Abstract: In order to improve the detection rate of fire evidence, the preservation of the original gasoline in the soil samples of the fire scene under the influence of microbial degradation effects by freezing treatment and triclosan solvent immersion were researched, and comparison of the inhibitory ability of solvent and freeze inhibition on microbial degradation were carried out. The analysis of samples by GC- MS was carried out and the Pearson correlation coefficient was used to analyze the correlation between the preserved sample and the original gasoline, and the detectioneffect of the gasoline characteristic components in the sample was
studied. The results showed that the sample after freezing treatment is related to the polarity of the original gasoline, and the detection of the characteristic components is better. The research results can be applied to the identification of daily fire investigation work.

Key words: fire investigation, gasoline, freezing, Pearson correlation coefficient