time, the variety curves of the volatile nitrate organic compound content of China-made 7.62 mm type 64 and 9 mm type 92 pistol cartridge cases were developed, and the time since discharge of these two cartridge cases can be estimated.%现代枪弹的发射常伴随着含氮发射药燃烧产生多种气相和固相射击残留物的过程，射击后可挥发的射击残留物附着于弹壳表面，并随时间不断从弹壳内表面逸散。这种逸散过程的量度是估计发射时间的重--素。采用固相微萃取方法对国产64式7.62 mm 手枪弹和92式9 mm 手枪弹进行分析提取，使用气相色谱-热能分析仪分析提取的挥发性含氮有机物。测量含氮有机物相对含量随时间的推移变化，并使用这一含量参数变化估测射击时间。在64式手枪弹和92式手枪弹弹壳中均检测到随时间推移而减少的含氮有机物，这类物质在射击完成后的10天左右仍能检出。从1天和7天的谱图中，能在1~2 min 的时间段内观察到一个显著的峰值，这一峰值在1天的谱图中表现为一个较弱的尖锐峰和一个较宽的峰形合并而成，在随后的谱图中只能看见一个显著的宽峰；在同比例坐标下，这一峰值在9天的谱图中变得较为微弱，在11天的谱图中已经难以被观察到。本研究首次采用气相色谱-热能分析法获取了国产64式与92式手枪弹射击弹壳内含氮有机物量随射击时间的变化曲线，可由此推算估计这两类手枪弹的射击时间。
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